I haven’t seen many tests of this lense and lensrentals.com and photozone.de are one of the few shops that shows the results. Here they are shot at a standard Imatest distance of 18 feet.
As an aside, the big question is what he is really measuring. Not too many entries on this, but here’s a quick summary:
What is weighted mean for Lensrentals: I’m using the 1.0/0.75/0/25 weighted mean on the maximum number of calculations of 80:20 boxes. I thought 0.25 more appropriate since there are so many edge and corner numbers compared to central 1/3.
How much sharpening is he applying? I measure off unsharpened raws converted by dcraw in Imatest. (So these are worse case numbers since we know sharpening helps alot and they talk about standardized sharpening, so it isn’t clear what he is measuring :-).
For your XXXX/YYYY format is this the Center/Lens Average? In the Imatest SFR test would the following be the magic decoder ring from the SFRPlus module
- Center = Imatest MTF 50 LP/PH
- Center Mean Lens Average = Imatest MTF 50 LP/PH
- Weighted Mean Corner Average = Imatest MTF 50 LP/PH Corner Mean
On a Canon 5D2, here is what you get:
100-400mm at F/5.6 at 400mm. Center is 740, 655 average and 540 corner. These are in line pair per height, so to convert to equivalent megapixels (740*2)^2* (36/24 = 3/2 aspect ratio) = 1480**2 * 1.5 = 3.2MP. These ar emuch lower because of the sharpening difference i think.
400mm F/2.8 at F/4 which is a $12K lense so about the most possible at the center is 935, 865, 740, so taking the average, we get (865*2)^2 * 1.5 = 4.4MP
70-200 F/2.8 IS II is another spectacular lense with center MTF-50 of 875LP/Ih and 755 average.
