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Summicron 90mm Front Focus


DigitalHeMan

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Hi All,

 

I have an old (1974) Canadian 90mm Summicron. I've never really got along with the lens as I found focusing hard and inaccurate. I recently obtained a 1.4 magnifier viewfinder and this has helped me to realise that the main problem I was having is due to front focus - at a distance of a couple of meters the lens is focusing around 4cm in front of the focal point I have chosen.

 

I can send it in and hopefully get it sorted, but I'm assuming it is the lens and not the rangefinder. Would it feasibly be possible for the rangefinder to be out of calibration so that one lens is out of whack, but my other lenses (28mm Summicron, 50mm Summilux) are still spot on? I appreciate a 90mm at 2.0 has relatively little DoF, but the Summilux also has pretty high accuracy requirements at 1.4 and I don't have any issues.....

 

Ideally I would like to test this by putting it on another digital M body to see how the results are - if anyone in the neighbourhood (Netherlands, Amstelveen) would be willing to meet up to let me test it, I would appreciate it :)

 

Thanks

Simon

 

 

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Hi,

I don't have a 90 but I can tell you that if your other lenses focus accurately, then there is no issues with your rangefinder. I would send your 90 to Leica, or a reputable Leica specialist, to calibrate the lens. When I purchased my M9 I sent my 35, 50 and 135 lenses to be calibrated as each one back-focussed to some extent. All are spot on now. You only need to send the lens, no need to also send the camera - no such thing as matching lens and camera.

Jean-Michel

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Hi,

I don't have a 90 but I can tell you that if your other lenses focus accurately, then there is no issues with your rangefinder. I would send your 90 to Leica, or a reputable Leica specialist, to calibrate the lens. When I purchased my M9 I sent my 35, 50 and 135 lenses to be calibrated as each one back-focussed to some extent. All are spot on now. You only need to send the lens, no need to also send the camera - no such thing as matching lens and camera.

Jean-Michel

 

Thanks, that's the confirmation I needed :)

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  • 3 weeks later...

So, to continue with this thread, I recently was able to pick up a latest model Elmarit-M 90mm at a very good price, even after I factor in the inevitable CLA the lens will need. However, I was surprised that this lens also experiences a similar amount of front focus on the M-E!

 

I have emailed with Leica, and they tell me that older lenses often have focussing problems on the digital M range, and that since my other lenses are working OK, it is just a case of sending the lenses with camera to them, and 'the 90mm lenses will then be adjusted directly to your camera.'

 

However, other people have suggested, here, and in other threads, that Leica don't mate the camera to the lens, so, given that these are older lenses and the service charge from Leica will undoubtably be fairly high, it probably makes more sense to have the lenses serviced first of all locally by Wil van Manen to see if he can get them adjusted.

 

I still have a niggling thought though that if I'm experiencing the problem with two different lenses it could still be the rangefinder, but then the other side of my brain says this isn't the case as my other lenses are spot on......

 

Would dearly like to try my lens on another body to confirm this, or try a known-good 90mm on my body..... is there anyone around the Amsterdam area, or elsewhere in NL, that would be willing to meet for a couple of short tests? :)

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Simon, have you tried to verify (with a focus chart) if the front focus you observe is dependant on the f stop you set the lens to ?

 

Hi Luigi,

 

It seems fairly consistent regardless of the f stop that I have chosen. Here are three crops of tests taken at f/2.8, f/4, and f/5.6 respectively. I used the test chart and methodology at Jeffrey Friedl's Blog . Each time I focused on the line at 0, and each time you can see the line of focus is approximately somewhere around 4-5.....

 

Thanks

Simon

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If it is front focusing I doubt a typical CLA will fix it. Sounds like you'll need collimation and focus adjustment. Unless he includes that in his normal CLA, which I think is unusual.

Edited by brusby
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If it is front focusing I doubt a typical CLA will fix it. Sounds like you'll need collimation and focus adjustment. Unless he includes that in his normal CLA, which I think is unusual.

 

 

CLA - clean, lubricate, adjust. Yes he will, although depending on the adjustment needed it may cost a bit extra.

 

 

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I have a similar problem. All my other lenses 28mm cron, 50mm lux and even 135mm tele-elmar are focusing correctly on M9 and only 90mm collapsible f/4 was front focusing. Recently I bought 90mm tele-elmar 2.8 and it is front focusing just like the collapsible one !!

 

Does this mean all 90mm lenses need to be adjusted for digital? (I am assuming that my 135mm was adjusted for digital before I bought).

 

Please let me know how your experience goes. I may have to send mine too.

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  • 3 weeks later...
Will has mailed to say the lenses are ready for collection. Will drive by tomorrow to collect - am looking forwards to see how/if the focussing has improved :)

 

 

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Simon, did it get calibrated?

Let me know how did it go. My 90mm elmarit is also off (just one lens in my collection of 28,50,90,135) !!

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  • 1 month later...

So, to follow up on this thread......

 

90mm Summicron: This now focuses accurately enough at all distances. Part of the focusing mechanism (a shim I think) was broken and needed to be replaced. This is now a usable lens, although it has a huge focus throw compared to my other lenses.

 

90mm Elmarit: Nothing was done to this lens. According to the collimator, the optical axis of the lens is accurate, and the focus on infinity and 1 meter with the collimator is accurate. So there is nothing that can be done to improve the focussing accuracy. However the lens still front focuses - Will confirmed that, but there is just nothing that he can do to improve, if the optical axis is accurate.

 

So I would like some opinions. I could try sending it to Wetzlar, but I'm not really sure if they are going to be able to do anything else, or I can just cut my losses, and sell the lens. Of course, selling it when I know it has a problem isn't the right thing to do (at least I wouldn't feel right about it, other people selling stuff on auction sites seem to have less regard), so I would need to say something about the front focus.

 

My assumption is that the lens is going to work perfectly with the EVF and live view, although I don't have an M to check, so it should still be a very usable lens to M users - it gives very sharp images when the focusing is spot on (i.e. knocking back the focus ring to compensate for the front focus).

 

What would you do? :)

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