Is 10% MTF usable?

[xato]

I'm considering getting the Olympus 8mm fisheye when it comes out in

a little while. Olympus' published MTF curves show high MTF in the

center at 60 lp but it drops to around 10% at the edges. My question

is whether or not I can use this 10% difference in values? Will the

sensor be able to pick it up? If so, can I use PS to punch up the

apparent sharpness? My thinking is that even with 12 bits of info

per pixel, will this be sensitive enough to pick up a 10% analog

difference in values.

[bobatkins]

12 bits of digital can pick up differences of 0.025% in analog values.

 

However digital and Photoshop are tools, not magic wands. If they were, you could correct the crappiest lens to produce razor sharp images.

 

Bottom line - you can make it better, but you can't make it good.

[eric friedemann]

Someone is welcome to correct me if I'm off the mark, but here is the chart WX refers to:

 

 

http://www.olympus-esystem.com/dea/products/lens/8_35F/mtf.html

 

 

As best I can tell, the Oly fisheye lens has excellent specifications for a fisheye. Though we are not told what aperture setting was used in testing, at what I take to be 20 line pairs per millimeter (lp/mm) (the blue line) the lens scored 93 in the center and 73 at the edge of the frame. Compare this to Photodo's testing at 20 lp/mm of the well-rated 35mm f/2.0 AFD Nikkor, which score 92 in the center and 85 at the edges af f/8.0- and that was a 35mm focal length lens you'd expect to have much better edge sharpness:

 

 

http://www.photodo.com/prod/lens/detail/NiAF35_2D-442.shtml

[warren_kato]

Thanks but the Oly numbers are a little misleading in that if you compare at 20 lp/mm you also have to remember that the sensor is twice as small. So you would have to score 40 lp/mm to be the same.

 

Yes, the digital Zuikos are tested at 20 lp/mm and 60 lp/mm. Canon tests at 10 and 30. PhotoDo tests at 10, 20 and 40. Popular Photo used to test at 30 lp/mm. Also the digital Zuikos are tested wide open and would probably be a little sharper stopped down one stop.

 

<<As best I can tell, the Oly fisheye lens has excellent specifications for a fisheye. Though we are not told what aperture setting was used in testing, at what I take to be 20 line pairs per millimeter (lp/mm) (the blue line) the lens scored 93 in the center and 73 at the edge of the frame. Compare this to Photodo's testing at 20 lp/mm of the well-rated 35mm f/2.0 AFD Nikkor, which score 92 in the center and 85 at the edges af f/8.0- and that was a 35mm focal length lens you'd expect to have much better edge sharpness: >>