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Front Focus on Summarit 35mm


DigitalHeMan

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Hi All,

 

After having problems with getting sharp images when working wide open with the Summarit 35mm, I have ascertained this evening that the lens does indeed have quite some front focus on - see the attached image for an example (and yes, I am aware of the issues around using this sort of focus chart with a rangefinder, but when doing the same test with a 50 and 90mm summicron the focus is as good as spot on the 0, so I can eliminate tester error here).

 

I never noticed this front focus when using the lens on film cameras, and to be honest I don't really notice it when doing general (street) photography either, as the increased depth of field provided by the longer focusing distance makes up for the front focus. The only time I really have problems with this is when I am using the lens around the closest focus distance, for example when shooting portraits close up.

 

I've read a bunch of articles and forum entries around focus issues, and various posters are suggesting that it is possible to adjust the lens oneself, but I haven't really found a definitive guide to doing this. Or am I better to just have someone else look at it for me? Any idea how much Will van Manen would cost for example? I assume that since my two other lenses are focusing fine, it is definitely the lens that needs adjustment?

 

Thanks for any suggestions.....

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So, after a bit more testing, I've realised the 90mm is also showing a tiny bit of front focus, although nowhere near as severe as the 35mm. I will take both lenses to v Manen tomorrow for them to have a look at them.

 

But this raises a question in my mind...... the 35mm never seemed to cause me any problems on my M6. So why would it be so far out on the M-E when the Summicron 50mm is spot on?

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It's possible that your M-E is front-focussing (certainly wouldn't be the first M digital to have a misfocussing RF out of the box) and that your 50 Summicron is a bit backfocus prone (and the two cancel each other out) but your 35 Summarit test result does look like that lens is quite some way out. If you are going to see a technician you might as well take the body and all three lenses to be checked.

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I'd also suggest you repeat the focus test a few times, carefully removing and mounting the lens between. When you mount the lens make sure to focus to infinity first to withdraw the cam into the lens before mounting.

I've done tests on a lens (tripod mounted, test chart) that would show front focus, then would be fine after remounting and trying again. I'm not sure just what might be variable in the cam/follower linkage, but it seems to happen at times.

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