Question about Photozone MTF tests NEX5 vs NEX7

Started Apr 14, 2012 | Discussions thread
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Eric_1
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Question about Photozone MTF tests NEX5 vs NEX7
Apr 14, 2012

Hi there,

I've been comparing photozone reviews of lenses they've tested both on the NEX5 and NEX7, and for many of the reviews, corner sharpness in terms of line width per picture height (lwph) is LOWER for the NEX7.

For example, the kit lens 18-55 has an extreme border sharpness of about 1200 lwph at 18mm f3.5 on the NEX7 and 1800 at the same settings on the NEX5.

SEL1855 NEX7 review: http://www.photozone.de/sony_nex/724-sony1855f3556oss?start=1

SEL1855 NEX5 review: http://www.photozone.de/sony-alpha-aps-c-lens-tests/543-sony1855f3556nex?start=1

My understanding of the lwph is that it's the maximum number of line pairs that can be counted across the height of the photo. In that case, shouldn't NEX7 LWPH always be greater than or equal to NEX5 LWPH for the same lens at the same settings?

Or do these results mean a NEX7 print would have lower resolution than an equal sized NEX5 print, when both photos are using the same lens at the same settings?

In the FAQ, Klaus mentions this:

EffectiveResolution = a * b * c * d * LensResolution

What might make sense is if the MTF numbers in the reviews are LENSRESOLUTION, not EFFECTIVERESOLUTION. But I would rather know about effective resolution, as I can't change a,b,c,d on my camera.

Thanks in advance for your help!

 Eric_1's gear list:Eric_1's gear list
Tamron SP 24-70mm F/2.8 Di VC USD Nikon AF-S Nikkor 70-200mm f/4G ED VR Rokinon 14mm f/2.8 IF ED MC +5 more
Sony Alpha NEX-5 Sony Alpha NEX-7
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