My Canon ae-1 and infinity mark , focus is off

[RonD]

Hello,
I have just joined and posted a thread on new members.
I have this canon Ae-1 that I purchased new in 1977.
Actually looks like new with about 30 rolls in it's life time.
I have noticed about 20 years ago that when I turn the focus ring at the infinity mark, it is slightly out of focus, from the start of infinity to even buildings 50 feet away and so forth.
I purposely focus on sides of building and the lines are slightly broken.
I do not know if it was like this when I first purchased it.
I have looked at old photographs and I cannot really notice it; but I don't know if it was before or after.
I have not used it as I afraid that it will screw up the photos.
Twenty years ago is when I had the camera sent to Toronto at a now defunct place to get the seals replaced and I had mentioned it in the letter, but, it came back the same without explanation.
My Nikon fe2 does not have this problem but, than again, it is a AD lens and goes way beyond infinity even in manual focus.
My canon also seems to be overexposing by about 2/3 when compared to the Nikon. both lenses 50mm f1.8
My canon lens is the original with the silver ring at the breech, f16 aperture limit s.c. lens.
I will take test again on a tripod with both cameras to confirm this when the weather is nice.
I think I am asking more than enough for now.
Thanks,
Ronald

 

[David Lyga]

Ronald, when you say 'out of focus' do you mean: 1) out of focus as per the viewfinder OR 2) out of focus as per the actual negative?

With SLRs that mirror's angle is CRITICAL for matching the apparent focus (VF) with actual focus (film plane). That mirror's front is resting upon a bushing so as to hold a precise angle when at rest. If the VF focus is not representing, precisely, what the film plane reveals, that mirror's angle has to be either a bit higher or a bit lower.

With the AE-1 I forgot how to adjust this angle but with some cameras (Fuji ST or Zenit) that mirror rests upon a set screw, making that adjustment easy. With some cameras, that mirror rests upon a simple protrusion of metal (Pentax K1000) which can be slightly bent either up or down.

The rule of thumb is as follows: If film plane focus is CLOSER than VF focus, lower mirror angle. If film plane focus is FURTHER than VF focus, raise mirror angle. The amount of change will be VERY small, but critical.

If you wish to explore what I said, place a very tiny piece of thin cardboard between the bottom of the mirror and the metal that it rests upon, so as to raise that mirror slightly. Then put a lens on the camera. You will be astounded with how 'inaccurate' that VF focus has become! - David Lyga

 

[RonD]

Hi David,
It is out of focus when I view the picture the photo that I wish to take.
The lines of a building are a little bit broken.
I will try the cardboard, business card between metal and mirror (assuming that I can pull it off) and report back.
Thanks,
Ronald

 

[AgX]

A mirror out of adjustment concerning its angle will yield a partially out of focus image.
Or more correct of varying degree of being out of focus.

I hinted at this already in same discussion in the past.
It can be proven by any one in short time.

 

[John Koehrer]

Before you start adjusting things, check the focus at the film plane(ground glass) If it's off there, it's
more likely that the focusing ring on the lens has slipped.

If you don't have a GG some folks have used frosted tape. With either, don't
put it on the rails, but between them.

 

[Kirks518]

Is this with every lens, or one specific lens? If it's only one lens, then it's an issue with the lens. If it's with all lenses, then it's a camera issue. Key is figuring out where it is out of focus; at the viewfinder or the film plane.

 

[RonD]

I think I will wait till tomorrow to gently look at this.
About the focusing ring..
I read on a site a few years back that adjusting the focus on a FD lens itself may require dismantling the lens and removing a piece of rubber , readjusting it and regluing it'
I have long since lost the site.
Perhaps buying the repair cdrom guides may not be a bad idea.
About my AE-1 overexposing about 2/3 of a stop more than my FE2 with the equivalent lens, are they even suppose to give me the same aperture pointing at the same place?
I do know that my FE2 meter is right on as it was checked when purchased. I will check both tomorrow with the sunny 16 soon as I can get replacement batteries for the FE2.
I do not know that there is a rule that both cameras have to meter in duo. I would think they should; but obviously I am very new at these things and finding a specific repair person in Canada?
Ronald

 

[RonD]

Kirk,
I only have one FD lens.
The (kit) lens. 50mm f1.8 s.c.
My FE2 lens is 50mm f.8 AD
Ronald

 

[MattKing]

Welcome to APUG, from the other end of the country.

For clarity, you need to determine whether your problem is just with the distance marking on the lens, or whether the camera isn't giving you well focused photographs when the image in the viewfinder is adjusted for correct focus.

You need to do a focus test, and then review the results.

 

[RonD]

I can focus well all over, it is just at infinity.
It is like it would need to turn the ring another 1/32 or 1/16 past the infinity mark to get a straight line perfectly algn.
And I do mean that they are just misaligned that I can see it, not much, even barely, but they are not perfect.
Ronald

 

[AgX]

What I do not understand is how a bought-new, nearly unused camera-kit can exhibit a focus error.

Any idea?


EDIT: yes, it was bought new back then.

 

[RonD]

My FE2 was bought new almost NOS. About 3 years ago
But I am talking about my canon AE-1 which I bought new in 1977.
Ronald

 

[Jim Jones]

A little dirt or a metal bur between the lens and its mating surface on the body can cause this problem.

 

[AgX]

Good Point.
(However then all focus settings would be off, though of course directly visible for infinity.)

Clean the female mount inside with a tissue damp with glass cleaner.

 

[SchwinnParamount]

A little dirt or a metal bur between the lens and its mating surface on the body can cause this problem.

That was exactly my problem too. Clean the surface and focus was fine.