Lens Calibration - My Sigma 70-200 f2.8 HSM II

Dal

Dal

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Darren
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After my last shot I possted a few people noticed it was slightly out of focus.

I then decided I should do a focus test on my Sigma 70-200mm f2.8 HSM II. So I setup my tripod with the camera at 45 degree's to the test sheet.

First up, This is how the lens was before fine tuning the AF for this lens.

LensCalibrationTests-026-0_1024px.jpg


Bigger Here

2nd Shot, this is with the fine tune AF set to +20

LensCalibrationTests-03820_1024.jpg


Bigger Here

Last shot, This is with the fine tune AF set to -20

LensCalibrationTests-039-20_1024px.jpg


Bigger Here


Am I right in thinking that this lens needs to go back to Sigma for calibration as nothing I do get's it quite right, +20 is a near as it gets.
 
I have had the same type of problem with same Sigma lens. May I suggest you try at setting the target card at different distances. If the target is too close you may possibly get a false reading, I did. Sigma quote " Minimum focusing distance of 39 inches " and to test you need to be several feet away. Anyway thats what I found with the same camera. More than likely your readings on the camera scale will come down to +/-14 or there abouts or better

Realspeed
 
Last edited:
neil_g said:
to pre-emt hoppy.. ignore those charts for a start. look up the test with the cereal packet and tape measures.
Click to expand...

You mean this?
http://9digitalcamera.com/3131/depth-of-field-testing-dslrs/

realspeed said:
I have had the same type of problem with same Sigma lens. May I suggest you try at setting the target card at different distances. If the target is too close you may possibly get a false reading, I did. Sigma quote " Minimum focusing distance of 39 inches " and to test you need to be several feet away. Anyway thats what I found with the same camera

Realspeed
Click to expand...

Thanks Realspeed, this was at about 1m distance.
 
Right, just re-done the test with a ruler & Nikon 50mm box lol.

at 0 and +20mm they look the same. If I adjust to -20mm it's miles off. I've got the camera approx 3.4m away from the target.
 
The test sheet you can download from the internet has had some bad reports which is why I purchased the LensCal by Spyder. Not had personal experience of home made measuring so don't know how accurate they are. I set up the Lenscal at a fixed distance on one tripod with the D300 on another at exactly the same height on a level surface, so the angle of the test chart was exactly 45%. I did find you need to try different distances and different f settings to get a mean reading.

Realspeed
 
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