Canon 55f/1.2 focus

[christopher_ward2]

<p>I am frustrated with my Canon 55 f/1.2 FD #217xx. The lens has been checked for infinity focus ,but seems not to focus to infinity with my cameras (A-1 ,T-70 ,AE-1). The split rangefinder is off. The tech finally tweaked the mirror rest on the T-70. Could this be a worn out mount flange on the lens? The lens seems to mount snug on all bodies. My Nikon 55 f/1.2 seems to focus to infinity on all my Nikon bodies. Odd lemon lens or quirky f/1.2 lens? Chunky doorstop? Any similar experience out there?<br>

Chris</p>

[matthijs_velsink]

<p>It is unlikely that a worn out lens mount is causing the issue, because that would put the lens closer to the film, resulting in the ability to focus <em>past</em> infinity. Can the focusing mark even reach the infinity mark on the barrel? If not, there is probably something blocking the focusing mechanism. If it can, then there must be something wrong with a lens element.<br>

BTW, isn't it focusing <em>past</em> infinity? Lenses can often focus beyond infinity, in order to compensate for lens expansion due to heat. Almost all of my MF lenses can. I sometimes think I can't reach infinity, just to discover that I'm already <em>beyond</em> infinity.<br>

Please don't use it as a doorstop, you can always send it to me :)<br>

Matthijs</p>

[christopher_ward2]

<p>The 55 f/1.2 does not focus past infinity. It will not focus to infinity. When I frame a building at any distance the split image rangefinder on the focus screen will not line up. This happens on all three of my Canon bodies. Makes me crazy when the tech says the lens is fine on his machine. One body maybe ,but all three! No dents or signs of abuse or unusual wear that I can see. Maybe the lens knows I'm a Nikon guy!<br>

Chris</p>

[SCL]

<p>It sounds like another tech might more fully examine the various options for you. Have you tried self collimating it just as a double check. Here's a link to a site which has photos of the setup to do the test http://elekm.net/zeiss-ikon/repair/collimate/</p>

[john_shriver]

<p>All you collimate on an SLR lens is the infinity stop, or infinity shim, depending on the lens design. (Topcon used selected shims, as did Canon rangefinder lenses. Pentax uses an adjustable stop. No idea what Canon SLR lenses use.) Any wear on the lens mount (camera or lens) would cause a lens to focus past infinity.<br>

The accuracy of focusing (what is in focus on the screen is in focus on the film) depends on the distance from the lens mount to the film and focusing screen being the same. Generally rough adjustments are done with shims on the focusing screen, and fine adjustment by adjusting the tilt of the mirror.</p>

 

[rdm]

<p><a href="../photodb/user?user_id=6341239">Matthijs Velsink</a> Asked you a great question but you didn't answer it .<br /> You really should Look at the lens and see if the focusing mark shows it even reaching the infinity mark on the barrel. Forget bout what you see in the viewfinder. Maybe the internal helicoid is snagged up someplace.<br /> That is something that happened to a 128mm lens of mine, tho it was worse after a cleaning and the tech needed to re-adjust it.</p>

[christopher_ward2]

<p>The barrel of the lens stops at infinity. The barrel moves smoothly. The screw heads seem undamaged so a home repair attempt that failed is unlikely. Maybe a flipped element or lens group from a bad CLA? It is closer to the thrift store donation box each time I mess with it.<br>

Chris</p>

[gordon_yee]

<p>The critical issue is the infinity focus of your lens, not what you see in the viewfinder. Have you taken pictures with the lens and your cameras to determine if the lens is, or is not, focusing to infinity? If the actual images it creates are in focus at infinity, your lens is fine. The problem may be that the split-image rangefinders are not optimized for large apertures, in which case you should focus with the micrprism ring and/or the matte portion of the focusing screen.</p>

<p>It's highly unlikely that wear in the lens mount has caused a shift in focus. This type of wear is nearly impossible in normal use with respect to Canon's breech lock design.</p>

[matthijs_velsink]

<p>I also thought about a bad CLA, Christopher. But wouldn't a flipped/shifted lens element result in a soft lens at all focusing distances? Because your lens does focus well at closer distances, right?<br>

Gordon might have a point there.</p>

[Gus Lazzari]

<blockquote>

<p>"seems not to focus to infinity with my cameras (A-1 ,T-70 ,AE-1)"</p>

</blockquote>

<p>Then why would you alter the T70? It isn't logical to have three separate units off; it's the lens!<br /> <br /><br /> Gordon is correct. <br /> Since breach lock lenses "kiss" two tubes together without any rubbing, no wear can occur.</p>

[rick_janes]

About a month ago I looked at a Canon R (Canonflex era) 58/1.2 with serious focusing issues, perhaps there are some

shared problems?

 

To start with, the focusing ring would stop several degrees short of infinity with the lens attached to a body (or the

breech lock ring in its mounted position). Removed from the body, it behaved more normally but the travel stop was

not hard and mechanical as you'd expect- it was a more mushy feeling.

 

Even stranger, infinity focus was possible through the viewfinder...with plenty of focusing ring rotation left beyond it!

 

I suspect that poor lens received some extremely poor "servicing" at the hands of someone who has no right even

owning tools much less USING them.

[jeff_guthrie]

It sounds like one of the element groups is not seated fully, or is not properly adjusted, so they do not come close

enough to reach infinity focus. On FD lenses the rear element group can usually be threaded out as a unit. Possibly

someone took the lens apart to clean it, but did not fully screw in the element group. The front group could also be

incorrectly installed, but this is less likely. Fine adjustments are usually made with a shim which rests between the

front lens group and the lens barrel. If the shim is too thick, the lens will not focus to infinity. Either problem is not hard

to correct.

[rdm]

<p>I have a 50mm 1.2 lens. Currently it has no problems, but if it ever did, or needed a CLA or any work done , I would send it out to "the Lens Doctor".</p>

[theo_bern]

<p>Hello,<br />As I live in a small island (Cyprus), there are NO qualified techs to service any old lens.<br />I've used Eddie aka "Lens Doctor" with EXCELLENT results. Although his last repair was unsuccessful and I was quite unhappy about the results, even though he refunded me the paid amount upon complaining. I am referring to a Canon FD 28-85mm f/4 that came back serviced and was still "wobbly" and not focusing correctly. Anyway no hard feelings and I will use him AGAIN if I need to.<br />Referring to your question, my experience (as I've learned to service them myself), is that if a careless tech serviced the lens before, HOPEFULLY the focusing ring ONLY can be a little mm's OFF.<br />My last experience was with an FD 50mm SSC f/1.4 Breechlock, as it was not focusing to infinity AT ALL. All I did was to carefully reposition the focusing ring to the correct markings (without touching the optics and with LOT'S of measuring and tests) and PRESTO ... the lens was back in order focusing correctly throughout the scale, probably the focusing ring was not secured down correctly as the screws came right off without any resistance.<br />This very lens sold to a guy from the States and because he was very careful with his purchases, had the lens checked from Camera Repair U.S and they told him that the lens was SPOT ON :)<br />Hope this helps.</p>