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Do-it-yourself centering sanity check
#11
Brilliant! Thanks for the share! <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/biggrin.gif' class='bbc_emoticon' alt='Big Grin' />
#12
So far I have been able to ensure that my Nikkor 50mm f1.4 and my Nikkor 35mm F2 are perfectly centered fully open. I tried through the viewfinder instead of in live view and it also works fine, although you maybe don't see the development quite as clearly, but the VF of the D700 is so luminous that it was no problem. Easier in a store to just use the viewfinder of course. I am quite confident of my primes, but the zooms from Sigma and Tamron may be a diffrent story. I'll keep you posted.



I have now also tried the 105mm f2.8 and the Sigma 24-70 f2.8 and they both seem absolutely fine, allthough I just use the viewfinder. I'll try it all with the tripod later, but I do not expect any different results.<img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/cool.gif' class='bbc_emoticon' alt='B)' />
#13
[quote name='Vieux loup' timestamp='1302094090' post='7448']

I tried through the viewfinder instead of in live view and it also works fine, although you maybe don't see the development quite as clearly, but the VF of the D700 is so luminous that it was no problem.

[/quote]



The viewfinder, especially when not used from a tripod, will not allow reliable results. As Klaus described, one should use a stable tripod and LiveView with large magnification to be sure a lens is ok.



-- Markus
Editor
photozone.de

#14
[quote name='mst' timestamp='1302096663' post='7449']

The viewfinder, especially when not used from a tripod, will not allow reliable results. As Klaus described, one should use a stable tripod and LiveView with large magnification to be sure a lens is ok.



-- Markus

[/quote]



Yep, the viewfinder is rather useless for this.
#15
I was asked why it is easier to spot the problem in a defocused image.



Here's a reference again from the Sony lens.

You can surely spot that the to edges to the top and right appear to be "closer to focus" than the other two which are much softer.





[Image: defocus.jpg]





Here's the in-focus reference again:



[Image: shiftedcentering.jpg]



Just to mention - this is not a rule for the image borders. This is only a sanity check which can be performed on the image center. At the borders we've all kinds of funny aberrations (optical defects) which can, more or less, resemble a centering issue (e.g. field curvature).
#16
OK! <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/rolleyes.gif' class='bbc_emoticon' alt='Rolleyes' /> So I'll redo it all in Live view and with a tripod.
#17
Hi Klaus,

I understood everything except point 6. - MAINTAIN the 5 degree tilt of the edges!



What does it mean?



Kind regards

Denis
#18
[quote name='DenisLV' timestamp='1345794733' post='19848']

I understood everything except point 6. - MAINTAIN the 5 degree tilt of the edges!

[/quote]



In the testimage, the lines are not horizontal and vertical. they are rotated by

5 degrees.



Now, if you setup your camera on the tripod, you could easily apply the

same 5 degrees to the camera so that the lines in the resulting image

would be vertical and horizontal ...



Point 6 says: Do NOT do this ... keep the camera horizontal, so that

the image taken withg the camera shows the same 5 degrees

rotation that was also on the testimage on the computerscreen.
#19
[quote name='Rainer' timestamp='1345833771' post='19850']

In the testimage, the lines are not horizontal and vertical. they are rotated by

5 degrees.



Now, if you setup your camera on the tripod, you could easily apply the

same 5 degrees to the camera so that the lines in the resulting image

would be vertical and horizontal ...



Point 6 says: Do NOT do this ... keep the camera horizontal, so that

the image taken withg the camera shows the same 5 degrees

rotation that was also on the testimage on the computerscreen.

[/quote]

Thanks Rainer
#20
Great info. Thank you.

 

http://www.oukiphoto.com

 

  


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