Checking Focus for Film SLRs


pwnies5600

Member
Oct 29, 2014
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Clementi
Hi all sifu,

After a month of shooting, I'm back with another question. This time, I'm having some issues with focusing.

I have been shooting on a Nikon FE and I just got the first roll developed and scanned. For some reason, 90% of all my photos focused closer than 5m or so have been pretty out of focus. I'm certain that while shooting the focus looked fine in the split prism finder, but somehow that didn't quite translate to the film plane.

Therefore, I would like to know what the possible reasons for this might be. I've read online from various sources to check if the focusing screen is positioned right. I've removed the screen and set it back into the bracket. That made about 0.10m difference at 0.55m point of focus. Other sources have pointed to misaligned mirrors but I have not found the mirror to be loose. What are some of the more likely reasons for such a phenomenon?

Another question I'd like to ask is how can I check the focus at the film plane. I'd like to do this so I can compare the focus in the viewfinder and at the film plane. I have yet to find any concrete methods to do this so any suggestion is welcome!

Some photos have been attached for reference. This doesn't seem to affect objects at infinity but for closer focus distances the effect is apparent. Shooting stopped down helps but it's still not quite as sharp. On a related note, this was shot on expired Ultramax 400 that I undercompensated the loss in sensitivity for so most shots came out underexposed. Focus is usually set at the center of the frame.

Thanks in advance for your help and kind attention!

Edit: Forgot to mention, lens is a 50mm f1.4 AI

Edit 2: I'm also using a +1 diopter eyepiece for the F3 on the finder (even though I don't need the diopter adjustment) to keep the dust out of the finder.

Photos here, unable to attach due size restrictions on forums. Sorry!
 

Before questioning the 'intestines' of the camera, I would keep it simple and check the usual things.
1) Remove the diopter eyepiece. Using +1 corrects for people who needs reading glasses (on short distances) - and that where you observe the issue.
2) Use a cheap, film a tripod and a focus test chart to verify the focus in viewfinder / split prism and on image
3) Get another lens for cross-checks.
4) Check whether the are any shims required for the focusing screen you are using. If the focus screen is not the original one, chances are that shims are either missing or are required.
 

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Before questioning the 'intestines' of the camera, I would keep it simple and check the usual things.
1) Remove the diopter eyepiece. Using +1 corrects for people who needs reading glasses (on short distances) - and that where you observe the issue.
2) Use a cheap, film a tripod and a focus test chart to verify the focus in viewfinder / split prism and on image
3) Get another lens for cross-checks.
4) Check whether the are any shims required for the focusing screen you are using. If the focus screen is not the original one, chances are that shims are either missing or are required.

1) Removed.
2) Will do. I can use a ruler for that if I don't have a focusing chart right?
3) Aight will borrow from a friend to do it. Don't have any lenses myself save for the one that came with it.
4) How do I tell if the screen is original? I don't see any shims but I'll give that a go with making some when I have the time.

Thanks

Edit: I just remembered that 3 is unlikely as I shot with a friend's 28mm f3.5 AIS as well. The photos shot on the lens also exhibited the same issue but to a lesser extent. Perhaps it is the greater depth of field and shorter focal length that negated some of the effect?
 

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1) Don't forget using your glassed in 2) - it's done on minimum focus distance.
2) Google for focus test chart, print the pdf. The center mark is more dominant.
3) Yes, the greater depth of field in wide angle will 'cover up' focus issues.
4) Can't help here. Either check online for replacement tutorials to see whether any shims are mentioned. Also, there should be online resources stating how the camera was originally equipped when sold. Models of specific years might have different features.
Alternatively, a good repair shop could help here with a second unit for comparison.
 

A jury rigged check will be to find a matt material (eg. translucent whitish plastic/glass ), open the camera back, paste the matt material on the back where the film is supposed to be (camera side, not rear plate side).
You can then check the image that is formed from lens to matt screen.
Check this wrt focus on the view finder and image formed on matt screen.

You will have to know how to shim your focus screen to calibrate it, if its out.
 

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Thanks for the suggestions. I'll try it out in the next few days. In the meantime I talked to one of my other friends who shoots film more frequently and he suggested that it could be because the pressure plate isn't pushing the film against the rails. At least, that's what was derived from some of the images having a tilted focal plane where the only one of the edges is in focus, as well as this small nick on the pressure plate (see the two pictures below) that he thinks is caused by the film guide. The pressure plate is sitting on the film guide and not on the rails like on my Spotmatic so it's not pushing the film against the rails.

What are your thoughts? Could this be a plausible explanation for the symptoms as well?

Images here:
 

I'm no expert but I don't think pressure plate is the issue of course you can check visually if it is slanted or not. Basically this is an alignment issue
so first thing to check is to look into viewfinder if the 4 corners are sharp or not (with lens and focusing).This type of adjustment is not trivial so it's best
to download FE service manual and see what are the possibilities and what you are up against.It could be mirror or prism box but do have a thorough
reading and looking at the exploded diagrams. Prepare a suitable surface to work on preferably with a cloth underneath to catch tiny parts from rolling off.
Have an system of disassembly and storage of parts.Good luck.
 

Tried out @Octarine and @pinholecam suggestions today. Seems that the results suggest focusing screen is misaligned after all. The focus is off by quite abit near minimum focusing, I'll do another test during the daytime tomorrow at a longer focusing distance just to confirm.

I also managed to ask a friend to help me test my lens. The lens focuses fine on his FM and gives sharp images.

Images (test results) here:
(If the red lines are aligned, that's film plane in focus. Position as shown in the image is viewfinder focus.)
 

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I'm no expert but I don't think pressure plate is the issue of course you can check visually if it is slanted or not. Basically this is an alignment issue
so first thing to check is to look into viewfinder if the 4 corners are sharp or not (with lens and focusing).This type of adjustment is not trivial so it's best
to download FE service manual and see what are the possibilities and what you are up against.It could be mirror or prism box but do have a thorough
reading and looking at the exploded diagrams. Prepare a suitable surface to work on preferably with a cloth underneath to catch tiny parts from rolling off.
Have an system of disassembly and storage of parts.Good luck.

Visually, it is somewhat slanted. I'm still not quite sure how it sits when the door is closed though. Will update again on this. I'll try to find a manual and give it a read. Thanks!


Edit / Update: I just read the repair manual (page 39) and I've made a shocking discovery that the film pressure plate is indeed installed the wrong way. The plate is supposed to sit closer to the rollers on the right (see image 2 below). I'll rectify it in the coming days.


Edit / Update 2: I did it. Now the plate no longer collides with the guide and is able to fit flush with the rails. Still have to calibrate the focusing screen though.

 

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Minor update: I've been studying the repair manual for the past few days. I can't just shim the focusing screen because the issue is front focusing so I'll have to open the camera up. Seems like it's going to take some elbow grease to get to the bracket that's holding up the screen. In the meantime I got another FE, hopefully this one doesn't have the same issue so I can use as reference. Fingers crossed.
 

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I haven't gone out to shoot with my second FE yet but I will next week. However, I did realise recently that the second FE has this problem where the film advance lever doesn't stop winding forward once the shutter is cocked. I took it apart and was surprised to find that my original FE looks different from my second FE, presumably missing some parts (but yet still seemingly more mechanically sound than the second one). Anyways, more to come. I'll update as things go along :)

*The second FE I got is the bottom one.
 

I'm happy to report that despite the non-locking film advance mechanism and a slightly hazy viewfinder, the second FE performs flawlessly!


I guess all there is left for me to do is to figure out why it can't lock before I disassemble the top plate to figure out how to adjust viewfinder focus.
 

I haven't gone out to shoot with my second FE yet but I will next week. However, I did realise recently that the second FE has this problem where the film advance lever doesn't stop winding forward once the shutter is cocked. I took it apart and was surprised to find that my original FE looks different from my second FE, presumably missing some parts (but yet still seemingly more mechanically sound than the second one). Anyways, more to come. I'll update as things go along :)

*The second FE I got is the bottom one.


As far as I can tell the 2nd. FE is a modified production. You can see from service manual the brass 3 tab screw plate is the same shape (sectioned in red)as the first Nikonj FE. I don't think there are missing parts.

nikon FE bottom.JPG
 

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As far as I can tell the 2nd. FE is a modified production. You can see from service manual the brass 3 tab screw plate is the same shape (sectioned in red)as the first Nikonj FE. I don't think there are missing parts.

View attachment 38765

Hmm seems you are right. Today I managed to remove a part of the mechanism on the (chrome) second FE. It's not shown in the service manual though, but on this forum here it is suggested that it is this part that is causing it to advance continuously.


The thread lock was really strong on the screw holding this bit in, took me a while to get it off. Anyways, I'll take it to a workshop with a bench vice to see if I can bend it back. Will update.
 

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Update: bent it back 90 degrees. Now it is not as easy to continuously advance. Of course with enough force it will still happen, but I'm happy with it as is. Next up, actually fixing what's in the title of this thread :p
 

Update:

Anyhoo, I'd like to give this old thread some closure. I finally got around to shooting the original FE with the focusing issue. Turns out the problem really was the uneven film pressure plate in the reply quoted below. After the film pressure plate was installed correctly the camera works flawlessly.

That being said, I did manage to disassemble the FE up till the focusing screen. Turns out there's really nothing you can adjust down under the prism so that was a bust.

However, in the process of fixing the first FE I have bought another five (5!) more FEs, each with varying issues to be repaired. Guess I'll be busy for a while XD

Enjoy these frames from the test roll!
 

I think this thread will be the first exhibit in the (financial & time) health warning that people have to sign before starting on film cameras as a new hobby. Been there, done that
 

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Film cameras are just fine. The member happened to buy a FE in which a careless or ignorant person had tampered with the camera and re-installed the pressure plate wrongly. The slanted pressure plate is obvious to any casual observer. Some of us used film cameras long before digital cameras.
I just met a China tourist using a Konica Hexar body fitted with a collapsible vintage chrome Leica lens. Probably a 50mm F2 Summicron.