- Joined
- Dec 19, 2015
- Messages
- 145
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Can I place that over the film plane, lock up the mirror, and focus the lens using the split image, then compare it to the prisim view and make adjustments until the two agree?
I'm trying to understand how you determined a 1" focusing error at 3 feet.I've got this lovely 50 1.4 ai-s lens, and am missing out on the otherwise quick and accurate focusing I could be achieving with the bright viewfinder image that the wide aperture affords. Sad!
Either of the above will work. You can use just about anything to magnify the image
on the surface you choose at the film plane.
I don't believe I've ever come across a camera where I've had to fool with mirror position
for focus problems.
I'm trying to understand how you determined a 1" focusing error at 3 feet.
The DoF of that lens wide open is 4 inches at 3 feet.
- Leigh
Not "wrong", just manipulated....But, is this wrong?
Try shimming the focus screen. My first Canon Digital Rebel (300D) had the same problem. It did fine when auto-focusing but if I manual focused with my 50mm f/1.8 at wide open, I always missed focus - always! I removed the focus screen and it had a brass shim spacer under it. I took fine (400 grit) sandpaper and polished it, reinstalling it after every couple minutes of work on it, doing a couple test shots on a ruler like you are doing, until I finally got it to the exact thickness I needed. The problem was solved.
It has been years since I did that so I don't know which way you need to go but I think my camera was focusing in front of the point I had focused on, like yours.
FE2 user here. I was noticing missed focus with two different fast 50mm lenses, so I did a tape measure test, and sure enough, at about 3 feet, actual film-plane focus is almost exactly 1 inch closer than where focus is apparently placed when using the split image viewfinder.
I replaced the focusing screen and shot another test roll. Same issue. I tried adjusting ever so slightly the reflex mirror's resting angle. Still front focusing, although now maybe a little more than before...
This is wearing out my patience, and the people at my local lab are probably starting to think I have an obsession with blurry cat pictures and rulers. I'd much rather put a couple hundred dollars toward more lenses and film rather than another EX condition camera body.
Any tricks I can try to fix this? I still have the old focusing screen. Can I place that over the film plane, lock up the mirror, and focus the lens using the split image, then compare it to the prisim view and make adjustments until the two agree? Or does the thickness of the screen prevent it from being useful in that way?
There's a small bar that sticks out from the right side of the mirror box. It can be rotated to adjust the angle that the mirror normally sits at. If I have a 1.25in front focus at 3ft, is there any way I could figure out exactly how much to rotate the bar to get back to correct focus accuracy? Or maybe an angle for the mirror?
whenever things are made adjustable;they have to be adjusted wonder why that is
I've got this lovely 50 1.4 ai-s lens, and am missing out on the otherwise quick and accurate focusing I could be achieving with the bright viewfinder image that the wide aperture affords. Sad!
At least i still have my backup FM. It doesn't have a replaceable focusing screen, so it's probably less likely to have focus accuracy problems... Right? I'm kind of afraid to test it out at this point.
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