mike_elek Posted April 20, 2005 Share Posted April 20, 2005 I've posted a <a href=http://host.fptoday.com/melek/zeiss/repair/collimate/collimate.html target=_new>page on collimating lenses</a>. That is, setting infinity focus precisely. It's fairly simple to do, and it's much more accurate than using ground glass and a loupe while peering through the back of the camera.<p> Here's my standard test shot from a Contaflex I that was recently overhauled. Shot on good old Kodak 200. I think I was shooting at about f/5.6 to minimize depth of field.<p><div></div> Link to comment Share on other sites More sharing options...
mike_elek Posted April 20, 2005 Author Share Posted April 20, 2005 By the way, this replicates other instructions that you can find on the Web. But in case anyone is interested, this is how it's done. Link to comment Share on other sites More sharing options...
mskovacs Posted April 20, 2005 Share Posted April 20, 2005 I do this the same way with a Nikon F3HP & 200/4 lens for a little more magnification. A 180/2.8 would be a little brighter. I take a bare tungsten bulb and put that close to the back of the camera with the target to get lots of light. I still like to double check minimum focus on ground glass after infinity collimation because some lenses get "fixed" through lens swaps and such. These kind of "fixes" can throw out the focus tracking throughout the full range. Link to comment Share on other sites More sharing options...
david_richert Posted April 20, 2005 Share Posted April 20, 2005 Well done and Thanks Mike I'll have to stop using my wax paper method as soon as I buy a 35mm for testing. Link to comment Share on other sites More sharing options...
kevin_lee5 Posted April 20, 2005 Share Posted April 20, 2005 Mike: Thank you for the instructions. Now, I can fix my FED Micron 2 (full frame) infinity problem -- I took its front lens element out for cleaning; then, I tried Matt Denton's method but I never get it right. Cheers; Link to comment Share on other sites More sharing options...
Andrew in Austin Posted April 20, 2005 Share Posted April 20, 2005 An excellent contribution. Do follow Mike's advice. I was looking at the 50mm Sonnar and by golly I see the family resemblance to my Jupiter 8. I also notice that you removed the plug/screw that controls the aperture opening on the Yumpin Yupiters. There is one final step upon reassembly. On my Jupiters the aperture ring has to be readjusted afterward, as the aperture marks usually no longer line up at the center mark on the focus scale. Another point, if you have the lens disassembled this far. There is easy access to the lock screws for front element retaining ring. If the lens has dust particles between the elements, it's a great opportunity to remove them. Best Regards - Andrew in Austin, TX Link to comment Share on other sites More sharing options...
connealy Posted April 20, 2005 Share Posted April 20, 2005 Nicely done. Looks like it could put an end to the endless hours of hair-pulling fun I've had while adjusting the focus on my old cameras. Link to comment Share on other sites More sharing options...
nicolas_douez Posted April 20, 2005 Share Posted April 20, 2005 Yes, recently read that on your website, thanks Mike. The lens I'm actually servicing (and is fully taken apart with its mechanical parts soaking in Naphta and its front lens waiting for a slight repolishing) is a collapsible prewar 2/50 CZJ Sonnar, and it's shimmed with two spacers. As far as I have seen there is no collimation to do when reassembling it, am I wrong, am I right ?<div></div> Link to comment Share on other sites More sharing options...
mskovacs Posted April 20, 2005 Share Posted April 20, 2005 The postwar lenses like Mike shows don't use the spacers, rather they have a helical on the rear that butts up against the outer mount. Link to comment Share on other sites More sharing options...
mskovacs Posted April 20, 2005 Share Posted April 20, 2005 Re: collimation, I have a prewar 50/1.5 here that I had to recollimate by taking out some of those shims. Beats me why it wasn't right but it was significantly out compared to my other two Sonnars and Jupiter 8M. Link to comment Share on other sites More sharing options...
marco_vera1 Posted April 20, 2005 Share Posted April 20, 2005 Mike, One question: If I understand correctly on a prewar contax RF you adjust infinity focus by fitting spacers under the lens mount, while on the postwar cameras this adjustment is done directly on the lens? I guess this is why while taking apart my IIIa a few days ago I didn't find any spacers under there.... This seems to be a little strange, theoretically at least, the same lens used on two different bodies could be focusing differently! My Vote goes to the PreWar! Link to comment Share on other sites More sharing options...
mike_elek Posted April 20, 2005 Author Share Posted April 20, 2005 That's correct. The prewar lenses uses foil and copper shims to set infinity focus. With any of the older lenses, it's not a bad idea to ensure that infinity focus is correct, especially if it looks like someone else has done work on the lens. Link to comment Share on other sites More sharing options...
nicolas_douez Posted April 20, 2005 Share Posted April 20, 2005 Marco, I'm not sure I understood correctly what you wrote, but I'm afraid you made a confusion. There are shims under the lens mount of the camera body - whatever the camera is (II, IIa, III, IIIa, 2A, 4, 4A, 4AM...). There are also shims and coils in the prewar lenses to ensure a good collimation of the lens. On the other hand, there are not shims in the postwar Sonnar, but a relief dot in the outer lens barrel that slips into the U of the lens barrel, which has to be collimated before you finish the lens reassembly. To sum up, for servicing the prewar lens, just fill the lens outer barrel with the shims and coils they put in it at the factory (and you've found in it when dissassembling), and you're done (theorically). So it's a mistake to say that the same lens could be well collimated for a body and not for the other. Collimation is universal and an optics and mathematics superlative concept. Right the Mikes ? Link to comment Share on other sites More sharing options...
silent1 Posted April 20, 2005 Share Posted April 20, 2005 I've reset the infinity on several of my folders, and on my Reflex II TLR, with excellent results using a loupe and ground glass substitute at the film plane, but those are larger negatives and a larger image to examine; I don't doubt this is a better way for 35 mm. However -- the 35 mm I most need this on (at least until I get around to a CLA for my M42 135 mm, which doesn't reach infinity) is my Olympus Pen EES-2. After cleaning the aperture to restore basic functionality, despite marking the lens barrel, I've never gotten the focus quite right; at f/11 or smaller, with ISO 400 in good light, it's pretty much okay (really looks fine at f/22), but when it opens up a bit it's pretty obviously focused beyond where I set. Problem is, the shutter doesn't have a B setting; I don't know of any way to lock it open in order to set the infinity. The existing speeds of 1/200 and 1/40 just don't let me see anything. Any suggestions how to hold the shutter open with the front element in place? Link to comment Share on other sites More sharing options...
mike_elek Posted April 20, 2005 Author Share Posted April 20, 2005 The only thing I might suggest is to select the lowes ASA/DIN setting and then hope for the slowest shutter speed possible. And then work really quickly, allowing the image to burn into your brain a bit as you twirl the lens to and fro a slight amount each time. Link to comment Share on other sites More sharing options...
dean_williams Posted April 20, 2005 Share Posted April 20, 2005 This is great info to bring to the attention of the group, Mike. The last half dozen or eight cameras I've reset the inf focus on were done with this method. Worlds easier to get it right the first time than with my old way of doing things, ie: frosted glass and a loupe. The old way worked, but it often took me a number of tries to get it spot on, probably due to my middle aged eyes. Your method is nearly fool proof, (thank goodness, for my sake!). Link to comment Share on other sites More sharing options...
mike_elek Posted April 20, 2005 Author Share Posted April 20, 2005 I re-checked all of my Sonnars last year and found that one was off by a noticeable amount. I had previously set infinity (or so I thought) using ground glass + loupe, which wasn't accurate enough for 35mm. Link to comment Share on other sites More sharing options...
silent1 Posted April 21, 2005 Share Posted April 21, 2005 <i>The only thing I might suggest is to select the lowes ASA/DIN setting and then hope for the slowest shutter speed possible. And then work really quickly, allowing the image to burn into your brain a bit as you twirl the lens to and fro a slight amount each time.</i><p> Mike, the EES-2 has only two shutter speeds -- 1/200, and 1/40. If the light level is too low for f/2.8 at 1/40, the red flag appears in the viewfinder and the shutter won't release (don't forget, this is a 1960s vintage auto-exposure camera). The shutter switches to a fixed 1/40 if I engage the flash aperture settings, but even at 1/40, the image doesn't "burn into my brain" and I can't turn the lens enough to notice -- and then I have to operate the film advance to cock the shutter before I can fire again. Link to comment Share on other sites More sharing options...
mskovacs Posted April 21, 2005 Share Posted April 21, 2005 That is a tough one Donald. If you knew/measured the film to flange distance, could you set the lens up on a jig and set focus with it out of the camera? Link to comment Share on other sites More sharing options...
mike_elek Posted April 21, 2005 Author Share Posted April 21, 2005 Donald, that's a tough one. Here's a theoretical: Remove the rear lens element. Trip the shutter at the slowest speed while lightly pressing a pin against the shutter blades. When the shutter blades open, push them open all the way with the pin or a small dowel. Insert a small collar into the lens to keep them open. Replace the rear lens element. Set focus. Remove rear lens element. Remove collar. Replace rear lens element. Would this work in the real world and not in my fantasy lens collimation world? Hmmm ... Link to comment Share on other sites More sharing options...
richard_p Posted April 23, 2005 Share Posted April 23, 2005 Your method is a great step forward! I looked at a similar method that used a 35mm camera to check the image. I felt that the image was too small to be accurate. With MF, the image is huge and the accuracy is secured. I think I'm going to check my flektogon. Richard Link to comment Share on other sites More sharing options...
arthur_mcculloch Posted May 10, 2005 Share Posted May 10, 2005 Mike I take it that the same method can be used on old folders - I need to collimate an old balda, and was thinking to use a 35mm camera to do the testing, with a long lens. Would that work? Thanks Arthur Link to comment Share on other sites More sharing options...
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