Newbie - my 135mm RF lens doesn't focus to infinity

[cosmicpop]

Hi there

I hope I'm posting in the right forum. Forgive me if you don't appreciate these kinds of posts around here 🙂

I recently bought a 1953 135mm f/3.5 Canon RF lens from eBay, and I'm using it with a Sony NEX5. I'm using an M39 to Sony E-mount adaptor from a reputable company.

So far I've had excellent results, the lens is very sharp. However it doesn't focus further than about 50m away. The lens needs to turn another millimetre or two for infinity focus to be achieved. The distance markings on the barrel line up as expected.

Do you know if the infinity focus of the lens is adjustable in any way? There are a few very small screws on the outside of the barrel. Do these screws allow for adjustment of the lens or are they for another purpose entirely?

Thanks for your help!

James

 

[peterm1]

Ifound this is not an uncommon problem with longer Canon screw lenses when used with an adapter on another camera (although I was using mine with a Leica M camera / adapter). I have also had similar problems with chrome 135mm (both f3.5 and Serenar f4 versions) and the chrome 85mm f.18 (or is it 1.9 ? - I cannot recall). (Funny enough I never had this problem with any black and chrome Canon lens and still own a 135mm of that sort, that I occasionally use with my Leica M8 and an external finder.)

In my case this meant that the lens was not properly focussed at any intermediate distance as well as at infinity. (Probably because I was using mine on a Leica M. You may not have this issue with the NEX at all distances is it is not reliant upon a mechanical rangefinder cam which works off the helix at the back of the lens as with the Leica.)

It is possible to have this corrected by a competent repairman but I resold mine so have not had it done. The main issue is where and how much to adjust. My camera guy said I should find a picket fence and pick / mark a focus point at various intermediate distances then focus on these each in turn, firstly by using my eyeball then by using the lens scale focs marks. Do this for each of two or three intermediate points (and infinity) He could then use this info to make the necessary adjustments. I do recall that I did experiment myself with some of the screws you mention but never got it right as I was only fiddling.

I have no firm idea why this problem can afflict Canon long lenses but it suggests that Canon's camming arrangements are a bit different from Leicas. (As i say in your case the reason is slightly different.)

 

[cosmicpop]

Thanks for the reply.

As I say, this lens is unable to focus on *anything* past around the 50m mark. I suppose I'll just have to not take photographs of anything further that 50m away, but that's a bit of a bind.

Thanks!
James

 

[stupid leica]

to get you by, you could just stop the lens down. It will work in many situations.