[angrypizza]

i saw high mtf or contrast values for some nikon fx lens on this website like the sigma 24-70 2.8 , so i need to know (apart from the fact that these lens will transform from 24-70 to something like 35-110) if those values will remain the same or even get better if the same lens will be applied on a non full frame camera (dx one) like fuji s3 or nikon d90







thanks

[mst]

No, the values we publish, especially the MTF values, are camera specific. Measurements on a different camera will provide different values, since the sensor (pixel density) as well as the digital workflow (RAW conversion, sharpening, etc.) are an unavoidable part of the measurement.



However, you can use the scaling next to the MTF charts as a rough guidance. A lens that produces high MTF numbers on our D3x will most likely deliver very sharp images on a D90, too, since the pixel density is roughly similar. Things will probably change with the next generation of DX cameras, though (higher MP count, thus higher pixel density).



Please note, though, that this is only true for the center sharpness we measure. Border and corner sharpness are measured at different spots of a lens' image circle for FX and DX.



-- Markus

[mst]

Just one more thing: the Sigma 24-70 HSM was not only tested on the D3x, but also on the D200:



http://www.opticallimits.com/nikon--nikk..._28_hsm_dx



-- Markus

[angrypizza]

thank you for your reply, i saw the sigma 24-70 mtf graph with the d3 going somewhere around 3500 LW/PH f1/4 i thought larger fx lenses like this lens would get close to those values even with a dx camera but i can see with the link you gave me its a way lower than that . . disappointing . . so i guess this is a boost that only full frame cameras can provide with these lenses . .



apart from this is there anyway this website can review nikon 35-70 2.8 with a d200 ?if yes who should i contact or post to ask to?

[wim]

[quote name='angrypizza' timestamp='1280426170' post='1394']

thank you for your reply, i saw the sigma 24-70 mtf graph with the d3 going somewhere around 3500 LW/PH f1/4 i thought larger fx lenses like this lens would get close to those values even with a dx camera but i can see with the link you gave me its a way lower than that . . disappointing . . so i guess this is a boost that only full frame cameras can provide with these lenses . [/quote]

This is a sensor limitation, not a lens limitation. A sensor can only resolve according to the MP it has on board, well, for each of its linear measurements (height, width, diagonal) the resolution is half of the number of pixels, and really slightly less due to the fact that we have a Bayer pattern as well.



On top of that there also are the optical laws, which state amongst others that inverse total resolution is equal to the sum of the inverse resolution of the medium (the sensor in this case) and the inverse lens resolution.



This doesn't seem to work entirely well for sensors (in the favour of sensors), due to the fact that the AA-filter is a cut-off filter which allows for higher resolutions to show than we might expect based on calculations, due to this cut-off, namely, much closer to the Nyquist frequency of the particular sensor. IOW, more than we would get or expect from film with a similar resolution. The latter is especially true for the lower MP sensors (< 10 MP for APS-C, less than 15 MP for FF), where resolution of good lenses brings much more than the sensor resolution to the optical equation.

apart from this is there anyway this website can review nikon 35-70 2.8 with a d200 ?if yes who should i contact or post to ask to?

In short, a D200 will never ever reach the resolution of the D3x, becuae ti physically can't, but in combination with a good lens it will likely always perform very close to its limits, or maximum.



Kind regards, Wim

[mst]

[quote name='angrypizza' timestamp='1280426170' post='1394']

thank you for your reply, i saw the sigma 24-70 mtf graph with the d3 going somewhere around 3500 LW/PH f1/4 i thought larger fx lenses like this lens would get close to those values even with a dx camera but i can see with the link you gave me its a way lower than that . . disappointing . . so i guess this is a boost that only full frame cameras can provide with these lenses . .

[/quote]



LW/PH is line widths per picture height. Picture height is measured in pixels, so the (theoretical) maximum in our measurements is the maximum vertical image resolution of the sensor, regardless of its size (FX/DX). So, a 24 MP sensor with a resolution of 6000x4000 pixels shows scales up to 4000 LW/PH while a lower scale sensor (let's say 3750x2500 for a hypothetical 9.4 MP sensor) only scales up to 2500 LW/PH.



That's pure theory, though, there are quite a few factors which can limit the maximum resolution of a sensor and result in lower maximum numbers. A strong anti alias filter usually is the main reason for this, but the RAW conversion used can have a significant impact, too.



-- Markus