Nikon FE2 - solutions for 1" front-focus?

[yessammassey]

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?

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.

 

[ic-racer]

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 think that should work. Though I have not 'calibrated' a SLR viewfinder to the split image. I usually use the ground glass portion, as the split image can be off slightly. But if you use the split image, then, yes, calibrate to that.

I don't have the service manual for the FE2, but on a camera like the Yashica FX-3, there are two adjustment screws. One moves the whole mirror up and down and the other affects the angle of the mirror.

 

[fstop]

Did you check to make sure there is no diopter screwed in the view finder?

Does it have the right focus screen?

Put frosted tape or ground glass over the rails and focus through view finder, then using "B" setting trip shutter and see if the image is in focus on the tape/ground glass

 

[Leigh B]

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!

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

 

[John Koehrer]

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've also never depended on focus scales for accuracy, just guestimates.
Do you have the same problem with other focal length lenses?
I have seen situations with slight shifting of the focusing rings but to have two lenses
with the same error would be very unusual.

 

[Leigh B]

BTW...
Where are you measuring that focus error from?

The defined focal distance is from the film plane to the subject.
The film plane is indicated on the top of the camera with a circle bisected with a line. The line is the film plane.

- Leigh

 

[yessammassey]

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.

That's interesting, because I did tape another FE2 focusing screen to the back of the troublesome camera. I had it resting on the inner two silver bars above and below the shutter, so... pretty much where it looks like the film rests. There was a discrepancy between focus appearing in the viewfinder and the film-plane screen. I adjusted the peg below the mirror and it looked like I had the two focusing screens agreeing with each other! Success! Or not. I ran another test roll through the camera, and this is representative of the results I got from 5 shots of the same setup, all on a tripod, refocused for each exposure:

This was focused on the '6' in the VF. Where the pencil is pointing.

So maybe adjusting the mirror isn't the way to go! Maybe shim the focusing screen? But I need to set up the focusing screen-in-the-back test again. Maybe I didn't get it properly lined up with the film plane the first time?

Here, for reference, is a similar test shot, from the same roll, with the same lens, on my FM:

The red '40' (illegible in this bad reproduction) should be in focus, where the pencil is pointing. I'd call this good enough.

Strangely, some of the photos taken with my 'good' FM were out of focus, too. There were two shots, taken with the FM, of the same wooden ruler that is featured in my first photo. They were mis-focused in a similar way as the FE2 test shots represented in the first photo. But I guess I can chalk it up to user error. (I guess... even though I used a tripod) ...None of the test shots taken with the FE2 like this have ever had the intended number in focus.

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

Sorry, I wasn't making an accurate measurement from film plane to subject. It's was just "around 3 feet".
...But, is this wrong?

Oh, and there's nothing in the eyepiece. Just bare threads. No diopter.

Finally, I apologize for the blurry digital photos of bad drugstore prints, but they get the point across, I think.

Edit:
Here's my setup for checking viewfinder focus and film focal plane agreement. Using loupe for fine focusing with the split image. I just set this back up, and it looks like my VF and the focusing screen are still in agreement. What gives? The tape isn't great (I'll be careful to clean up any residue.. left my gaffer's tape at work) but the screen is resting on the inner rails. Oh, and it's flipped the right way. Flipping it over gives wrong distances on the lens' scale when I focus.

 

[Leigh B]

...But, is this wrong?

Not "wrong", just manipulated.

Apparently they're calculating DoF based on an enlargement factor, probably to an 8x10 print.

I ran the calculation for a 4x5 film size, resulting in a 4" DoF.
When I ran it with 35mm I got the same results that you show.

That's likely a convenient normalization, but not valid in my mind.

DoF should be based on the image on the negative, not on the eventual print size.
You can print the same negative at many different sizes.

- Leigh

 

[ic-racer]

Washers under the screen need to be thicker if you can't get it correct by adjusting the mirror alone.

 

[ransel]

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.

 

[yessammassey]

So here's my follow-up post, in case someone with a similar problem ends up searching and finding this thread:

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.

Adjusting the viewfinder focusing screen as you suggest very well may have ultimately solved the issue, but the viewfinder and taped-up film plane focusing screen were in agreement (and I checked with a loupe, refocused, made sure the screen was flush with the rails, etc., multiple times), so I don't think there was a way for me to check a shim job without burning another roll of test film.

I suppose I could have 'bracketed' the shim and shot two exposures of my focus test setup for 12 progressively flatter inserts, then deveolp and see which one got the closest. But instead I liquidated the FE2 and picked up an F3 to replace it. And it's just my luck that this second auto-aperture Nikon has a serious problem, too; the shutter caps at high speeds. The right sides on many of the frames look underexposed. That's a problem I don't think I want to try and fix myself.

No more buying unrefurbished used SLRs for me anymore!

 

[RalphLambrecht]

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.