I am relatively new to Rangefinder cameras, but have had a miserable experience with my Mamiya 6 that I should share. I wrote up the issue, and the tests that isolated the problem on my Blog - http://web.mac.com/craigart
- and will copy it here:
Mamiya 6 Focus Test
When I bought the Mamiya-6 used - it is no longer being made - I ran it through a battery of tests. All of which it passed in flying colors. I knew I wouldn’t get any serious use out of it until the project was under way, so I “assumed” that a series of sharp, in focus images meant that everything was alright. I fell in love with the camera and its unique nature – I thought. Unfortunately, I neglected to test out it’s ability to focus at infinity, seemingly a no brainer for any camera. The problem with the camera came to my attention when, after three months of on-site shooting (it took that long to get the chemicals here), I began to develop my negatives - 26 rolls of which were shot with the Mamiya-6, most of those shots being tripod-shot scenics, using hyper-focusing.
To those new enough to photography to not understand hyper-focusing (or even manual focusing nowadays), hyper-focusing simply takes advantage of the fact that as one closes down to a higher f-stop (smaller aperture) more of the image both in front of and behind the focal point appears to be in focus. The standard for those hyper-focusing a scenic, using a tripod, is to set the infinity marker on the lens barrel over to one f-stop lower than the setting that one is using. So, at f22, set the infinity setting to f16 and you will experience maximum focal range (one can get more range using the same setting as the f-stop but that limits how large it can be blown up without losing what you have gained). Very simple, and you wind up with everything from about 5 feet to infinity in focus.
This system has worked for me for years, with my Mamiya 645 and the Fuji 6x7. So I didn’t hesitate to use it on the Mamiya-6. Big error. After developing a half dozen roles and finding everything beyond 30 feet drastically out of focus, I ran a series of tests.
First, to confirm my suspicions that it was the camera and not the photographer. I shot the same scene in the Mamiya as the Fuji – both at f22, hyper-focused to f16. There is a small white fence, running vertically, in the shot – very handy. The Fuji image was sharp the whole way. The Mamiya’s sharpness fell off ridiculously fast at 30 feet again. Of course, all tests were performed on tripod, with cable-release and no wind. There was a problem with the Mamiya.
I now wanted to determine if the problem was in the lens or camera - I was assuming it was the lens at this point. Bad lenses, like other unmentionables, happen. I tape-measured a distance of 7 feet from the film plane to a sign. Focusing with the range-finder I shot wide open at f3.5 with the 75mm lens. The resultant image was sharp - BUT the lens barrel read 8+ feet - very odd indeed. The same phenomenon occurred at any distance I measured, a discrepancy between measured distance and the distance indicated on the lens barrel. Normally one would assume the range-finder was off. BUT – the shot taken with the lens barrel on 7 feet instead of focusing, created an image of the sign very out of focus. Range-finder was right, lens was wrong. And, at all distances, the discrepancy was the same amount of turn of the focusing ring.
Now I was intrigued. I set up the same distance test that I had used for the Mamiya vs Fuji. The first shot, at f3.5 with the lens set at infinity was blurred at infinity and throughout most of the image. However, there was a line of razor sharp rocks at about 30 feet from the camera! Wow, I was beginning to understand. The second shot, f22 with lens set at infinity was SHARP all the way to infinity - finally. But, then when hyper-focused to f22, f16 and f11 all images were still blurred beyond 30 feet. The first one to start coming into focus was hyper-focusing at f8. F5.6 was best and most like f16 should have been. Eureka.
On my Mamiya lens, hyper-focusing the spin of the lens barrel from f22 to f8 equals the spin from 8+ feet to 7 feet equals the spin from infinity to 30 feet. Focusing naturally moves the innards of the lens away from or closer to the film plane. Needless to say, either the lens was grossly defective (not likely), or the camera body - which has a collapsable lens mount - is grossly maladjusted. I then ran the same tests on the 50mm wide angle and the 150 telephoto lenses. Both of these yielded results actually worse than the 75mm lens. The range-finder focusing continued to compensate for serious lens-barrel anomalies at distances short of infinity. But, hyper-focusing at f22 didn’t bring in sharp images at any setting, on either lens. Yet, with infinity set for no hyper-focusing, I essentially got hyper-focused images.
The kicker, proving to me beyond a shadow of a doubt that the problem is in some almost unimaginable adjustment to the collapsable lens mount, is that foreground sharpness tests at f22 and hyper-focusing - again in comparison tests with the Fuji - showed that while objects blurred past 30 feet, objects much closer than should have been were in focus. THE FOCAL POINT IS OFF. THE LENS MOUNT MUST BE HOLDING THE LENS A SMIDGEN FARTHER FORWARD THAN APPROPRIATE. Does it seem even conceivable that there is an adjustment that can be made, even at a repair center for this – I couldn’t imagine it at first. But then I remembered reading that the range-finder can become inaccurate and need resetting at a repair center. Hmm. What if the range-finder and collapsable lens mount were linked to the degree that what gets out of alignment is actually the lens mount, which controls the focusing alignment? What a particularly precious bit of engineering that would be, leaving anyone looking at the lens barrel up a creek without a paddle, as the lens mount roams all over creation and the focusing mechanism keeps up with it. All the literature states is that the range-finder can be off, not that the whole damn lens mount gets unset, rendering the camera next to useless for some purposes. The camera provides no clues if you keep using it in focus mode, or don’t shoot at infinity with the lens wide open. The range-finder compensates, as long as there is enough lens barrel turn to allow for it. Whoop-dee-freeking-do … John Belushi
So, I sit here with 26 rolls of useless work, three months of work with the Mamiya-6. If I wasn’t using the Fuji for some work, I would have zero, zip, nada, nuttin’ to show for all that effort. I will defer any attempts at repair until we get home. In the meantime, I at least now know how to compensate for the problem – if I have to.