Lens calibration question.
- Thread starter Doog
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There is sharpness and focus adjustment in manufacture, basically putting the lens together correctly (which can be put right by the manufacturers) and then there is focus calibration to the camera body, which is something different.
Problems with the former will mean the lens is never properly sharp. With the latter, it's sharp, but the plane of sharp focus is not where it should be which is what you can adjust with micro AF.
Live view focus, using the contrast-detect system off the LCD, works independently of normal AF and should always be spot on. Easy way to compare.
Problems with the former will mean the lens is never properly sharp. With the latter, it's sharp, but the plane of sharp focus is not where it should be which is what you can adjust with micro AF.
Live view focus, using the contrast-detect system off the LCD, works independently of normal AF and should always be spot on. Easy way to compare.
Thanks I need to set up and do some test shots to be sure but I''ve been a little disappointed with pictures from my Sigma 10-20. At f8 and 1000th sec it should be very sharp and it's not IMO. I wouldn't mind spending the money if I thought recalibration would sort it as I've seen some fantastic images taken by others with this lens.
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Very interesting article Frank. I'm trying to work out if I have this issue with one of my lenses or it's a camera operator fault
That's a good read and I had read something similar in another article. If I contact Sigma and they recommend sending the camera with lens i'd be lost without my D90, even if only for a few weeks, but it may well be worth it in the long run.
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That article isn't Canon-specific. Or, if Nikon don't have as many complaints, it could be that their users actually understand the problem.
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On the other hand, Sigma are the biggest selling independent brand and I think they sell more lenses across all fitings than either Nikon or Canon do on an individual basis, so the law of averages is against them.
Good luck focus checking a 10-20mm lens. There's so much DoF on those it's very difficult to check at sensible distances. Equally, it's hard to believe that it's going to be far out off optimum focus in real shooting for the same reason.
On the other hand, Sigma are the biggest selling independent brand and I think they sell more lenses across all fitings than either Nikon or Canon do on an individual basis, so the law of averages is against them.
I suppose that's true
Good luck focus checking a 10-20mm lens. There's so much DoF on those it's very difficult to check at sensible distances. Equally, it's hard to believe that it's going to be far out off optimum focus in real shooting for the same reason.
Problem is though, with so much depth of field you wouldn't expect such loss of sharpness. As I've said I've seen some terrific images taken with this lens but unless I'm just not used to this particular lens, so far it's just not doing it for me. I'll give it another run out at some point today though and see what happens.