View Full Version : M6 infinity focus RF allignment needed?
Hi everyone. I'm a longtime SLR shooter and occasional RF user, and have use of an M6 (non-TTL) and 50 f2 Summicron for the weekend. As I was shooting my first roll of film, I noticed that the rangefinder patch image does not come together completely (in horiziontally) at infinity (checked at night with the moon). My $50 Canon QL-GIII patch image is perfectly aligned at infinity.
Should I presume that the M6 RF is in need of alignment? I haven't yet had a chance to check any negatives/slides for sharpness at infinity -- if the RF image doesn't come together, will the image on film likely be out of focus? And if so, will this also affect focus at intermediate distances (where the patch image _does_ come together as expected). I should add that the body with a 90 f2.8 Elmarit exhibits the same behavior, though not quite so severely, so I don't believe it's a lens issue.
Thanks very much in advance...aa.
If the camera is a rental and you're not too convinced of its operability, and if you can return it, go ahead and take it back to the renter.
In general terms, if the patch comes together in one direction... you're still safe. In my Canonet, the vertical is a little off at infinity, but the horizontal isn't, and my photos have come out well.
Where did you rent this camera from?
Have fun anyway! :)
Thanks for the quick reply. This particular body/lens isn't a rental -- it's being sold on consignment, and I arranged to borrow it for the weekend. Frankly I doubt I'm in the market for it -- I have a substantial investment in Nikon SLR gear (both film and digital), and the notion of making a parallel investment in Leica gear (though I'm considering picking up one of the new Bessa R3As). I've always been curious as to the handling/optical quality in the field of an M-series camera, so I wanted to give this one a spin.
What irks me a little is that my el-cheapo Canon seems to be in perfect alignment, and makes surprisingly good B&W images. It's also the quietest camera I've ever used, quieter, even, than the M6. Obviously it doesn't have worldbeater optical quality, but its 40mm lens is fast (f1.7) and it makes a pretty good street shooter with its shutter-priority exposure system.
I really need to put a roll of Provia through the M6 to do a proper evaluation. Right now it's loaded with Ilford Delta 400; when that roll is used up, I'll try the slide film.
I'm still wondering what a lack of horizonal alignment at infinity means in terms of on-the-film sharpness. We'll soon see, though.
If the RF image isn't horizontally aligned at infinity, it means the rangefinder is out of whack. Infinity is the baseline point for RF alignment; if it's off there, it'll be off everywhere else, too.
Whether or not it will affect your on-film results will depend on how you shoot with it. If you mostly shoot at longish distances at moderate to small apertures, depth of field probably will camouflage the focusing errors and you won't notice any problems. If you shoot any close-up and/or large-aperture shots, you'll probably discover that the sharpest point is something other than what you intended!
If you really want to know before you invest any important shots, you can try the traditional 'yardstick test.' Mount a yardstick on a surface that you can set at a 45-degree angle to the camera; a door works well. Put the camera a short distance away from it, such as a bit over 1 meter. Set the lens at full aperture and choose a shutter speed that will give correct exposure.
Now, focus very carefullly on the yardstick's 18-inch mark (add a strip of tape or make a bold line with a marker to make this point easier to see in the finder.) Carefully make an exposure, using a cable release to avoid camera shake. Now advance the film, defocus the lens completely by turning it to infinity, and try again. Lather, rinse, and repeat until you've used up enough of the film that you don't mind taking it out.
Now rush out and get the film processed. If you cleverly used a chromogenic b&w film, you can get it done in a few minutes at any quick-service lab. (Same with color neg film, but I find b&w negatives easier to see.)
With processed film in hand, lay it out on a lighted surface and take a good look with a strong loupe. If the 18-inch mark is within the sharpest part of the picture, all is well. If your RF is off, the sharpest part of the picture will be ahead of or behind the 18-inch mark, and you'll also know the direction and size of the error.
This is a very demanding test, and it isn't unusual for a camera that seems to shoot well to be off slightly. Only you can decide how much error you can tolerate.
PS -- A Leica's rangefinder is of very high precision, so you'll be able to see tiny misalignments that might not be visible on a Canonet, even if the Canonet isn't actually aligned any better.
PPS -- Vertical misalignments at infinity are annoying, but don't normally affect focusing accuracy. It's the horizontal alignment you need to worry about.
PPPS -- If this is only a minor misalignment and everything else is fine... well, Leica knows (and all other RF manufacturers do, too) that RFs can drift out of calibration slightly, so just about every RF camera has a concealed means of adjustment that lets a technician touch up the alignment without major disassembly.
If your camera store does NOT know that, and if you know a technician who can adjust it, you may be able to bag a good buy on that M6 by showing the seller your yardstick-test pictures and saying "Look, the rangefinder is 'way out of whack! It obviously needs hundreds of dollars' worth of delicate repair work. But it impresses the chicks, so I'll buy it if you knock down the price enough."
Hmmm...that yardstick test makes me recall the hoopla surrounding the early releases of Nikon's D70 SLR (which I own, BTW). Now I'm more intrigued than ever over what my first batch of negatives will reveal (unfortunately, it'll be Monday noon at the earliest before I can have the processed. If I'm very impatient I can run a roll of XP2 or the equivalent, but I normally rely on slide film to make appraisals about metering accuracy, sharpness, etc.
I'll be a bit peeved if a poorly aligned RF renders all or most of my exposures moot. But none of them are what I could call "critical."
Time will tell...
If you are shooting at medium distances and apertures, it will probably not show up at all. It also depends on how "out" the alignment is. The ruler test is of course a stringent test. The 90 2.8 at 2.8 and 1 meter would also be a very stringent test where misalignments might show up. Overall, unless you are shooting fast lenses wide open and at close range, you will not notice much of a difference. Since this is a rental, I would not let it bother you that much. It has surely been knocked around, which can throw them out of alignment. SLR's can be out of alignment too, only you will not notice it -- things will look in focus in the viewfinder, but then turn out not to be perfect. Again, the ruler test and a good repairman is the only way to get it perfect.
So friends, does anyone knows how to align that ultra precise RF??? Damned 2 screws I see, the same problem with infinity.
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