Canon F-1N: No infinity focus

[Tony-S]

I just received an EX grade Canon F-1N from KEH and it does not focus to infinity. I have reseated the focusing screen (PE, split-image/microprism) and the problem persists. For example, when my 24mm f/2 is set to infinity, it focuses at about 10 feet. With my 50mm f/1.4 the problem isn't as bad, but it, too, is not reaching infinity. Both lenses work fine on my A-1. Any ideas? I hate to return it but will if I need to. A bit frustrated with KEH recently - I had to send two copies of the 35-105 f/3.5 back because of different problems.

 

[frobozz]

That's downright bizarre. I'm not even sure I can figure out how that can happen?! Assuming the screen and prism are installed properly... Is the mirror not returning all the way down? (I still don't think that would cause this.) Any evidence that the lens mount has been messed with?

Duncan

 

[Markster]

It has to either be the prism in the viewfinder not being seated properly, or possibly a major problem with the mounting bracket for the lens itself.

I don't see how the problem wouldn't be rather obvious, though. If it were a mount problem you'd be able to see some issue before putting the lense on, and the viewfinder only fits on one way if I recall.

It's rather strange.

 

[gone]

I'm not sure how your camera is set up, but I have a F-1, 2nd version, and it's possible to put the prism housing on wrong and not have it fully seated. I would make sure it's all the way down on the camera. If that isn't the problem, and you see nothing wrong w/ the mirror/lens mount, I would send it back. I buy from KEH a lot, and usually have good luck, but they aren't perfect. The good thing is that they will take a return. Aren't their cameras warrantied for 6 months? You could always send it back to them to be repaired.

 

[David A. Goldfarb]

If you have the New F-1 (sometimes called the "F-1N" not to be confused with the second version, the "F-1n") then it sounds like you may have the focusing screen upside down. I didn't know that it was possible to install it upside down, and I'm not about to try it on mine, but the matte/grooved side should be down with the black edge under the tab at the front of the camera and the chrome edge on top toward the back of the camera.

If that's not it, it's something like a mirror alignment problem. Make sure there's nothing obviously preventing the mirror to return to the normal viewing position.

 

[Yeeski]

It has to be either (a) the focusing screen is defective or isn't properly installed, or (b) the mirror is out of adjustment. It can't be the fault of the viewfinder since it only re-orients the image from the focusing screen. With a basic (i.e., non-magnifying) waist level finder, you are essentially removing the prism viewfinder and focusing directly off the focusing screen. The waist level finder is nothing more than a hood to block stray light. Check to see if your mirror is all the way down and seated.

 

[ic-racer]

This:

 

[John Koehrer]

Ever seen a broken body casting? It was held together by the top & bottom covers.

 

[clayne]

Ever seen a broken body casting? It was held together by the top & bottom covers.

Seems pretty unlikely with an F-1!

 

[Andrew K]

This:
View attachment 74444

Try this - if it doesn't work then the spring on the inside of the mirror box is broken (it's happened to one of mine).

Sorry to say it's a MASSIVE job and not worth doing, but you can file the stop down to adjust infinity focus (again what had to be done to mine).

Its a job I wouldn't tackle, and I used to fix then when I was a camera tech at Canon in the 90's!

 

[Charles Wass]

If the mirror is seriously misaligned I would expect that the viewfinder image would show some vignetting at top or bottom, though I believe the viewfinder coverage is not 100%. If the camera is the F-1n (not New F-1, AKA F-1N) then the meter will not work with the screen upside down. I have looked at both cameras and it seems it might be possible to install the screen upside down.

 

[Tony-S]

The focusing screen is in correctly and mirror is returning, so it must be an alignment issue. Time to send it back to KEH for a replacement. I really wonder how much QC testing KEH does. I've been using them for years and until recently have not had problems.

Thanks to all - I appreciate your guidance.

 

[Tony-S]

Well, the replacement camera arrived today and seems to be in good working condition. However, one of the screw-in bottom covers is missing. I have an email to KEH requesting they send me a cover, but I'll report back here if for nothing else but to show how KEH responds.

 

[elekm]

The angle of the mirror has to be out only a fraction of a millimeter for a camera to not focus correctly at infinity. And some cameras are easier than others in making this adjustment.

I had the same problem with a Yashica Contax 139 Quartz. On that camera, you have to remove the front body panel and turn a small screw to adjust the angle of the mirror.

On a Zeiss Ikon Contaflex I (and other cameras), you remove a cap on the base of the mirror box and turn a small post.

 

[Tony-S]

The angle of the mirror has to be out only a fraction of a millimeter for a camera to not focus correctly at infinity.

In case you missed it, I returned the defective camera for a replacement. It seems to work perfectly fine. It's just missing one of the bottom covers.

 

[David A. Goldfarb]

If you search on eBay, you can usually find sets of the three bottom caps at a not unreasonable price.

 

[dynachrome]

I have a Nikon F2 body which will not allow correct infinity focusing. For now I'm not doing anything with it because I have other F2s. Eventually I might send it to Sover Wong. If he can't fix it, I don't know who could.

 

[Jon Goodman]

Mike Elek is correct in telling you that only a small difference in mirror adjustment will wreck the focusing ability of a camera. If you know your focus screen is installed correctly (not upside down or cocked in the frame), then I'd look at the focus screen first.
Jon

 

[Jackthompson1998]

Hopefully some across this in future, I found the solution. I had the exact same issue with mine. I adjusted this little screw which changes the placement in the mirror, see picture below and solved the problem. To do it properly you would need to disassemble the whole camera, however I managed to do it with my girlfriends very thin and strong tweasers. (She wanted to murder me afterwards because apparently they were expensive and I blunted the ends by using them on metal, lol)
Anyway if you are adjusting them, if your camera focuses passed infinity, then you need to adjust this screw clockwise, however if you find your camera does not focus to infinity, then you need to twist it counterclockwise. Do not adjust it much as a small turn makes a huge difference. Also be aware that if you do chip of bits of the screw or the tweasers to clean them out before you action the camera as debris could damage the shutter ect. Also I tried turning it with pliers first to no success, you do not need much force to twist it but the tool you use must be very slim to fit between the screw and the side to manage to twist it.

 

[dynachrome]

I have more Canon New F-1 cameras than Carter's got liver pills. On many SLR cameras the screw used to adjust the mirror angle is covered in some kind of varnish to keep it from moving. Luckily, all of my New F-1cameras as well as my F-1 and F-1n cameras have correct infinity focus. I was told by a repairman some time ago that the New F-1 does not have a simple mirror angle adjustment like some other cameras. Another problem with some SLRs is that the glue holding the mirror in place starts to get loose and the mirror drifts downward. This can cause the image in the bottom of the finder to be blacked out. The F-1s are some of my favorite cameras. Enjoy yours.