Calibrating lenses for a specific camera body

conrad (e2 Member)

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5 Feb 2009 - 4:30 PM

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Today I came across something I've never heard before. The seller of a DSLR body says in his description of the camera: "My lenses were calibrated to work on my previous DSLR body and do not autofocus properly on any other body."

I've never heard of something like this. Can someone explain this?

discreetphoton (Site Moderator)

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5 Feb 2009 - 5:05 PM

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Conrad, it's to do with back and front focus issues. It's not always to do with the lenses, sometimes the focus mirrors are the source of the problem, and need an adjustment. However, the lens screws are often easier to adjust, so this was the corrective measure taken. ie. correcting lens focus to fix a camera error. It's not unusual for lens re-calibrations to be done alongside bodies. I had to look into this after finding that my macro lens didn't focus on the right spot with my D80.
The D300's got the fine tuning option as well, so I never bothered sending off the lens in the end.

samfurlong

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5 Feb 2009 - 7:31 PM

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Before the current 1DMKIII / 50D with the microadjustment feature for different lenses this sort of adjustment had to be done by the manufacturer (don't know if any onther company offered the service but I did have mine done by canon). I had one camera calibrated to the 400mm and one to the 70-200. They worked out that the one body when used with the 400 over a distance of 100 yards was about 30 inches out. The images weren't exactly soft before but when the gear had been done there was a marked imporvement.

samfurlong

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5 Feb 2009 - 7:47 PM

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I'll be honest I don't really know what they did, I sent them 2 bodies and 2 lenses and they calibrated one camera to one lens and the other to the other lens. I stuck a sticker on each to remind me which went with which and that was it really.

LenShepherd

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5 Feb 2009 - 7:58 PM

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Steer clear.
Several recent cameras can be made to focus forward or backward of "correct" - if that is what you want.
These adjustments only affect what the auto focus does with a specific body.
Talking specifically Nikon during a long illness I tracked over 300 "allegations" of front and back focus supported by images. It was not until image 320 that I came across a test image where AF is supposed to focus correct.
The rest were no detail or 45 degree targets or single high contrast lines which Nikon (and I believe Canon) have said for around a decade may cause mis focus. I have now seen well over 400 examples with just the one indicating an equipment fault.
This is not the same as saying there is next to no defective equipment - most who have an issue quickly get an exchange or refund.
However if some-one says all their lenses need calibration perhaps they either hit them with a hammer or (more probable) they do not test with sufficient accuracy to get a 100% reliable result.

PeteWilliamson

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6 Feb 2009 - 11:36 AM

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Hmm I read it was just about tolerance's.

The camera and lenses all work with in an acceptable tolerance when they leave canon.. but these tolerance may differ enough when the lens is conected to the camera that a micro adjustment is needed to bring it back in line so to speak.

You can jsut set up on a tripod and whack out a few images with micro adjustment set to 0, then +20 and -20.. just to see what effect it has.. then maybe +10 and -10... when veiewed at 100% there is a very noticable difference in sharpness... interesting if nothing else as you can see your adjutments take effect
There's another article as well that suggests (for the 1dmkIII) to manual focus using Live View and then go back to AF and if the focusing ring moves at all then there is an element of front/back foucsing.. guess depends how accurate your live view focusing is as well

PeteWilliamson

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6 Feb 2009 - 11:40 PM

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Yeah, but we are talking MICRO adjustments here... I've read that it's really not that unusual for all your lenses to require an adjustment.. purely because the tolerance that they leave the factory can vary considerably but to unaware or less picky you just wouldn't notice they were out..
Just my opinion though.

I think the OP is stating that he has had his lenses calibrated for his Camera body and the likely hood of someone else body being the exact same tolerance is slim.