D200 backfocusing problem

[willie_901]

The split-screen indicates focus by aligning a vertical surface in your subject by manually turning the focus collar. The single split screen circle is located in the center of the frame. You have to focus and reframe if you focus on an off-center object manually with the Katz-Eye.

AF and manual focus are completely independent. You can use the AF lock indicator for off center focusing. You can use AF with AF lenses as if the Katz-Eye was not present. The split circle is just a supplemental way (more reliable) to focus manually. One advantage of the Katz-Eye is it will let you figure out how to best use the AF lock light to manually focus a given lens. The Katz-Eye and AF light will both achieve focus at the same point (if your AF system is working properly)

On my D200 the AF areas remain visible and still work with the Katz-Eye screen installed. So you would know which focus point is active as soon as you activated the AF circuit. You can select the active point as before.

 

[jonmanjiro]

The split-screen indicates focus by aligning a vertical surface in your subject by manually turning the focus collar. The single split screen circle is located in the center of the frame. You have to focus and reframe if you focus on an off-center object manually with the Katz-Eye.

AF and manual focus are completely independent. You can use the AF lock indicator for off center focusing. You can use AF with AF lenses as if the Katz-Eye was not present. The split circle is just a supplemental way (more reliable) to focus manually. One advantage of the Katz-Eye is it will let you figure out how to best use the AF lock light to manually focus a given lens. The Katz-Eye and AF light will both achieve focus at the same point (if your AF system is working properly)

On my D200 the AF areas remain visible and still work with the Katz-Eye screen installed. So you would know which focus point is active as soon as you activated the AF circuit. You can select the active point as before.

this is a much better description than mine 🙂

i would only add that the AF sensors are not actually part of the focus screen though it looks that way through the finder.

 

[Oscar Levant]

My D700 is dead-on accurate with manual focussing. The focus dot is very accurate.

My D200 and D1, now gone, were also accurate with AI manual lenses.

 

[willie_901]

Oscar,

I'm not surprised. My D300 is much better than my D200(s). I felt a Katz-Eye was required for the D200 but I never bought one for the D300 because the D300 focus dot is so reliable.

 

[Rob-F]

The mirror can be out of position, and that will cause problems. Just like when a rangefinder is out of calibration. I find it easier to calibrate the rangefinder when there is a problem.

As far as Nikon's AF-Confirm, it works well on my 10 year old E3 and 8 year old D1 DSLR's. And it works well on my N8008s. Have the camera checked.

I did finally manage to lift the mirror, but taking a good look around, I saw nothing that looked like an adjustment for the mirror position. I saw two short thin rods sticking out the side that looked like they might be limit stops for setting the mirror position. But I didn't notice anything that seemed like an adjusting screw. There is definitely a difference in the focus I get with the screen, vs. the point of sharpest focus as determined by trial and error focusing.

Does anyone know of a DIY way to tweak the mirror position?

 

[jonmanjiro]

I did finally manage to lift the mirror, but taking a good look around, I saw nothing that looked like an adjustment for the mirror position. I saw two short thin rods sticking out the side that looked like they might be limit stops for setting the mirror position. But I didn't notice anything that seemed like an adjusting screw. There is definitely a difference in the focus I get with the screen, vs. the point of sharpest focus as determined by trial and error focusing.

Does anyone know of a DIY way to tweak the mirror position?

Rob-F, despite others giving advice to do so, I strongly recommend that you DO NOT try and adjust the mirror in any way. You'll either end up damaging something or putting the mirror out of alignment.

Your problem is that on your D200, the distance from the lens mount to the focus screen should be the same as the lens mount to the sensor plane (46.50mm) but is slightly longer (i.e. backfocusing). What you need to do is install an extra shim inbetween the focus screen and the focus screen base to bring the focus screen closer to the mirror and shorten the lens mount to focus screen distance.

This was a known problem on some D200 cameras! If you PM me your email address, I will email you the instructions for installing the Katzeye focus screen. These instructions show how to remove and reinstall the D200 focus screen and show where the shims are installed. With this knowledge you should be able to make and install an extra DIY shim.

Jon

 

[willie_901]

Jon gave you very good advice.

 

[Rob-F]

I got it, Jon, thanks! I'll do it tomorrow when I'm fresh, and I'll see how thick the shims are. I'm sure I'll find something around here to make one out of. I never throw anything away! I'll probably wind up buying a Katz Eye, too. I really don't think I want to give up the D200 for an M8, R-D1, etc. as the Nikon is really more versatile.

Thanks again!

Best, Rob

 

[Rob-F]

A progress Report:

Actually it is the focus conformation dot that is back-focusing. When focusing with the screen, I found I was front-focusing. Finding two shims behind the screen, I checked them with my old Brown & Sharpe micrometer. One shim measured .0076; the other was .006. I took out the thinned one. The focus was much improved. I'm thinking of substituting the .006 one for the one that's in there now, just to see if it's any better. But it looks so good as it is, I may just shoot with it for a while before I try that experiement.

Thanks to all, especially to Jon!

 

[willie_901]

Thanks for the update.