Archive | October 2013

Leica M Typ 240: Part 4 (SF-58 flash and 14489 diffuser)

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M typ 240, SF-58 bounced off window(!)

Calling the questions. The Leicadoxy often questions why anyone would ever use a flash – or why Leica makes flash units for M cameras. The answer is that it’s easier to sell a $11,000 camera/lens/flash combination if it even very occasionally it creates pleasing pictures of children or grandchildren.

Even within this deviant universe in which xenon light exists outside fire alert flashers, the SF-58 is a curiosity: why would I pay $630 for a flash that Metz usually sells for about $400? The SF-58 does not get much play in terms of reviews or even admissions by Leica users that they own/use this unit. The SF-58 is actually not a bad addition to a M setup. There are three reasons.

1.  The SF-58 is the only shoe mount flash that fully integrates with the new M’s TTL system.

2.  High-speed sync.

3.  Did I mention high-speed sync?

Leica has never really had an acceptable flash system for the digital M series – until now.  You could use a generic hot shoe flash with the camera in manual exposure mode. You could use a Nikon-style automatic flash to trigger the ready light sync speed in AE. If you wanted exposure compensation but were willing to live with CR123a batteries, low power, slow double-popping, and no tilt, you could buy the SF-24D. If you wanted tilt but were willing to give up exposure compensation, it was the Metz 54MZ-3 or -4. The SF-58 came in with the Leica S – but on an M8 or M9, it was still fairly crippled for daylight fill.  The M now has high-speed sync that allows flash exposures up to 1/4000 second.

Benefits. The SF-58 – manufactured by Metz – has the following other features that are useful:

  • The menus are possibly the simplest on any Metz digital flash.
  • It can run on NiMH AA batteries (unlike some other Metz products like the 45 series) or a 12V input. It has a low-battery warning so that you don’t overdrain the batteries and cause polarity reversal in rechargeables.
  • It has two flash heads. The secondary flash head can automatically activate when the main flash head is tilted – and can be set for 1/1, 1/2, or 1/4 power.
  • It has a “soft” mode that can set the main reflector to one step wider than the lens (it can key to the lens selected on the camera – whether selected by 6-bit code or manually).
  • In addition to TTL and M(anual), It can be set to (A)utomatic, which allows it to be used on other cameras. On a Nikon D700, for example, the flash will trigger the ready light on the camera and work properly set in this mode (aperture information is not transmitted to the flash, so there is no distance information. Oddly, some older Nikon TTL flashes (made for film cameras) are the ones the freak out Nikon DSLRs.
  • It can be set to slave mode.
  • The basic contact arrangement is the same as a Nikon AF-TTL flash, so you can use Nikon off-camera TTL cords.
  • Like other Metz products, the color is accurate and very slightly on the warm side.
  • Like other Metz products, the exposure is dead-on in TTL or automatic modes.
  • Like other Metz products, the guide number is actually accurate.

Annoyances. It has the following features that are of marginal usefulness:

  • An AF-assist light (apparently intended for the S series).
  • A screw-lock flash foot. This actually locks via a locking pin in the hot shoe, but the way it is deployed is by turning a ring not unlike the ones you would tighten to the camera by friction. Nikon has the better idea – the flip-lock shoe.
  • A four-battery chamber – although recycling time is not generally a big problem with this flash, it would be nice to have a fifth battery like some other flashes do – if only to address the use of 1.2V rechargeables.
  • A multiple flash feature. Strobe effects are so 1980s.
  • A pop-out diffuser card that is not really large enough to work.
  • Massive size. It is not as fat and top-heavy as an older 54MZ, but it is fairly large compared to an M. Using lithium AA batteries achieves better balance.
  • The flash includes an AF-assist light that has no function on a digital M.

Hazards. It bears the following cautions:

  • The distance scale does not change automatically when you change the camera’s aperture (apparently, it does not have access to the estimated aperture information from the camera’s “third eye”).
  • When using AE and auto ISO, note that the flash going into ready mode will activate the last ISO actually used by the camera in manual mode. So to set up, go to manual, set the ISO where you want it, shoot a frame or two, and then go back to your usual automatic settings.
  • Because many SF-58s will have sat in storage for up to years, leave the flash on with batteries in for a couple of hours when first putting it in to service. You may experience strange behavior with auto-zoom, the AF assist light, and the distance indicator while the flash is powering up for the very first time.
  • The small rubber cover for the USB port will eventually get pulled out in your camera bag. It would be a good idea to tape it down.
  • As on any flash, take care not to scratch the fresnel lenses on the flash head.

Operation. The SF-58 is actually fairly pleasant to use, and unlike a Nikon SB-800 (or even previous Metz flashes), all of the useful settings are at your fingertips. Pressing the “Mode” button pulls up the list of modes, which are then activated by the two soft arrow keys (pressing the “Mode” button moves up the list toward TTL). “Set” gives you instant access to flash exposure compensation, zoom, aperture, and where not connected to a camera, ISO. “Menu” gives you the short list of customizable functions (dual flash, beeping after exposure, standby time, modeling light, key lock, soft mode, m/ft.

Quality of operation. As you would expect with a flash this expensive, there is very little to complain about.

  • Metz flashes have no problems delivering power and accurate exposure – and where Metz is aware of a manufacturer’s actual protocols, it is capable of making completely compatible flashes (on the other hand, where it has to reverse-engineer Nikon’s flash protocols, for example, things are not so good).  The flash omits light at a consistent temperature (except in HSS, discussed below).
  • The zoom reflector works adequately to account for various focal lengths but works best where the flash is set to the “soft” mode. This reduces maximum power by going a step down in focal length (for example, a 35mm setting on “soft” would be 28mm – reducing the effective guide number. I would strongly recommend making sure that “soft” is not set for outdoor shots, where especially with HSS, you need all the flash power you can get.
  • The handshake with the camera is much harder to screw up than with the M8 and M9. When you initiate metering for flash, it is necessary to let the camera communicate with the flash so that it knows the flash is there (the camera transmits any known focal length information and the selected ISO in the process). Shooting too fast after powering up the camera can cause a miss, which usually results in a correct ambient exposure of a couple of seconds, followed by the obligatory noise reduction (dark frame subtraction). Fortunately, it is much harder to fool the M typ 240, and the only other way to blow the exposure is to shoot when the flash is not ready.
  • Recycling time with NiMH batteries is a steady 4.5 seconds (from a full-power, empty-the-capacitors manual flash).
  • The built-in reflector card is adequate to make a nice “from the top” light on faces – pulling it out also deploys the folding 18mm diffuser.

Design. The SF-58’s physical configuration is a taller, lighter, slimmer version of a Metz 54 – and is characteristic of the 58 series (Metz also makes versions of this flash for other digital camera brands).

High speed sync (HSS). This is, after all, why you would buy this flash. Since the late 20th century, Nikon and Canon owners have enjoyed HSS, which allows flash synchronization beyond the normal sync speed. HSS is a bit of artifice. Focal plane shutters (such as the ones in Leica Ms and SLRs) expose the entire sensor, all at once, up to a certain speed, beyond which they expose a slit that moves across the sensor at a constant speed. The maximum sync speed is the highest speed at which the whole sensor is exposed at the same time. At that (or a slower) speed, when the shutter is all the way open, the flash fires. The problem is that at speeds higher than the normal sync speed, the flash would fire when the slit was in one place and would be extinguished before other parts of the sensor were exposed. HSS sidesteps the limitation of the slit by pulsing the flash so that as a smaller-than-the-whole-frame slit travels the sensor, it is always illuminated.

HSS has two principal side effects. One is that the available flash power diminishes (and the SF-58 will indicate the effective range in HSS). The other is that the color temperature will decrease (from white toward a warmer balance).

On the M240, HSS is very fluid; it is automatically activated when needed. In general, M240 fill flash is fairly good, though occasionally you will dial-down the ambient exposure or dial-up the flash, depending on how backlit the subject is. My impression, and this is subject to some further testing, is that in Auto ISO, the preflash sometimes tells the camera how to drop the ISO to avoid using HSS at all.

The M240’s fill flash performance in general is quite good. Sometimes you might dial-down the background or dial up the flash (for backlighting) – but in general, the system works.

SF-58, 1/1000 sec, didymium filter

SF-58, 1/1000 sec, didymium filter

SF-58, 1/250 sec, toddler exploitation filter

SF-58, 1/250 sec, toddler exploitation filter

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SF-58, 1/500 sec, didymium filter

The 14489 diffuser. At $29, this is either (a) the cheapest Leica accessory ever made or (b) the most obscenely expensive piece of thermoplastic sold. The physical design is a bit off; unlike the typical diffuser, this is a flat piece of translucent plastic that snaps over the main flash lens, and the inside has a diffusion grid.  Rather than sliding into a track, it attaches via two tabs at the top. The tabs activate a microswitch in the the head that changes the reflector position. This gives a zoom position of “16mm.” The diffuser does two things: (1) it lowers the light temperature slightly (making it warmer) and (2) kills flash vignetting. In doing so, it cuts the maximum flash power by about half. In the worst case, this diffuser protects the main flash head – but beware that when snapped on, it is fairly easy to dislodged.

Upshot. The SF-58 is expensive, but it is hard to argue with the capabilities that the flash brings to the M240.

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Leica M Typ 240: Part 3a (simple b/w conversion)

This is a simple conversion using LR 4 at the default settings. This was taken with a 21-35mm M-Hexanon at 35mm and f/5.6. Overall picture has been perspective corrected (and certainly not perfectly – just enough to make the error less obnoxious); details are from the uncorrected file. This piece may be merged into another one of the parts. Note that the compression used by WordPress tends to flatten the whites and blacks very slightly.

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Leica M Typ 240: Part 3 (pixels)

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Above: 35mm Summilux ASPH (non-FLE), wide-open
***Note: click on pictures to enlarge

You’re going to lose your religious beliefs. There is a lot of talk about “rendering” and something special with the M9 and its CCD. When these people use an M long enough (and it does not take that long), they will wonder why they tolerated the Atari-age eletronics or the low-light performance (or lack thereof).

Challenges to image quality

The fact is that the Leica M’s 24mp is verging on the usable resolution of a 6×4.5 negative at ISO 400 and above. With no antialiasing filter and a new pixel well solution, it actually presents fairly stunning results. The catch, sadly is that three things hold back the camera.

a. Limits in the lenses.  One limitation is older lenses (i.e., those before the late 1990s). Though charming in contrast and focus characteristics, they resolve less than the sensor can. And where they have uncorrected spherical aberration, they exhibit very obvious focus shift. This makes the extra resolution over the M9 (15% linear in each dimension) seem a fairly marginal proposition. The concept that comes to mind, though not completely apposite, is empty magnification in microscopy. You can multiply the pixels as much as you want – but in the end, the lens is not delivering enough information to make use of them. This is part of the problem with the D800E (and soon-to-be Sony A7r)

b. The human factor. The other problem is poor technique. With high pixel density, errors like poor focusing and camera shake are more apparent. Lenses of 90mm and up are difficult to use with the M’s rangefinder. They are already challenged because they are in the range where an SLR (or an EVF) does better with focusing. But the killer is camera shake. A good rule of thumb with the M is to set a shutter speed that is at least double the reciprocal of the lens length.  A low-speed threshold of 1/125 second for Auto ISO is advisable.

c. Moiré. The new system uses considerably less aggressive moiré removal than the M8 and M9. As a result, the smallest resolvable details in shots (like the texture of bricks, for example) may pick up a little moiré sparkle. This is the downside of the clamoring to eliminate antialiasing filters.

200 200-detail

Downsampling

The thing about having a very high resolution sensor is that it allows you to throw away data to get a better result. And it is fairly well documented that a large image downsampled to a smaller size is typically better than a small image that started that size. This is why you lose nothing with old lenses when going to 24mp. It also enables pretty spectacular high-ISO peformance.

High-ISO performance

The short of it is that the M crushes the M8 and M9 in high-ISO performance. There is plenty of quantification available on the interwebs, but here are the key things I have noted are:

  • High-ISO (≤2500) is almost exactly the same as the D700 – except that you have twice as many pixels in play.
  • ISO 3200 is completely usable, but dynamic range starts taking a beating. At a pixel level, it is still comparable to a Fuji X-Pro 1.
  • ISO 6400 has regular pattern noise but is no worse than Tri-X pan film in b/w; no worse than scanned 400 color film.

If you want some concrete information on the last point, here is an example from where I accidentally shot a picture in broad daylight at ISO 6400 with an SF-58 flash. It’s a small miracle this worked at all, but here is the Tri-X detail at 4 stops more sensitive (and this is straight out of LR, with no attempt to fix the noise):

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As with all other cameras, the lower the color temperature (i.e., incandescent light), the more noisy high ISOs become. This is due in part to the fact that auto white balance is trying to raise a blue channel that is at the noise limit.

Auto ISO weirdness

The fact that Auto-ISO doesn’t work for manual shutter speeds is well documented. As is the fact that your choices are either to go with the reciprocal of the focal length (if a lens is coded or selected) or an arbitrary shutter speed limit.  One wrinkle that is not documented is what happens with flash.  When the flash (whether Leica or Nikon-style) tells the camera it is ready, the ISO changes to the last value set in manual mode. To get to the picture above, I had previously used the 6400 speed to shoot at night. Taking a fill-flash shot during the day caused the ISO to change from auto to 6400. If you plan to use fill, I would recommend taking a couple of shots at ISO 800 in manual shutter speed mode to use that speed.

As against the M8/M9

The M is thoroughly modern in its sensor performance, whether measured as a function of resolving power or low-light performance. The move to CMOS, though lamented by the hard core of M9 users, has produced no measurable change in “rendering” and has increased low-light performance at least a couple of stops (and the collateral effect is to allow video). Not bad.

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