don

This is a normal condition, when the batteries are getting weak. Nothing wrong with the camera.

The 17-35afs is particularly known for this. Nikon has replaced my autofocus motor TWICE for this problem. The second time, they had the nerve to say I had damaged it, and forced me to pay $450. This is a known problem on the 17-35. I haven't seen it on any other afs lenses.

I use the 500/4P plus 1.4x and 2x converters. The technique problems you will wrestle with are not because of mirror lockup. The whole assembly itself is quite long and heavy. It will overwhelm any tripod head, including the Arca. I now use the Kirk King Cobra head, which works nicely, but still with the whole thing balancing by the lens tripod foot, there is some vibration. You have to use good long lens technique, which in this case means keeping your hand holding steady weight on the top of the lens, to damp out vibrations.

 

MLU is simply not the biggest problem you will need to worry about.

Adam: I have no experience with the Contax 645, but I would submit that your application is *exactly* what rangefinder medium format cameras such as the Mamya-6 and Mamiya-7 were made for. I can put my Mamiya-6 with 50mm, 75mm, and 150mm, all in a very small waist pack. Reliability problems are simply non-existent. If you go that route, be sure you get used to rangefinder focusing before your trip.

This is my test procedure:

 

Set up the camera on a tripod, about 8 feet from the subject. The exact distance isn't critical, but should be near (not at) the minimum focus distance.

 

Use a 3-dimensional subject, with some defining surface. We have a candleholder which has several candles in a row. I set it up so that the row of candles is *not* parallel to the film plane. I set it up so that the row of candles is at a slight angle.

 

Using the rangefinder, focus on the middle candle. Note you can only focus from near-to-far. If you focus from far-to-near (or by back-and-forth), you will not get an accurate focus.

 

Take several pictures, with the lens at wide open aperture. Refocus between each shot.

 

When you examine the results, the middle candle (or whatever you use) should be in correct focus. If it is not, you will be able to see which candle is in focus, and know if the rangefinder is in error on the far-side, or the near-side.

 

Do this with all your lenses. Assuming you have 3 or more lenses, this will tell you if the problem is the camera, or the lens. It can be either, although the camera adjustment is more common. I did have a Mamiya-6 lens that had a problem with the lens. If you only do the test with one or two lenses, you won't know which item is out of adjustment.

""The M6 meter is an averagiong meter. It looks at the entire viewfinder area, even what's out of the picture"

 

That information is not correct. The M6 meter is similar to the M7. You are correct that the angle of view of the meter does not change when you change lenses. The meter reads a fixed angle. With the wider lenses mounted, it *approximates* the area of the rangefinder patch. With the 150mm lens mounted, it *approximates* the full frame.

 

The angle of view of the meter is the same for both the M6 and M7, but since the M7 has a wider film format (and therefore a wider angle of view in the viewfinder), it would seem to the user that the meter was more selective. It is reading the same angle, but that angle is a smaller portion of the viewing area. I suspect that is the difference that the original poster has noticed.

 

Very early M6's (only the first few months made) were very susceptible to stray side light, affecting the meter. Later M6, all M6MF's, and all M7's have a baffle surrounding the meter cell, which greatly reduces that problem.