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The 51.6% solution

This is just a quick note on a technical problem that plagues digital Leica cameras when used with older Nikkors: back focus. It is gratifying to know that Leica has finally recognized that many of its lenses don’t work so well on digital Ms due to “focus errors” that allegedly compound over the years. The real reason is probably more that film planes are actually and unintentionally curved, and a lens that makes the grade at the center there back-focuses elsewhere.

I was struggling a bit with a 10.5cm f/2.5 Nikkor, which though absolutely lovely aesthetically is one of the worst-engineered Leica lenses ever from a mechanical standpoint. And it back-focused. It back focused more with some Leica M adapters than others, but still.

Strike one with this lens is that the aperture unit rotates along with the entire optical unit. This means that if you adjust the collimation washer (for reasons I don’t fully understand, it’s always 0.05mm needed with any lens – just about the same thickness as Scotch tape), you also then have to reset the aperture ring to read properly. Also not 100% sure that infinity optical focus was really the problem.

Strike two is that the amount of front cell movement needed to compensate for back focus is absurdly great. So here, you’re messing around with focal length, but this the same way the MS-Optical Sonnetar gets calibrated…

Strike 3 is that the RF cam is not adjustable at all, with the tab pushed by a plunger running on a wheel that fits in a spiral track in the helicoid. Guess how this tab was adjusted for infinity at the factory? With a file. It makes sense, in a way. Calibrate the fixed infinity point on the focal plane by shimming the optical unit, calibrate focus at infinity by grinding the RF tab, and fix close focus by shimming the front cell. But it utterly sucks when you find out, 60 years later, that the tolerances that looked good on film with a Leica IIIc look like holy hell on digital.

So when you are dealing with focus errors, you have to imagine that the standard is a 51.6mm lens. At that focal length, if the RF matches the film-plane focus, the focus will always be correct, even if the infinity stop of the lens is beyond “infinity” on the scale.

For a telephoto lens, the rear cam still pretends it moves like a 51.6mm lens, but the actual optical unit moves much further. Hence, in a lot of cases, you can simply use a thinner LTM adapter (I think I’ve written about this before… somewhere). Most cheapo ones are thinner than the 1.0mm they are supposed to be.

But there is a different way to hack this with the 135mm, 105mm, and 85mm Nikkors: simply apply a thin and even coat of clear nail polish to the RF tab on the lens. This is a trick that you could theoretically do with lenses that have a rotating RF coupling ring (not tab), but it works exceptionally well with the Nikkors because the camera’s RF roller simply rests on the tab and doesn’t roll along it. This means that you only need to get the coating thickness right over a very short distance. Materials needed:

  • Sally Hansen clear top coat (not “nail nourishing,” just the hard kind).
  • CVS Beauty360 brand Nail Polish Corrector Pen (essentially a marker full of acetone that you can use to thin or remove extra nail polish).
  • LensAlign focusing target (if you own a Leica, you really want one of these anyway, just to figure out what the devil all your lenses are doing as you stop down).
  • Reading glasses.

So basically all you need to do is put a very thin coat of polish on the polished surface of the tab. Let it dry for 20 minutes. Here is the goal:

  • At f/2.5, your focus should be such that the 0 point is barely focused, with most of the DOF in front.
  • At f/2.8, your focus should be dead-centered around 0. The lens is actually way sharper here than at f/2.5. Doesn’t seem like much of an aperture change, but it is.
  • At f/4, your focus will be such that 0 will barely be in focus, with most of the DOF to the rear.
  • From f/5.6 down, the DOF will grow so that 0 is always in focus.

If it works, you’re done. The focusing errors this might induce further out are subsumed by depth of field increasing. If you need another coat, add one. If you are now front-focusing too much, use the Corrector Pen to remove some of the extra (or use a very fine nail buffer to remove some).

Never file or try to grind down the tab if your lens is front-focusing. Unless you can do it totally square, your lens will behave differently on different cameras. Leave this situation to a pro.

Leica Monochrom Typ 246 x PC-Nikkor 28mm f/3.5

People understand why tilt lenses exist – making super-expensive Canon DSLRs produce pictures that look like they were taken with a toy camera (or making the subjects themselves look like toys). No one knows, though, why shift lenses were once a thing. It’s all a matter of perspective.

The truth, from a certain point of view

Photography always has (and always will) present this problem: needing to fit a large object into a frame that is constrained by lens focal length. Conceivably, with a superwide lens you could, but then you end up with a lot of extra dead space in the frame. Which defeats the purpose of using large film or sensors.

Solution?

If you want to get the whole thing in frame with the minimum number of steps or expenditure of time and money, your choices are to use a really wide-angle lens, tilt a camera with a more moderate wide-angle up, learn to fly. All of these  are sub-optimal. First, the really wide-angle lens is great in that you can capture the top of the object without tilting the camera. The problem is that making an engaging photo with a wideangle is actually extremely difficult – because it tends to shrink everything. Depending on how the sun is, it also stands a better chance of capturing the photographer’s shadow. Second, tilting up a camera with a more moderate wide-angle lens “up” turns rectangular buildings into trapezoids, which works for some pictures but definitely not others. Finally, learning to fly is difficult. But watch enough Pink Floyd concert films, toke up with the ghost of Tom Petty, or study Keith Moon’s hotel swims, and you might.

Do you skew too?

Assuming you are reasonably competent, you can correct perspective using software, by skewing the canvas. This is a take on the old practice of tilting the paper easel with an enlarger. This was a limited-use technique, generally practiced by people who could not use view cameras and tripods but still had to come up with a presentable representation of a tall object.  There were (and substantially still are) three issues here: crop, depth of focus, and dis-proportion. First, the crop came from the fact that tilting an easel meant that the projected image was trapezoidal and not rectangular, meaning that from the get-go, it had to be enlarged until the paper was filed. This still happens with digital. Second, the depth of focus issue is related to the fact that enlarging lenses are designed to project to a surface that is a uniform distance from the enlarger (i.e., projecting one flat field onto another). You would have to stop down the lens severely, or use a bigger focal length, which in turn required a taller enlarger column to maintain the same magnification.

The digitization of perspective correction uses computation to project the flat image onto a skewed plane, using interpolation and unsharp masking. This solves the apparent sharpness issue, but it degrades quality. Finally, dis-proportion comes from the fact that straightening converging verticals starts from a place where certain details are already compressed via the original perspective. For example, looking up at a tall building from a short distance, the windows look shorter (top to bottom) than they would if you were looking straight at the window from its own level.

So even when you manage to re-skew the canvas/field/whatever, you now have an image that is too “fat.” On enlarging paper, you would be forced to make a cylindrical correction to the negative (which is not practical in real life). On digital, there are specific transformations that you can perform to correct (for example, the adjustable ratios on DxO Perspective and Lightroom.

So skewing is a useful technique, but it’s still better to skew less.

Shifting your thinking: the mirror years

View cameras have used the concept of shift and tilt to adjust for situations where the viewpoint was wrong (shift) or depth of field was insufficient (tilt). Raising the front standard of a bellows-type plate camera was always standard practice to improve photographs of tall objects, especially in an era where wideangle lenses were not super-wide by today’s standards. Lens board movements were easy to achieve because there was always some distance between the lens mount and film plane in which to insert a mechanism to raise the lens relative to the film. And because there is no control linkage between the lens/shutter and the rest of the camera, you’re not losing automation. You never had any!

But these cameras were not small. The smallest bellows-type camera with lens movement features was the Graflex Century Graphic, a delightful 6×9 press-style camera. On many bellows-type cameras, though, there was no real provision for using a shifting viewfinder. The press-style cameras had wire-frame finders that provided a rough guide, but nothing could tell you whether the lens was actually level outside a gridded ground glass. Later in the game, the Silvestri H would present as the first camera with automatic finder shift, as well as a visible bubble level. Linhof used a permanently-shifted lens assembly (and viewfinder) on the Technorama PC series, and Horseman provided shifted viewfinder masks for the SW612P, though these were available only as “all the way up/down” or “all the way left/right.”

The shift mechanism, though, could not be adapted to SLRs easily due to three constraints:

  • Most SLRs lenses are retrofocal – meaning that the nodal point of the lens is more than the stated focal length from the imaging plane. It takes a ton of retrofocus to insert a shift mechanism into an interchangeable lens that has to focus past a mirror box. More retrofocus means bigger lenses So when perspective control lenses began to appear for SLRs (35mm and 6×6), they were huge. Maybe not huge by today’s standards, but a 72mm filter size is pretty big for a Nikon SLR whose normal filter size is 52mm.
  • To achieve an image circle large enough to allow shift around what is normally a 24x36mm image circle, it is necessary to use a wide field lens and stop it down severely (illumination with almost any lens becomes more uniform as it is stopped down).
  • Most cameras can only meter PC lenses correctly in their center position, wide-open. Where shift mechanisms eliminate direct aperture linkages to the camera, you’re back to the 1950s in metering and focusing – then shifting – then manually stopping down to shoot (now corrected by the use of electronic aperture units in $2K plus modern Nikon and Canon PC lenses).

Viewing is not a lot of fun with 35mm SLRs; when stopped down, PC lenses black out focusing aids (like split prisms and microprisms) and still require careful framing to keep parallel lines parallel. So you need a bright screen – plus a grid or electronic level. Suffice it to say, a lot of people regard perspective control to be a deliberative, on-tripod exercise when it comes to SLRs and DSLRs. Maybe it’s not.

A new perspective: full frame mirrorless?

So here come mirrorless cameras (well, they came a while ago). Now you can fit any lens ever made to any mirrorless body. The optical results may vary, but at least physically, they fit.

— Getting the lens in place

So I grabbed the nearest available PC lens I could find, which was a 28/3.5 PC-Nikkor. Not AI, not even from this century. Released in 1980, it is a beast. I plugged this into a Konica AR body to Nikon lens adapter, and from there into a Imagist Konica lens to Leica body adapter. Why all these kludgy adapters? The answer is actually pretty simple: the Imagist has the correct tolerance to make infinity infinity, and the Konica adapter does the same. This is not a small consideration where you might be zone focusing a lens.

Then I plugged this kludgefest into a Leica M typ 246 (the Monochrom). Because why not start with the OG of mirrorless camera platforms? Of course, you can’t use a rangefinder with a Nikon SLR lens, so I plugged in an Olympus EVF-2 (which is the ‘generic’ version of the Leica EVF-2.

— Getting it to work

The Nikkor has two aperture rings. One is the preset, where you set your target aperture. The other is the open/close ring, which goes from wide-open to where the preset ring is set.

I turned on focus peaking and set the preset for f/22 and the open/close for f/3.5. I was able to establish that infinity was correct.

Next, I stopped down the lens (both rings to f/22), expecting that just as on an SLR, the EVF would black out. Worked perfectly.

I hit the “info” button to get the digital level, and it was off to the races. The lens has a rotation and a shift.

— But how well does it actually work?

The functionality is actually surprisingly good. On a Leica, it’s just stick the camera in A, stop the lens down to f/16 and 22, and point and shoot.

The digital level obviates the use of a tripod or a grid focusing screen, and you really just frame, turn the shift knob until the perspective looks right, and there you go. There are a couple of limits

You can’t use maximum shift along the long side of the film, but the only penalty is a little bit of a tiny shadow in the corner. And that’s with a full-thickness 72mm B+W contrast filter. You get 11mm shift up and down (i.e., along the short dimension of the firm) and 8mm left and right (nominally; as I stated, you can get away with more under some circumstances).

Aside from that, there are some minor annoyances like making sure you haven’t knocked the aperture ring off the shooting aperture. Or knocking the focus out of position (it’s a very short throw…).

BUT THE DUST! And here is the rub – shooting at f/16 and f/22 brings out every dust spot on your lens. Normally, you would shoot a Leica M at f/5.6, f/8 max. But PC lenses – like their medium and large format cousins – are designed to max out their frame coverage at very small openings. So I had never cleaned the sensor on my M246 in four years, and I got to spend an evening working on a hateful task that included swabs and ethanol and bulbs and the Ricoh orange lollipop sensor cleaner.

— And how sharp?

Very. Diffraction is supposed to start becoming visible at f/11 on this combination at 1:1, with it showing up in prints at f/22.

Pictures stand up to the old 1:1 test, except in the corners where you have over-shifted along the long side. Recall that in lot of situations, two of the last bits of corner are usually sky, where a tiny amount of blur is not going to be of any moment.

How well this will work on a color-capable camera is a question, especially since lateral color would come out. But right now, this is posing the most acute threat to 6×4.5 cameras loaded with TMY.

Konica Hexar (AF)

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This is the text of the page that had its debut in 2001 and (for better or worse) helped trigger Hexar-mania. Last update was late February 2018.

Overview: (Scratching off where there was grime)..”H-E-X-A-R.” Captain, HXR is a Canonet that was sent out of our solar system in the late 1960s. It encountered a machine planet where the computers examined it, understood its mission, and elaborated on its mechanics. It grew, and it evolved… and gained consciousness.

Generalities: Autofocus camera with high-speed 35mm f/2 lens and leaf shutter. Form factor is similar to a Leica M.

History: the Hexar came about in 1992, reportedly a last vanity project for the Konica engineers who worked on the FT-1. Or so the story goes. Some of the key technologies on the Hexar, such as a sealed lens barrel, projected brightline finder (zoom on some models, albeit always with fixed framelines), and tri-window AF showed up first on the 1988 models MR640 (weather resistant) and shock-resistant Genba Kantoku (“Site Supervisor”), a ruggedized camera designed for construction sites. In fact, the wind motor of the Genba K. sounds like the Hexar in “loud” mode.

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Do you also see a resemblance to the Fuji GA645 with the autofocusing side-pod module?

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Tokina’s site, oddly, was the only one that had a picture of a clean GK. Most examples of this camera, including mine, look like holy hell. This is the fixed 40mm version, which has a shallower silver protrusion.

Before you confuse the Genba K. with a poor man’s Hexar, understand that the lens and operation are totally different; the Genba Kantoku has a 40/3.5 (3 elements, 3 groups) or 40/3.5-60/5.2 bifocal lens (3/3 and 6/6) of completely different construction. And on the Genba Kantoku, here are your controls. All of them: flash on. Flash off. Self-timer. Manual rewind. No nonsense here.

Later models of the Genba Kantoku (the 28mm and 35mm second-generation models in 1994) apparently acquired the Hexar’s funky electronic shutter and accordingly had maximum shutter speeds of 1/280 sec.

Construction. The construction is all metal, with the exception of the top and bottom covers, which are a period-typical black chrome (or bright chrome) plated on polycarbonate. Which is a good thing because if they were brass covers, this would be a very heavy camera. Konica made a big deal about the front barrel being a heavy alloy casting to add the retention of precision in focusing.

Lens. The lens is the Hexar’s raîson d’etre. In fact, it is legendary.

The 35mm f/2 Hexar (actually, Hexanon) lens has the imaging qualities of the 35/2 Leica Summicon-M and the general design of the Nikon 3.5cm f/1.8 W-Nikkor (the rangefinder lens from the 1950s and 60s – you know, the one whose Leica screwmount version sells for $1,800 and up today). Konica won’t go further than to call the design “Gaussian,” but Nikon has acknowledged on its 1001 Nights Site that this is a Nikkor derivative. Konica’s own technical materials reflect this design intent, although they also mention a slight recomputation aimed at allowing an electronically controlled aperture and shutter to be inserted between the lens groups. The aperture has 6 blades that form a perfect circle down to f/5.6, after which point, aperture shape is not that important.

This lens has been revised slightly and rereleased as the 35/2L Hexanon (chrome) and its optical twin, the 35/2 UC Hexanon (black paint), both in Leica mount. These are beautiful lenses run in limited numbers (1,000 and 2,000 respectively).

The lens out of the original Hexar AF has been independently converted by many into a Leica M lens (though this takes a lot of work and frankly is not as elegant as Konica’s own ported versions). But it is a lot cheaper way to do it.

hexar-lens.jpeg

This camera featured in a Konica white paper that discussed the camera’s total control of chromatic aberration. It also posts some impressive MTF compared to the lenses whose formula and optics it replicates. Wide-open, it exhibits a very smooth falloff from the center; at f/5.6 it is uniformly great.

hexar-mtf

Viewfinder: The viewfinder is a 0.7x window, with crosshair reticle for 2-channel infrared autofocusing, green light for focus confirmation, focused-distance indicator, shrinking-field, parallax-corrected projected framelines, and +/- indicators for over/underexposure. The front and back covers are glass, which is good for durability.

Rangefinder and limitations:  It is probably not a stretch to say that this camera has the most sophisticated active autofocusing system ever put in a camera.  The heart of the system is a unique 2-channel infrared rangefinding system that gauges distance in 290 steps out to about 10m.  It uses a central emitter and two receptors to help eliminate errors caused by parallax or subject reflectivity.  If the camera fails to see a return IR beam, it focuses to 20m, which is the hyperfocal distance of its 35mm f/2 lens.

3-point AF.jpeg

That is already insanely good, but the camera then applies an aperture-specific focus correction to account for focus shift (also described in a Konica white paper). The Hexar’s lens is optimized for wide-open operation; its spherical aberration causes the focus point to shift as the apertures get smaller.  The Hexar calculates this error and corrects as its goes.  Too bad AF SLRs don’t have this feature.

But wait.  This camera also can automatically compensate for 750nm or 850nm infrared film, too.  No IR marks, no guesswork.

And for the free set of steak knives, the camera’s AF system is temperature-calibrated as well.

If you need true infinity focus, you hit the MF button once. If you hold it down, you can set your distance manually (and the camera remembers every time you come back – useful for hyperfocal technique).

Nice design features: Programming, programming, programming. This camera is built around a first-rate lens and two key concepts. One is hyperfocal focusing. The other is perfect balancing of flash using a combination of techniques, including traditional distance-aperture programming, rear-curtain synch, and stopping-down mid-exposure. It is important to note that the Hexar cannot use high-voltage flash units like the early Vivitar 283. Only modern, low-synch-voltage units should be used to avoid frying the internal circuitry.

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The black model features a silent drive that slows focusing and advance to the point of being absolutely silent. Even in that mode, it still focuses and advances faster than you can. In fact, this camera can focus, compute exposure, and control flash in complete darkness. Instantly. You can add silent mode and a number of other advanced features to the Hexar Silver, etc. through a control sequence that you can find on the ‘net.

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Odd design limitations: 1/250 second top speed. Not that odd, really, if you consider the clear aperture those shutter blades have to cross and the fact that electronically-controlled shutters have different design limitations. Did you really think your Canonet QL17 shoots 1/500 at a true 1/500? Didn’t think so. Some people complain that you can’t use 800 ASA film with this camera outside. That misses the point, which is that you use lower-speed film to take advantage of the lens’s resolving power. Even 400-speed film is pefectly adequate, as in the big picture below (Kodak Supra 400). There is no cable or remote release, but I am not sure if this is a problem in a camera without a mirror to cause vibration. It does have a self-timer.

  • For the complainers about the top shutter speed, the workarounds should be fairly obvious: for outside shots (or inside with flash) get an ND8 filter, which takes a 3200-speed film down to 400. You will have to make sure that you change the ISO setting.
  • Another way is to just change films mid-roll, which is easy on this camera. When the camera reaches the end of the roll (which takes a lot longer than you think), it rewinds the film. Or you can use a ballpoint to press the manual rewind button. When the leader is about to be sucked into the canister, the camera pauses for 3 seconds, displaying [–]. This is your cue to open the back and take the leader-out cartridge. Otherwise, it finishes rewinding and displays [0]. The film advance is precise enough that the camera can be shot with one roll of film, rewound, loaded with another type, switched back to the first, and advanced (lens cap on) to the same spot on the first film (hence the leader-out). Go two frames past where you left off (you can actually do one).

In Operation: With a very short learning curve, this camera is a snap. Ergonomics are identical to an M6 with a grip. On P, you set it to your preferred aperture and it stays as close as it can without blowing your lowest hand-holdable shutter speed. Metering is dead-on, and the whole thing is so quiet most people think it’s digital — or ask when you are going to take the picture (although you already had). The shutter is completely vibration-free. Flash operation is perfect every time, even more accurate than TTL, because it is not thrown by subject reflectivity.

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Balance/feel: This camera balances really well and feels really solid, which is all you really need. The wheel that controls the aperture is on the top, and accessible by your right forefinger. It feels… good. It could use textured grips, but it’s not a big deal.

Durability: It’s a tank. Well, two (major) incidents. First was pulling the camera off my desk. Camera hit two drawer handles, put a nick in the floor. No damage. Christmas — got really loaded at the family party and dropped camera in the snow on the way back into the house. My sister came in the next day with the camera frozen in a sheet of ice. I chipped the ice off and very thoroughly dried it. No damage – and no fungus or haze 7 years later. It took the picture above after all of this! Because you have the luxury of a 46mm filter size with this camera, I strongly recommend screwing a B+W KR1.5 into the lens and leaving it there. When you have a filter screwed in, the lens barrel becomes almost completely air- and water-tight (all movement is within). As you can see above, it does not degrade lens performance to do so.

Long-term issues: Note that the 2-position shutter switch (focus… shoot) is rated for about 30,000 cycles – and it will eventually wear out. If you started with a new camera today, you would never physically be able to hit this limit. But since the oldest Hexars are now almost 25 years old, watch for this. The symptom is that the focus does not lock when you push the button halfway down in “loud” mode – and it becomes a problem for off-center subjects. To some extent, cleaning the switch can help, but the ultimate fix is to replace the dome switch with a similar DSLR part, which will set you back $100-150. But once you have that done, it seems unlikely that you will wear out the next switch.

Accessories: Hexars are no different to accessorize than any other compact, fixed-lens camera. But here are some suggestions:

  • Flash: HX-14 flash is the default choice. Not much flexibility, insecure mounting, no thyristor. Very tightly integrated with the camera and can automatically activate flashmatic mode. A Nikon SB-20 is a more powerful, more flexible option, but you need to set the PFL mode. Recently, I have had great success with the Nikon SB-30, which is small, power-efficient, flexible,
  • Filters: I would recommend a B+W MRC nano. Thin and repels everything.
  • Case: avoid the soft case.
  • Strap: get a wrist strap or a very thin neck strap. I would think about a Peak Designs modular strap that can exchange for a wrist strap or a neck strap.

Bottom Line: I think the ultimate test of the best all-around camera is what you would grab if told that you were leaving on an around-the-world trip and you had five minutes to pack. This would be mine.

 

 

 

Zoom lenses: good vs. not good vs. both

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This simple feeling… is beyond V’ger’s comprehension. No meaning… no hope… and, Jim, no answers. It’s asking questions: ‘Is my kit zoom lens good enough?’

In reality, we actually know little about zoom lenses except that the best ones (from a numerical standpoint) are very large, heavy, and expensive. Once you move into the enthusiast and kit versions, the question of whether or not they are good (or, more to the point, useful) is complex, subjective, and somehow optimistic.

General limitations

The struggle of zoom lenses, since basically forever, is designing a multifocal, focus-maintaining lens that is at least as good as any lens of the focal lengths covered, without being massively heavy or unimaginably expensive. This struggle is driven by four conditions of design, manufacturing, physics, and software.

  1. Design. Fixed focal length lenses have an inherent advantage because they are always going deliver high performance at low prices. Such lenses require computations at one focal length, have fewer parts, need less assembly labor, and require less glass. A zoom has to be good at a theoretically unlimited number of focal lengths between two extremes and has to maintain focus as it focal length changes.
  2. Manufacturing. The difference between a good lens and a great lens can be 0.01mm. Zoom lenses have numerous glass and precision molded plastic elements that have to work in formation at an infinite number of focal lengths between two extremes (say 14mm and 24mm). It is more difficult to make larger-diameter glass elements with great precision, and the more mechanical linkages exist in a lens (for example, ones that maintain focus through focal length changes), the more tolerances add up. Sometimes low moving mass and “slop” is built in to make lenses focus faster.
  3. Physics. More glass means more flare and dispersion, and zoom lenses have tons of glass. Flare can be mostly tamed via muticoating, but even so, dispersion adds up with the element counts. A 13-element lens with modern multicoating (losing ~1% per air-glass surface) can have a total loss of 25% of all the light coming into it.
  4. Software. This enters the picture in two ways: focus correction and image correction. On DSLRs and some mirrorless cameras, the AF Fine Tune function helps correct focus errors that occur with particular lenses and phase-detect autofocus. The difficulty with zooms is that the nature of focusing errors can change with each focal length, and dialing in a correction for one focal length for a lens can greatly improve images there but degrade images shot at other focal lengths. The second limitation arises in software correction of lens aberrations (distortion, vignetting/falloff, and sharpness). One cheat (or innovation, depending on how you look at it) is to let the camera make corrections that the lens design itself does not permit. This provides more freedom to design smaller, lighter, and cheaper lenses. But you can’t really reconstruct data that isn’t there – or bend it infinitely.

Why many enthusiasts have been suspicious of zooms

It mainly seems to be a thing with people 40 years old and up, who remember the bad old days. As to the history, in the 1970s, optical correction was not what it is today, and zooms got a really bad rap because things like the 43–86mm Nikkor were convenient but not optical superstars. The original zooms were two-touch, which allowed the easy setting of focal length and focus with two separate rings. If a lens mostly held focus as you changed focal length, it was a true “zoom;” if not, it was a varifocal (Nikon is, and long has been, an offender in calling varifocal lenses “zooms”). Zooms of that era were difficult to design, and it was a time where lens design was transitioning to more computerized methods. They worked for a lot of purposes, but given the natural male inclination to over-spec and compete with equipment, they were not taken very seriously.

In the late 1970s, manufacturers went to one-touch, where you could adjust focus and focal length with the same grip. The temptation was to conclude that you could just re-zoom, re-compose, and fire away, but the reality was that focus drift followed focal length changes, and if you didn’t bother to refocus, you could get slightly soft pictures. One-touch zooms also suffered from zoom creep: eventually, as the lens loosened up, pointing the camera up or down would cause the zoom mechanism (governed by front-back movement of the ring) to move on its own. This too, did not help perceptions, though there are some very good zooms of the 1970s and 1980s, including some third-party offerings like the Vivitar Series 1.

SLR manufacturers rediscovered the two-touch in the 1990s, when it became an advantageous design for autofocus lenses (an AF motor could turn a focusing ring but not also a zoom ring). And that is when they all backslid into selling varifocal lenses as “zooms;” the assumption being that the camera’s AF would correct the focus anyway. Although questionable from a marketing standpoint, autofocus helped assure that the new “zooms” would  be

The rise and fall of zooms (1999-2005)

If zooms had a heyday, it was from the late 1990s to the mid-2000s. Several things came together to make this happen:

  • Vis-a-vis prime lenses, zooms were more heavily telecentric than prime lenses. In simple terms, their design created the straight-on light rays that digital sensors like.
  • Advances in lens coating took away some of the performance penalties of using a large number of lens elements for image correction.
  • Prime lenses were getting little in the way of updates. This meant that the best ones were standing still, and others did not work as well as zooms with digital. Consider that it took Nikon 50 years to update the formula of its 50/1.4.

The prototypical lens of this era was the AF-s 17-35mm f/2.8 Nikkor, which was designed for the D1 cameras but was usable with contemporary film cameras too. This lens outperformed most primes within its focal length range, was solid, fast-focusing, and very  popular.

But just as every pendulum swings, the 2010s to the present are where the optical (but not necessarily total) performance level of cheap zooms took a little bit of a dive.

  • In a market with softening demand, maintaining competitive MSRPs for entry-level cameras and lenses required simpler and cheaper designs.
  • The processing power of digital cameras increased to the point where it became possible to correct for distortion, light falloff, and sharpness in-camera.
  • Increased emphasis on video, especially from mirrorless, demanded lenses that could focus quietly and continuously, driving toward lower moving mass.
  • The move by the market toward camera phones meant that the “burden” associated with separate cameras had to be minimized.

In other words, the ethic was (and is) using technology to make cheaper, lighter, and easier-to-make lenses acceptable, not so much to make good lenses better.

At the high-end of the lens lines, updated primes also began to exert pressure on the more expensive zoom lenses, especially where trends push toward small and light.

What is the quick and dirty way to identify “good” zooms?

When shopping for a zoom lens with high potential, this is the general hierarchy to predict (with some but not total certainty), where a lens fits on the performance curve.

— By effective aperture

  • Constant f/2.8 aperture – this generally means a pro-level lens. It also means big, heavy, and expensive.
  • Constant f/4 aperture – this is the high-end amateur or lower-end pro zoom. It takes a lot of engineering to keep the aperture constant on a zoom, and this type of lens generally has the best balance of performance, weight, and cost. Canon and Nikon both make this style of lens. These are not cheap, but they are much easier to live with than monster pro zooms.
  • Variable f/2.8-4  or 3.5-4.5 (1 stop aperture shift) – this lens type of lens generally has been optimized for compactness over speed. F/2.8 is really a bragging right; it’s only half a stop faster than f/3.5.
  • Variable f/3.5-5.6 (or f/6.8) (1.5+ stops) – when a manufacturer lets the maximum aperture float this much, it is generally an indicator that you should not be expecting world-beating performance. But you will get a lens that will do well in most circumstances and not break your back or budget in the process. These are actually the lenses that are fun to shoot with.

— By zoom range

This may sound deceptively simple, and maybe it oversimplifies, but it is a fairly good bet that where a modern lens has a zoom range of greater than 2.5-3x from short to long, it is is probably a “convenience” zoom rather than one oriented toward absolute performance.

Can “not-good” be good?

Yes. Despite having performance a notch or two below pro lenses, kit zooms can be quite good within some limits. First, in an era where photos are overwhelmingly likely to be shared on social media, and not printed, kit zooms are actually complete overkill. In fact, anything beyond an 8mp iPhone 6 might be complete overkill – the same way that a lot of expensive pro equipment in the 1970s was used by amateurs to generate 3.5×5 inch prints.

Second, even if you print, you only need about 6mp of real-world performance out of a lens to print a nice 8×10, which again is bigger than most prints made today. “Real world performance” means type of system resolution that DxOMark measures (lens performance plus body performance, moderated through focus accuracy). That might be a 12mp body and a midrange lens.

Third, you will still get really good results – though optimum performance may be ~3 f/stops from wide-open (f/8 vs. f/3.5 maximum) as opposed to (f/4 vs. 2.8 maximum). There is an old adage, “f/8 and be there,” but in reality, once a lens is stopped down even to f/6.3 (let alone 8), even a plastic meniscus lens will have performance approaching an expensive coated lens. Like vampire tears, the pro-lens advantage evaporates in bright sunlight.

Finally, especially for mirrorless cameras, some lenses have video performance that vastly outweighs whatever perceived deficiencies they have for other purposes. For example, you might conclude that the 16-50mm f/3.5-5.6 power zoom lens that comes with a Sony a6300 is terrible. It’s not terrible for still pictures (in no small part because it is one of the fastest-focusing lenses ever invented), but it really shines in video, where it can silently and reliably track moving subjects without introducing noise. And it’s also tiny.

Conclusion

To wrap up: the performance, utility, and fun factor of zoom lenses is actually pretty subjective. Try as many as you can. Pick the one that you like the best, so long as it does what you need it to do.

 

Konica M-Hexanon 28mm f/2.8

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The 28mm M-Hexanon, like the its focal length, occupies a strange space that is neither here nor there. I have never had good luck with 28mm lenses, if only because the angle is a little wide to be comfortable for close shots of people and a little narrow for some of the landscapes I shoot.

Only on the verge of selling mine (for lack of use since way back when I had an M8) did I shoot a bunch of tests with an M typ 240. This particular lens had been recollimated to be at exactly Leica spec (most lenses made before the M8 were not set up to hit the center of a flat sensor).

This piece will not editorialize much but instead show it like it is. Which is quite good, far better than I had remembered.

First, the obligatory “how sharp at a meter” exercise. This is f/2.8.

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Next: does it shoot good pictures of children? Yes.

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E poi – how is the bokeh? Strangely, it’s actually really good, especially for a wide lens. Here is the sequence f/2.8, 4, 5.6, 8.

Sunstars? Got ’em too. Here is f/2.8-8 (clockwise):

Gross resolving power (again, f/2.8-8):

And now, we laugh at your Elmarit-M!

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Flare resistance, same range:

Spherical distortion:

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Another test; can’t remember why. Seemed like a good idea at the time.

 

General verdict:

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50mm f/1.5 Zeiss Sonnar (1937): first

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Above: Zeiss Jena 5cm f/1.5 Sonnar (prewar; 1937 example of the 1932 design) on a Leica M typ 240 with an Amedeo dedicated 50mm adapter. This particular lens is almost 80 years old.

1. The story

The derivation of the trade name “Sonnar”(which may have less to do with Sonne than being a portmanteau of Sontheim am Neckar) reminds one of the the way that the Mr. Sparkle is a joint venture of the Matsumura Fishworks and the Tamaribuchi Heavy Manufacturing Concern. Be this as it may, the Sonnar had but one goal in life: crush Leitz’s fast lenses in an era where ISO 12 film was the norm. And that it amply did. Even today, the performance of this uncoated lens is impressive.

When the Sonnar arrived in 1931 (f/2.0) and 1932 (f/1.5), the Tessar (or Elmar) was the gold standard in normal lenses: a well-corrected triplet that, in an era lacking anti-reflective coatings, sneaked in a little more correction by cementing two pieces of glass together. When it came time to exceed f/2.8, though, the real competition began:

  • In 1889, Paul Rudolph, working for Carl Zeiss, determined that the best balance of contrast, correction, and cost was a three-element lens called an anastigmat (trade name: Protar).
  • In 1895, Rudolph invented the Planar, which was a highly-corrected symmetrical lens. It was shelved soon thereafter, no doubt on account of the low contrast that occurs with many air-to-glass surfaces.
  • In 1902, Zeiss released the Tessar, which provided more correction than an anastigmat (by adding a fourth element glued to the the third) without increasing the number of air-glass surfaces. The Tessar was technically inferior to the Planar, but it did not have the two extra air-glass surfaces (each robbing 10% of the light, compounded).
  • In 1925, Max Berek modified the Leitz Elmax, which had a 1-1-3 (cemented) arrangement into the Elmar, which bore a heavy resemblance to the Tessar, allowing for a good 35mm-format lens with fewer elements and less assembly labor.

In parallel universe (but still orbiting around Zeiss)

  • In 1916, an American (Charles Minor) started adding elements to the triplet, but just in the front. The result was the Gundlach Anastigmat, which had a blazingly fast f/1.9 aperture. The contemporary ads show that this was actually a cine lens.

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image credit: Central Camera 1936: Gundlach, Ultrastigmat, Bausch & Lomb, Verito Lenses; Packard via free images (license)

  • In 1922, Ludwig Berthele, working for Ernemann (of Ermanox fame) continued elaborating this into the Ernostar, which became on of the first plate lenses to hit f/1.8 (in 1924).

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Scan used by permission of Peter Naylor.

  • In 1926, Zeiss bought Ernemann and acquired Berthele in the deal.
  • In 1931, Berthele made the first f/2 Sonnar, which was a new lens with an old name. It was for 35mm format and had a 1-3-2 arrangement, with the second and third group cemented together.
  • In 1932, he made the f/1.5 version, which added an extra element to the rear group.
  • In 1936, caught off-balance, Leica licensed the Xenon, a symmetrical Double-Gauss design from Schneider, licensed in turn from Taylor-Hobson in England (the Series 0), in turn had been cribbed from the 1896 Planar.
  • In 1944-1945, the Zeiss plants were bombed back to the stone age.
  • In 1949, the Xenon was updated with coagulation-style lens coatings and became the Summarit.
  • In 1950, the Zeiss-Option Sonnars came out with a new computations.

The circle was now complete: the entire high-speed lens space was dominated by Zeiss designs and would continue to be – for pretty much all time. When you stop and think about it, until the advent of things like the 50/1.4G Nikkor, the history of high-speed lenses had been nearly nine decades decades of Sonnar and Planar clones.

Why did the Sonnar do so well? It’s not so complicated. It all boiled down to the number of air-to-glass interfaces. The classic triplet (the anastigmat) represented the best balance between correction, contrast, and cost. But adding more elements (to get more correction) meant more air-glass interfaces. And that meant less contrast and more flare. Zeiss increased the correction by cementing additional elements together to make a total of three groups. Leica could not do this because it did not have the intellectual property rights to do so. During WWII, Zeiss dabbled in coating its super-speed lenses, but it was not even really necessary given the Sonnar’s high transmission.

2. Using one today

These days, the Contax rangefinder is almost dead, 35mm film photography has gone all “Tony-Bennett-in-the-late 1990s,” and so the only place you’ll likely be using one of these is on a Leica body. Fortunately, it’s pretty easy to do. You just need the appropriate adapter. These are not particularly expensive for APS-C (although they do incorporate focusing helicoids); they are more expensive for Leica cameras because they need a mechanism to translate the movement of a 52.3mm lens to a camera whose rangefinder mechanism wants a 51.6mm normal lens (how two German companies known for their precision could get so sloppy about what constituted a “50mm” lens is baffling – but being a big-name German optical company means never having to say you’re sorry….).

By far, the best adapters for Leicas are made by Amedeo Muscelli, and of those, the best is that dedicated adapter for Contax 50mm rangefinder to Leica M. This is  not the usual lens with the reproduction of a Contax helicoid and focusing scale; rather, combines with the lens to make a unit that looks a bit like an old Elmar (allowing, of course, for the streamlined – dare we say phallic) shape of a Sonnar. The dedicated adapter focuses in the same direction as a Leica, at almost the same rate of distance change per unit of turn, and it has a lever, which can be critical if you are using a collapsible Zeiss lens (since with a traditional adapter, you are grasping the lens barrel to focus – something you can’t do with a collapsible lens). When your lens is dialed in, this adapter focuses amazingly accurately right down to 0.6m – a lot closer than any Contax did.

And how do you dial one in? If your lens is front-focusing, the simple answer is to remove the lens cell from the Contax barrel and unscrew the rear group slightly. It is never more than 1/4 turn, and you can maintain the setting by wrapping the threads of the rear group in Teflon tape and screwing it back in. Back it out about a 1mm (circumferentially) at a time, and check the focus on near and far objects. Do note that where a Sonnar has a lot of focus shift, you’re going to have to choose whether to

  1. Have the lens front focus at f/1.5, reach focus at f/2.8-4 ,and hit focus at f/5.6 and smaller
  2. Have the lens focus dead-on at f/1.5, miss at f/2-4, and become usable again at f/5.6 and on.

3. Observations

The first observation is that finding a prewar f/1.5 Sonnar that is not totally trashed is not particularly easy. Fortunately, at least cleaning marks are not an issue on uncoated lenses unless someone used Soft Scrub as an optical cleaner. Which does happen from time to time.

The second is that in the central part of the frame, this lens is very, very sharp. It has decent performance at f/1.5 if you optimize for that aperture, loses precise focus from f/2.8-f/4, and comes roaring back at f/6.3. If you keep with the original collimation (or an approximation of it, you get really sharp pictures around f/2.4, getting better through f/8.

The third is that the coatings on postwar Sonnars are not moving the ball much in terms of performance. Because this was the last fast Sonnar I obtained, it’s easier to compare this to the 1961 Carl Zeiss version. The 1937 model performs similarly in most ways. It is very slightly softer, with contrast that is almost at the level of a 1977 Jupiter-3.

Flare is only slightly improved by coatings, and they do not resolve the “rainbow circle” flare that afflicts every Sonnars (even multicoated Sonnetars) when a point light source is just out-of-frame. The one unique failure mode is strong side lighting (from the looks of it between 75 and 90 degrees to the lens axis), which can cause a veil across the entire surface. This also happens to a lesser degree with postwar Sonnars and copies, just not quite to the same degree.

Overall performance is strikingly close to the postwar, if you allow for slightly improved spherical aberration on the older lens. The postwar version is a tiny bit sharper, but seems clear that this comes at the expense of bokeh, which goes from smooth disks to ringed disks. If you care about that stuff.

4. Roy Batty

The f/1.5 Sonnar was the proverbial candle that burned twice as bright, and by 1962 it was essentially extinct. The “twice as bright” part is doubly applicable to the 1960-1962 Car That it was so widely copied in the postwar era is puzzling. Granted, German patents were handed over to the Japanese, but in terms of sheer performance with coatings, there were already better lenses to copy (like the Xenon). Canon, Nikon, and Zunow all made their own versions. The Soviets made one too. Perhaps there was a “prestige” element to the Contax that was desirable to copy (though you would not have the all-important brand name). Or perhaps there was something about the mechanical design of a 3-group lens such that the cost of machining extra parts for 6 groups cost more than triple-cementing rwo groups. The world may never know. The fetishization of the Sonnar did not really get started until the mid-2000s and by then, it was based more on imperfection and “look” than a perception that it was actually better.

Conclusion

The prewar f/1.5 Sonnar is a worthy lens, though its relative scarcity does not exactly make it a value leader compared to postwar variants. As with any 50mm Sonnar, as long as you take care to control the placement of light sources, it can be another creative tool, if not a broader-use lens.

Canon 50mm f/1.2 LTM: not screwmounting around

As you contemplate modern lenses, It is difficult to associate these optics with the proud civilizations that created them: Tokyo, Rochester, Sendai, Jena. They worshipped image quality, because it is strength that makes all other values possible. No picture survives without it. Who knows what delicate objective lenses have died out of the world, for want of the strength to continue. 

It’s a long way from the Canon 7sz to Andre Agassi, from the Serenar to the EOS Kiss Merkur XR4ti (…or whatever the amateur model of the week is). Canon used to be a hard-core producer of Leica knockoffs, many of which were more functional, convenient, and reliable than the rickety prewar designs that Leica kept elaborating. The Canon P was a standout, as were the VI-L and the 7 series.

The Canon 50mm f/1.2 (September 1956… can you believe that it is now almost 60 years old?) was the company’s penultimate halo lens. It came out with the VT (not Deluxe), and it would not be surpassed until 1961 with the Canon 7 and its 50/0.95 Dream Lens (from a size, weight, and cost standpoint, dream is clearly defined broadly to include nightmare). Ironically, the 50/1.2 cost more than the 50/0.95. Modern Canon lenses are quite good, but they don’t have that certain fun factor to them.

Synergies. This is a new thesis on my part, but I am starting to suspect that the M typ 240 and 246 tend to interact with lenses in ways that might not be immediately intuitive. Some lenses seem to work unexpectedly well with the color sensor (possibly the demosaic-ing algorithm accidentally boosting sharpness). Many lenses work better than expected with the Monochrom camera — likely because the color-bind sensor is not bothered as much by chromatic aberration. The “why” these things happen is probably insoluble; it is merely interesting that they do. And yes, some dog lenses do stay dogs, and some lenses have bad corners to f/8. Nulla regula sine exceptione.

Look and feel. Perhaps “Carré Otis” is the best way to express the relationship between the size of this lens and Canon’s more common 50mm lenses (2.8, 2.2, 1.9, 1.8, 1.5): generously proportioned, slightly flaky, and exhibiting certain, ahem, virtues.

The finish of the 50/1.2 is typical mid-to-late Canon that came into vogue in February 1956 with the 50mm f/1.8 mark II: a black enamel focusing ring and sandblasted chrome aperture ring and distance/DOF scale. This is much more pleasing than Canon’s contemporaneous all-black lenses (like the 35/1.5, 35/2, 100/3.5, 100/2, and 135/3.5), whose finish looks good in smaller lenses and feels chintzy in larger ones. But the affect with the 50/1.2 is solid. It will keep your M typ 240 on balance.

The focusing effort is heavy, and even the aperture turning is heavy. Unless, of course, lubricant has leaked out onto the aperture blades. The focusing pitch is very slow. Even the interesting push-button infinity lever takes a deliberate effort to dislodge. Is there a problem with any of this? No. Will you have issues tracking fast motion or switching from near-to-far subjects (or vice-versa) as if you were a D700? Yes.

Flare and use with filters. The first thing you have to remember with this lens is that you are dealing with an SLR-sized front element that sits very close to the front of the filter ring, seven elements, and single lens coatings from the mid-1950s. This isn’t going to flare, right?! Really, cleaning marks are the least of your problems here.

The big (physical) hazard with this lens is filters – as in don’t tighten down a filter without checking the clearance between the filter and the front lens element. If you want use conventional filters, you will likely need to use an empty ring as a spacer or fit a rubber o-ring around the threads on the filter. The only alternative is to use Canon RF filters, which are expensive and present a flush glass surface on the front of the lens. Not only does cabin your choices for lens hoods, it also presents ample opportunity for sidelight flare. Like the picture below (and let’s be fair – this is shot outdoors with floodlights everywhere). But be sure to use some kind of hood if you can.

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Canon filter ghosting (at f/1.2). All hell is breaking loose here (not surprising with Christmas lights a scant two feet from the lens), but it’s not all bad, given the motif:

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On balance, it is better to use a filter if you don’t want to deal with the rickety Canon metal lens caps, which never want to stay on. Just watch how you use it, and if you can space it correctly, consider an MRC.

General optical performance. On an M, at 24mp, the 50/1.2 really acts like Beauty and the Beast. At its largest aperture, it has microscopic depth of field, though with practice, you can tell where it is going to land. It does what most other super-fast spherical lenses do: it front focuses at wider apertures and settles down at middle ones. Every one of the three copies I have owned seems to have had slight differences in the midpoint of depth of field at close ranges and large apertures, which is not surprising. But this is par for the course; all fast 50mm lenses are testy on Leica rangefinders. As you start stopping down, the 50/1.2 becomes exponentially sharper. F/1.4 is light years better than 1.2; f/2.8 is orders of magnitude better yet.

Rather than dragging through every optical trait one at a time, let’s take it at f/1.2. Soft contrast, heavy vignetting, reasonable resolution of details, with a field that seems to curve at the edges toward the camera. This vignetting persists, even when the lens is coded as a Leica Noctilux. To be fair, this was more than enough for most 35mm film use. A lens like the Canon 50/1.2 would be used at night, where contrast would be high. It was not designed for thin depth-of-field fetishism. You can click on the picture below for a full-sized image.

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The picture at the top of this article is also shot at f/1.2. In terms of controlling bokeh, if you are into that thing, this is yet another lens where your best bokeh is achieved by (a) getting the subject as close as possible and (b) getting the background as far away as possible. Not to belabor a point from the previous article (on the MS-Sonnetar), but an easy and almost unavoidable rule of thumb is that the better a lens performs wide-open, the worse the bokeh. The list of these suppressed lenses is long and distinguished: this Canon, almost every Noctilux, the Hexanon Limited, the Nokton 1.1, the Nikkor 1.1, and basically any lens faster than f/1.4.

The next click, f/1.4, is a touch more contrasty, and is still a good setting to use in harsh nighttime conditions. Take a look at the field curvature here – there is no way the Gummi Bear wrapper should be so close to being in focus like the boys. Actually, it seems unlikely that both boys should be in focus, but there you have it. And here you also have the bokeh vibe. As in vibration.

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Just for fun, below is one shot wide-open with an M8 (you can click on it to see it at full size):

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Stopping down to f/2 gives better results yet – and the focusing point is now exactly where you would expect it to be. And here is your bokeh test outdoors. This is essentially minimum focusing distance with a background that is 50m away.

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At f/2.8, the lens is starting to hit its stride. Especially with the M set for emulation of the Leica 50/1.2, the lighting evens up, the sharpness goes up significantly, and the field flattens a bit. Although this begs the question of getting a slower lens and shooting more wide-open, with these old lenses, you are often better off with a fast lens stopped down than a slow lens wide-open. Also, the big old glass looks cooler and makes child ward nurses less likely to think you are using some kind of super-high-tech digital camera to document medical procedures (when you’re actually just bored).

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At f/4, performance starts to max out (like the 1.2 shot, you can click on the one below to get a full-sized image). You almost go into double-take mode because a good example of the lens looks sharper than lot of modern glass. I’m thinking particularly of the 50/1.4 AF Nikkor, which the Canon crushes – and likely because the Nikon is usually tied to a somewhat limited AF system (phase detect systems seem pretty much incapable of compensating for the focus shift that occurs when a lens stops down).

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F/8 is where performance starts to degrade a little bit (see the full-sized image). Sharpness starts to decline. People take on cartoonish, ascetic, or vampiric features. Bring your gloves, lightsabers, and garlic.

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Conclusion? This lens was sold as the premium lens on a lot of Canon cameras – and in some ways a “bragging rights” lens vis-à-vis Leica and Nikon. The performance at f/1.2 is reasonable but not world-beating; but given limits seen even in digital M shutters (1/4000 sec), you would rarely be trying to shoot this lens wide-open in daylight. At least absent a neutral-density filter.

The pricing of this lens is all over the place; super-clean examples (from a cosmetic standpoint) seem to command a hefty premium, but almost all will exhibit microscopic scratches (cleaning marks), and oil haze is a recurring theme (and it is fairly destructive to these lenses’ coatings). But as with a lot of things, cosmetics are not indicative of performance; you never know whether a lens has been abused over the years until you actually try it.

Be ready to poke around through multiple examples to get one that works really well; keep an open mind about the condition of the coatings; what makes these lenses flare badly has little to do with the coatings but rather with the hazards of having that really big front element.