[mst]

Struggles a bit on the large sensor:



http://www.opticallimits.com/nikon_ff/444-nikkor_afd_35_20_ff



-- Markus

[genotypewriter]

[quote name='Nikkor AF 35mm f/2 D (FX) - Review / Test Report - Analysis' timestamp='1297353067' post='6037']

Borders and extreme corners are a very different story, though. Somewhat soft wide open, the resolution surprisingly decreases at f/2.8.[/quote]

I'm pretty sure this is caused by a focus shift.



GTW

[mst]

[quote name='genotypewriter' timestamp='1297383006' post='6049']

I'm pretty sure this is caused by a focus shift.

[/quote]



I'm pretty sure it's not <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/wink.gif' class='bbc_emoticon' alt='' />



-- Markus

[Klaus]

[quote name='mst' timestamp='1297407266' post='6052']

I'm pretty sure it's not <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/wink.gif' class='bbc_emoticon' alt='' />



-- Markus

[/quote]



The curve has a very pronounced wave form with a sub-wave and at f/2 there's simply a sub-wave top at the border test zone. The sub-wave moves out when closing the aperture (thus increasing the quality in the center zone) and a local low enters the border test zone at f/2.8. I we took -say- ~5 center-to-border readings this would probably get more obvious but that's an overkill.



Focus shift is not an issue in our test procedure.

[genotypewriter]

[quote name='mst' timestamp='1297407266' post='6052']

I'm pretty sure it's not <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/wink.gif' class='bbc_emoticon' alt='' />



-- Markus

[/quote]

So how do you guys account for or eliminate focus shifts?



GTW

[mst]

[quote name='genotypewriter' timestamp='1297642716' post='6087']

So how do you guys account for or eliminate focus shifts?

[/quote]



We do careful manual focus bracketing and evaluate the sharpness seperately for each measured location (center/border/corner) and aperture.



-- Markus

[genotypewriter]

[quote name='mst' timestamp='1297668409' post='6092']

We do careful manual focus bracketing and evaluate the sharpness seperately for each measured location (center/border/corner) and aperture.



-- Markus

[/quote]

Thanks, Markus... but could you explain how just manual [url="http://en.wikipedia.org/wiki/Bracketing#Focus_bracketing"]focus bracketing[/url] accounts for focus shifts?



GTW

[mst]

[quote name='genotypewriter' timestamp='1297808328' post='6141']

Thanks, Markus... but could you explain how just manual [url="http://en.wikipedia.org/wiki/Bracketing#Focus_bracketing"]focus bracketing[/url] accounts for focus shifts?

[/quote]



Isn't it obvious? If the bracketing is large enough (from slightly in front of the test chart to slightly behind it) you'll have the measurement spots in focus at any aperture in some shots. This not only eliminates focus shifts from the MTF values, but also field curvature.



Of course it takes a little more than 3 shots <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/wink.gif' class='bbc_emoticon' alt='' />



-- Markus

[Guest]

I have a question on 35/2 vs 17-35/2.8.

From the results I conclude that in some aspects 35/2 apparently might be somewhat worse than the venerable zoom? It is one step faster and much cheaper, but if f/2.8 suffices, 17-35 is very practical range.

Are 17-35 FX tests in the pipeline, - and how do these two compare?

[mst]

[quote name='rudolf' timestamp='1298642477' post='6361']

Are 17-35 FX tests in the pipeline, - and how do these two compare?

[/quote]



Yes, the 17-35 is definitely in the pipeline. However, my own copy is well used and I'm not sure the results are valid.



I would only go for the 35/2 if I needed the extra stop or the way smaller form factor. Or just wouldn't want to shell out the big bucks for the zoom.



-- Markus