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.

Did we ever really understand film?

One of the coolest developments ever. But do we know what to do with it?

The word Columbusing has become a thing for describing the phenomenon by which a person believes that he is discovering something that in reality had always existed. It certainly seems possible that this is happening when people try to write reviews of cameras or films. I have now read hundreds of the film reviews in particular, and as an old-time Gen Xer, I realize that these writers are in a position to do one thing: demonstrate whether they as photographers can get a good image out of the material. The rest is of limited use.

Cachet qua cachet

Often, but not always a film review article will take this rough agenda. I think if you go back on my old site via the Wayback Machine, you may even find me doing this (though at the time I was writing about film, the cachet step wasn’t there, since almost all of today’s discontinued films were still sold then… In the early 2000s, when most of those pages were being written, film was just starting its tailspin.

Cachet signaling. This is the prelude. Usually consists of a description discussing how “those in the know” understand Film X (likely discontinued before the author ever picked up a camera, or in some cases was born), some information cobbled together from Google searches, and how the author came into possession of the now-expired film of unknown history, storage conditions, etc.

The low-sample test. Film X is frequently shot with a camera of significant vintage and unknown meter accuracy, sometimes used in conjunction with a meter of a certain age. Film is either commercially processed or done once, whether by the book, by guess, or by the Massive Film Development Chart (which can also be a crapshoot). Bonus points are awarded for random-guess compensations for the film’s age. Double secret bonus points if a restrainer is involved.

Abstraction to what the film is “about.” Author concludes that Film X is magical for xyz reason and that you should pay some scalper (or re-labeler) big time to get it.

Just stop here for a second. I am impressed at how good some of these writers are at photography. They have an eye. They can take a good picture and make a pleasing output. But nothing else they are doing is very instructive because their experience is not accurate or repeatable.

Call it a generational thing (or maybe half-generational) thing. As a group, Baby Boomers walked away from film photography and neither preserved nor transmitted decades of institutional knowledge on the subject. Most Gen X people know film as something you would shoot and take in to be processed. Even for them, unless they made pictures professionally or for a hobby, film photography became disposable as soon as digital became cheap. Which brings us to the millennial children of boomers: a knowledge discontinuity leads to satisfying feelings of discovery. But just as Columbus’ setting foot on Hispaniola did not mean a “new world” for peoples who were already there, superficial film reviews provide little (and really no) novel information.

Do b/w films really have looks?

But let’s back up to something in the cold light of day: with a few exceptions that came really late in the day, film was never really designed to have an aesthetic “look.” It was always designed to have a function. That drove aesthetics. To a point.

Almost 20 years into the 21st century, conventional black-and-white film has no real mysteries. For most of recorded history, film followed a pretty regimented set of tradeoffs: slower film had finer grain and finer tonal rendition. Things got grainier and lost dynamic range as film increased in speed. Although tablet grained b/w films helped increase performance, most of what you see in black and white films is the product of design tradeoffs rather than some deliberate aesthetic proposition.

Recall that the basis of film photography was science. I would suggest that, after a lot of time developing film, the differences between films of a given type and speed are actually relatively minor compared to the effects of varying developer, time, temperature, and agitation. Let’s take an example: Tri-X and TMY are different films, right, Tri-X with an S curve and TMY straight? Here is that classic Tri-X characteristic curve.

Ok, and here is your philistinic, “robot,” “soulless,” TMY, also developed in D-76:

Now develop both in T-Max developer and overlay the curves (black is TX, red is TMY). Don’t have a heart attack, but there are far more similarities than differences in response. Maybe a minute’s difference in developing time. Oh no…

But wow, this was like the holy of holy in differences in “look,” right?Nothing should be very surprising here; tablet-shaped film grains aside, the reaction of silver halide molecules to photons has not changed at all in 150 years of film photography.

So today, some films are grainier than others, some are contrastier than others, some are faster than others, normalized for a developer. But the choice and deployment of developer (if not also every other step of the output chain) can hugely influence or obliterate the “curve” which is the seat of the “look.” In other words, film is just a variable, and from a tone and grain standpoint, perhaps it’s far less of one than we thought.

Did consumers ever actually understand color film?

When you get to color film, things get more complicated because these start with silver halide, which is bleached out and functionally replaced with organic dyes. Color dyes are fickle.

When it was still made in a bunch of varieties, color negative film itself was somewhat inscrutable to anyone but pros and the very serious amateur. Moderately skilled (or more accurately, moderately informed) photographers knew that some types of film were better at skin tones than others (such as Kodak Vericolor III), but for the Joe Average, who had a skill level equivalent to most people writing about film, pretty much every C-41 negative film went through a minilab/printer, which was a highly automated way for drugstore personnel to make magic from your little canister and hopefully not destroy the negatives in the process. If you were a pro, you would send your film out to a pro lab where professionals would make magic from your little canisters of film and hopefully not destroy the negatives in the process.

Although competing brands of film within a certain type (color negative, color slide) used different methods of getting to the “right” color, skin tones were the pivot. Color, oddly, never really got more differentiated than high-contrast/saturation (Velvia, Portra VC, etc.) and regular (Provia, Ektachrome, Portra NC…).

Did you ever notice how much people hate on Kodak ProImage 100 for being excessively grainy and undersaturated? Aside from slight desaturation, it’s essentially where 100-speed film was when people stopped putting money into developing 100-speed consumer color film. The point-and-shoot camera – typically with a slow lens – put a high premium on 400-speed performance, and that’s where manufacturers went. The faster film got to the point where Kodak HD200 and 400 were far smoother than good old GA-135. Here is an easy conversion from consumer to prosumer to pro:

• Gold 100 gen 4 » Extinct » ProImage 100 (rebalanced)
• Gold 200 gen X » ColorPlus
• Gold 400 gen 6 » some other steps » Gold Max 400
• Ektar 125 » Ektar 100 » Royal Gold 100 » Extinct » Ektar 100
• Royal Gold 200 » Kodak HD200 » Extinct
• Ektar 400 » Royal Gold 400 » Kodak HD400 » Extinct
• Vericolor III » Portra 160NC » New Portra 160
• Portra 160VC » Replaced by New Portra 160
• Portra 400NC » New Portra 400
• Portra 400VC » Replaced by New Portra 400
• Portra 400UC » Extinct

Slide film might have been even more mysterious — and represented a medium that spanned the absolute best professional photography and the worst amateur work feared by man. And nothing in between. You either had it or you didn’t. Transparency film was sold in large quantities to tourists and people wanting to shoot color in the really old days. Which made a lot of sense when a goddamn color photograph was a big deal, even if it took 6/12/36 exposures to get one good one. Kodachrome was a tri-layer black and white film that got an infusion of dye during processing. Slow, sharp, permanent, and capable of delivering a nice looking picture assuming the constellations were lined up. And if they weren’t, blown highlights, blocked shadows, and blue. Slides were the ultimate measure-twice, cut-once medium — but few people bothered to measure. Ektachrome and Fujichrome made it cheaper and easier to generate huge boxes of vacation slides that no one wanted to see — and ultimately faded out transparencies that no one could see.

Today, unless you plan to look at tiny positives backlit by homemade ground glass after the Zombie Apocalypse, or have brought some friends over, Buffalo Bill style, to watch vacation pictures projected on a screen (“it puts the slides in the carousel”), digital photography does everything slide film did – but better. Where you can vary the ISO, get more dynamic range, infinitely adjust contrast and saturation, and crop at will, it’s hard to make the argument that Ektachrome came back for anything but nostalgia and motion pictures. Which is a worthy reason. Let’s just not pretend it’s scientific.

In addition to allowing things to happen that could never happen with a filter-based minilab, the rise of the Fuji Frontier in the late 1990s was really the nail in the coffin of film-awareness. With hyper-sharpening, dynamic range compression, and ultimately, smart automatic operation, the Frontier made every photo look perfect. The technology is not unlike how people deal with negatives today: develop, scan, print (in the case of the Frontier, onto photo paper, using a laser). Today, the Frontier’s weirdly regimented view of the world lives on in the hackneyed wedding presets used on Lightroom by an army of semiprofessional shooters using Canon 5Ds.

And if you remember old film packaging, there is the warning that “color dyes in time may fade” (Gospel of Eastman Kodak, K41:1). Everything on earth is capable of influencing the colors and balance of color films: lot, storage temperature, age, exposure, environmental radiation, magnetic fluids, and phlogiston. The same goes for the output media, which if you’ve seen old Fujichrome slides, can be interesting.

That’s part of why the support infrastructure was so complicated, whether it was a minilab computer or CC10, 20, and 30 filters in cyan, magenta, and yellow. And why pros – once they had a particular lot of film dialed in – like a particular lot of Ektachrome – they stayed with it as much as possible. And even pros sometimes had to lean on color correction experts at labs to make every one of those Glamour Shots® perfect.

Conclusion

Hopefully you have not found this discussion offensive, but as an almost old person, I am not at all hesitant to tell you that everyone in their 20s has a Dunning-Kruger delusion when it comes to the technical aspects of photography. As someone who was there for the twilight of mainstream film photography, I would mostly observe that until the bitter end, film R&D was aimed at making the medium a neutral one that could be manipulated via development, printing, or even scanning – and that today, you can easily mistake random errors for some intentional aesthetic balance.