Focus shift issue with D7000...
Discussion
Wondering if anyone can shed any light on the situation I'm finding with my D7000 and Sigma 18-50mm F2.8 lens.
Basically what I'm finding is that on the default AF settings, if I want to focus on a close up subject, say within 3ft of the front of the lens, I get front focusing issues. If I then try to focus on something further away, I start to get back focusing issues.
If I focus on a close subject and adjust the AF fine tuning to fix the front focus (+15), I then end up with a camera that back focuses badly on subjects further away. If I focus on a distant subject and adjust the fine tuning to ensure it isn't back focused (-7), I then end up with a camera that front focuses badly on subjects close up.
I can't seem to strike a good medium with this lens on my D7000. I can either had front focused close up subjects or back focuses distant subjects. The focus plane within the lens seems to shift from close up to infinity.
I did a bit of googling and this appears to be an issue, not with the D7000 as such but with how fast aperture zoom lenses work. This is the first constant F2.8 lens I've owned so I know no better really.
Does it sound like the lens may be faulty or is there a way I can set up the lens and focus system to overcome the problem? Or is this The D7000 focus issue everyone speaks of? Bearing in mind that live view with contrast detect AF has no issues working with the lens and being perfectly sharp every time. Only the phase detection seems to struggle...
Cheers
Basically what I'm finding is that on the default AF settings, if I want to focus on a close up subject, say within 3ft of the front of the lens, I get front focusing issues. If I then try to focus on something further away, I start to get back focusing issues.
If I focus on a close subject and adjust the AF fine tuning to fix the front focus (+15), I then end up with a camera that back focuses badly on subjects further away. If I focus on a distant subject and adjust the fine tuning to ensure it isn't back focused (-7), I then end up with a camera that front focuses badly on subjects close up.
I can't seem to strike a good medium with this lens on my D7000. I can either had front focused close up subjects or back focuses distant subjects. The focus plane within the lens seems to shift from close up to infinity.
I did a bit of googling and this appears to be an issue, not with the D7000 as such but with how fast aperture zoom lenses work. This is the first constant F2.8 lens I've owned so I know no better really.
Does it sound like the lens may be faulty or is there a way I can set up the lens and focus system to overcome the problem? Or is this The D7000 focus issue everyone speaks of? Bearing in mind that live view with contrast detect AF has no issues working with the lens and being perfectly sharp every time. Only the phase detection seems to struggle...
Cheers
just been doing a bit more googling and found the adjustments I need to make (front/back focusing adjustment at different focus distances) can be made easily on sigmas docking station... It's only about £40 as well.. Unfortunately doesn't support the older lenses so no good in this case.
Is there any other way I can personally do this or is it a job for sigma?
Is there any other way I can personally do this or is it a job for sigma?
Perhaps Sigma can fix it/re-chip it - it's worth a go.
When I needed a fast wide-angle zoom I didn't want to pay £1,000 for the Nikon 17-55mm f2.8. So I got the Sigma 20-40mm instead, and had similar problems to you. The large aperture will of course (if used) make your DOF shallower and therefore sometimes harder to get subjects in focus - the margin for error is less - BUT the AF should still work correctly.
As the 20-40mm Sigma was unusable in practice I returned it and bought the Nikon 17-55mm instead. 10 years later, I can tell you it's worth it.
When I needed a fast wide-angle zoom I didn't want to pay £1,000 for the Nikon 17-55mm f2.8. So I got the Sigma 20-40mm instead, and had similar problems to you. The large aperture will of course (if used) make your DOF shallower and therefore sometimes harder to get subjects in focus - the margin for error is less - BUT the AF should still work correctly.
As the 20-40mm Sigma was unusable in practice I returned it and bought the Nikon 17-55mm instead. 10 years later, I can tell you it's worth it.
The focus is consistently out though so hopefully can just be calibrated for the differing focus distances. Regardless, it has a 12 month warranty for repair or replace so will be sorted one way or another.
Would love the Nikon 17-55 but as an enthusiast, I just can't justify the cost. I don't make money from taking photographs so it's not like I'll see the money back.
Very happy with the sigma's performance bar the back/front focusing at different distances. If that can be sorted it will be a cracking lens.
Would love the Nikon 17-55 but as an enthusiast, I just can't justify the cost. I don't make money from taking photographs so it's not like I'll see the money back.
Very happy with the sigma's performance bar the back/front focusing at different distances. If that can be sorted it will be a cracking lens.
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