[mst]

Quite nice:



http://www.opticallimits.com/nikon_ff/751-nikkorafs2818ff



-- Markus

[Rover]

That much better on FX than on DX? How come? I remember the results of my dream lens - Sigma 85mm - being similar but not to that degree. I understand that sensor density comes into play but most earlier reviews indicated a different behaviour - just worse borders/corners on FX without such quirks.

[rooster]

[quote name='Rover' timestamp='1340741603' post='19155']

That much better on FX than on DX? How come? I remember the results of my dream lens - Sigma 85mm - being similar but not to that degree. I understand that sensor density comes into play but most earlier reviews indicated a different behaviour - just worse borders/corners on FX without such quirks.

[/quote]



First of all thanks for the review and your efforts!



But then there is the same question over here. Any explanations for the big difference wide open between FX and DX? Other lenses (e.g. 14-24, 85 1.8g) are more comparable (on a qualitative level of course). Makes me wonder how it performs on a D800...



Best regards.

[thxbb12]

Thanks for the reviews Markus!



As the other mentioned, I'm a bit surprised at the performance on DX versus FX. I would have expected the opposite figures actually...

[mst]

If you look at the official Nikon MTF charts for the 28/1.8, there is a dent in the MTF curve, which is well within the DX frame. That dent is likely emphasized with higher frequencies. So, combined with demanding high resolution sensors, the quality-drop off is more pronounced than on the larger sensor with lower pixel density. I have some more lenses in the pipeline that show weaker performance on the D7000 than on the D3x (in the borders and corners). One of the is for example the AF-S 35/1.4.



I'm almost through with the CX review of the 28/1.8. On that very high density sensor, the lens struggles even more, even though it's a much smaller sensor.



-- Markus

[Rover]

Thanks for the clarification Markus. So, can we say that the times of "smaller is better" WRT sensor sizes are over? <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/blink.gif' class='bbc_emoticon' alt=':blink:' />

[mst]

Personally, I always regarded larger sensors as better <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/smile.gif' class='bbc_emoticon' alt='' />



There is no general rule, but smaller sensors with high density can be more demanding than larger ones, yes.



-- Markus

[Rover]

Well, there was a definite pattern of poor border quality of many FX lenses showing up on FX though the quality was fine all the way out on DX (in the Canon scope that I'm more familiar with, 50/1.2 L or 17-40/4 L come to mind). But it's not so certain anymore. Does it depend on lens design (e.g. some lenses having more inherent resolution reserves than the others?) And would the 28/1.8 G behave similarly to the behaviour found in the current DX review, say, on Nikon D800? (36 MP FX is probably almost the same pixel density as 16 MP DX, since the D800 crop mode results in 15 MP pictures)

[Yakim]

[quote name='mst' timestamp='1340742253' post='19158']

If you look at the official Nikon MTF charts for the 28/1.8, there is a dent in the MTF curve, which is well within the DX frame. That dent is likely emphasized with higher frequencies. So, combined with demanding high resolution sensors, the quality-drop off is more pronounced than on the larger sensor with lower pixel density. I have some more lenses in the pipeline that show weaker performance on the D7000 than on the D3x (in the borders and corners). One of the is for example the AF-S 35/1.4.



I'm almost through with the CX review of the 28/1.8. On that very high density sensor, the lens struggles even more, even though it's a much smaller sensor.



-- Markus

[/quote]



And here I was, thinking FF lenses would perform better as sensor gets smaller because it will only use the best part of the lens - the center. Silly me.... <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/sad.gif' class='bbc_emoticon' alt='' />

[Rover]

[quote name='Yakim' timestamp='1341000986' post='19252']

And here I was, thinking FF lenses would perform better as sensor gets smaller because it will only use the best part of the lens - the center. Silly me.... <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/sad.gif' class='bbc_emoticon' alt='' />

[/quote]

It used to be like this in most cases (see the results for Zeiss 16-35 for example) but apparently with some lenses the bigger pixel density of modern DX sensors becomes lethal. Odd it should be this way, of course, but the manufacturers chose to race ahead with more megapixels, and while the new technology is doing better for noise performance, it's apparently killing many otherwise fine lenses by overstretching their resolution capabilities. Catch 22 indeed.