Hey guys! Ok, sounds that this is exactly my problem. I will try to file the back of the lens. Thanks a lot for your help and thank you Steve for the link! ages ago (permalink)

Great idea, Max. If you make them 25.5-26mm inner diameter, you can screw them onto the thread and they won't fall off when you remove the lens from the adapter. Very pleased to help you get that excellent lens working the way it should. : ) I think your photos will help clarify the process, too. Originally posted ages ago. (permalink) ekoehler7 edited this topic ages ago.

Is this what you meant by 'wasp', Gekopaca? en.wikipedia.org/wiki/Gadfly_%28social%29 : ) ages ago (permalink)

Hey! Thanks for the tip! I have exactly this problem. Did I understand it correctly... Do I place the shims between the lens and the adapter? I tried it, but it didn't work... Thanks! ages ago (permalink)

Thanks again ekohler7 for helping me discover what was wrong with my Wollensak 25mm f1.5. It now goes to infinity at infinity with the shims. I came up with a very easy way to make shims for the c mount to micro four thirds. I printed the shims on transparency film on my color laser printer. Used transparencies made for a color laser printer. Outer ring: 35mm Inner ring: 27mm Here's the pdf file only about 300KB www.beerlivery.com/cmountshims.pdf They are really easy to cut with sewing / medical scissors. I only used 4 of these shims before it got to infinity @ infinity. Pictures to come soon... ages ago (permalink)

Ah ah! Yes! exactly! Unknown word for a very known concept : Thanks to improve my english! I'm a gadfly, and that gave me a lot of issues in my job! ages ago (permalink)

I've come up with a very effective method of obtaining infinity focus on m4/3 with a cheap c-mount adaptor... I have this Fujinon TV 1.4/25mm machine vision lens (model HF25HA-1B) which is brand new in the box. The lens mounts perfectly on my Beaulieu Super 8 camera, but when I mount it on my GF1 with a Kipon c-mount adaptor the lens focuses past infinity and the lens markings face bottom rather than top. The lens also vignettes a bit on the GF1, but I love the macro capability of this lens... and when focused at minimum distance and mid-iris this lens has very little vignetting. It's also very tiny, and is a very practical lens to carry for impromptu macro moments. I don't want to correct the collimation of the lens to my GF1 by adjusting the position of the rear element because I'd like to continue to use this lens from time to time on my Super 8. So I need to create some shims for the lens for use with the Kipon adaptor on my GF1. I took some thin plastic 'blister pack' from a lens pouch I recently purchased. By 'blister pack' I mean the ubiquitous clear plastic packaging in which items such as batteries arrive. It seems about the thickness of a paper index card, except it's glossy clear plastic. I used a set of calipers and a compass to score a ~26mm circle in the plastic. Then I carefully traced the scored circle with an xacto knife, popped it out, then with scissors I cut another circle around the one made with the xacto knife... so what I had was a clear plastic ring that I could screw onto the c-mount of the lens to serve as a shim. The 26mm inner circumference of the plastic ring fits snug on the lens c-mount, so that I must screw the shim onto the mount and it stays in place with no worry of it falling off. I made two of these because one shim alone did not provide the correction I needed. However, two shims was a bit too much correction. So I needed to back up on the thickness of the shims by possibly several hundredths of a millimeter. I used some 150 grade sandpaper to thin one shim. I sanded both sides of the shim just to the extent that all the gloss on the plastic material was removed. I then checked the lens, shims and adaptor on the camera for infinity focus. It was still a bit too much correction, so I repeated the sandpaper treatment on the second plastic shim. A few additional sanding rounds and checks later and I now have a perfectly seated Fujinon 25/1.4 machine vision lens with Kipon c-mount adaptor on my GF1. The lens markings face up, although not exactly up... at about 11:45 rather than 12o'clock. Close enough. What is most important is that the lens lands on sharp infinity focus when the focus ring hits that infinity stop. The lens fits very snug, with no play and you can't see the shims with the lens mounted. I'm going to pair this Fujinon 25/1.4 with this Kipon adaptor, so it will live on it from now on. When I want to use this lens on my Beaulieu Super 8, all I have to do is remove the adaptor and the shims and it will still mount perfectly because I've made no adjustments to the lens itself. I imagine this would work equally as well on an even cheaper c-mount adaptor. Originally posted at 2:41PM, 16 September 2010 PST (permalink) ekoehler7 edited this topic ages ago.

I didn't notice he was an admin until he closed the thread. Ooops. I was actually trying to be helpful. I wouldn't mind a moment out of my vacation to explain it to him, and to fix his lens... Originally posted ages ago. (permalink) ekoehler7 edited this topic ages ago.

It's also frustrating because the admin closed the thread after making an erroneous statement regarding the collimation of a zoom lens, which deserves correction. lavender.fortunecity.com/lavender/569/lenscollimation.html elekm.net/zeiss-ikon/repair/collimate/ ages ago (permalink)

Hello! I placed several shims between the lens (cosmicar 25mm, f1.4) and adapter but unfortunately it didn't work. Actually I didn't see any difference after placing another shim. (I just can focus objects with a distance of 20cm to 40cm) Could it be a problem with the adapter or could it be a bug in the lens? ages ago (permalink)

Hello hannJo, Shims are useful if your lens is already able to focus on far away objects, but instead of stopping at a position of sharp focus on far away objects at infinity the focus goes soft. This is what we call 'focusing beyond infinity' for lack of a better term. It also affects the distance marks on the focus ring. This is caused when the lens mounts too deep within the adapter. It sounds like you are not able to focus on anything further than 40cm in front of the lens, so you actually have the opposite problem... your lens is mounting too far out from the sensor, which may be caused by a number of things. Have a close look at the rear diameter of the lens housing. If I'm not mistaken, the Cosmicar 25/1.4 requires a bit of modification (some material must be removed from the diameter of the housing, either by grinding or by turning on a lathe) to fit within a C-mount to m4/3 adapter. ages ago (permalink)

Great idea, thanks OP! hannJo- There are different variations of the Cosmicar 25mm f/1.4, but I had one and it required some filing to get it to reach infinity focus. ekoehler7 is probably right, your problem is the opposite- your lens does not screw in far enough. I just got a metal file and filed down the back edge. It also helps to have a cmount adapter with widest opening possible. Here is a good link with background on this (although its for a different lens it still applies to yours)- cjeastwd.blogspot.com/2009/06/adapting-lens-to-fit-mount.... ages ago (permalink)

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While attempting to assist someone with an infinity focus issue on a PK mount to m4/3 adaptor in the Micro Four Thirds cameras using alternative & legacy lenses Flickr group, I realized this same method can be used on bayonet adaptors. However, a strange thing happened... they didn't believe me. An administrator for the group suggested to 'leave the darn thing alone', and acted as if this is too technical a fix to even attempt. Funny, huh? After a bit of disagreement between myself and the administrator, he closed the thread! Wow. Some pretty rigid resistance to gear fixes/modification over there. It's a shame because it'd be very easy to fix the original poster's infinity focus issue had the administrator not interjected. Check it out: www.flickr.com/groups/1084614@N23/discuss/72157624881896511/ Originally posted ages ago. (permalink) ekoehler7 edited this topic ages ago.

I just read the thread; I think you will not spend your vacation with him ;-) Never be a wasp for an admin, or he will close the thread! Originally posted ages ago. (permalink) Gekopaca edited this topic ages ago.

Yes, between the lens and adapter, at the base of the c-mount thread. If it's not working, try a second shim. You may need to sand your shims to get it precise. Best of luck. ages ago (permalink)