Cross platform equivalency

Started Apr 25, 2014 | Discussions thread
OP Rick Knepper Forum Pro • Posts: 15,047
I would be interested in a response to this

Ian Stuart Forsyth wrote:

One thing I don’t see with pentax is fast glass, the fastest I could find in production is F2.8 so this would be like F2.2 on FF

My question, can a FF 1.4 lens stopped down to F2.2 be as sharp as a 645crop F2.8 shot wide open?

My understanding from elsewhere in the thread is that the FF lens has to be 1.3x sharper given the example given. I think a FF 1.4 lens with equivalent settings can be sharper than the MF equivalent, but are they? As Just Another Canon mentioned, the sharpness levels are not equivalent. That's why I asked about comparing MTFs which it looks like GB has confirmed below.

Overall, it would be better to wait for verification from someone with better footing on equivalencies.

would this not give an edge to FF ?

The 24-70 II has crazy sharp corners for a zoom even at f2.8. F2.8 is more than fast enough for landscapes as I shoot them. Will the Pentax lens in question, stopping down to f3.5, be as sharp in the corners?  I'll refer to the MTF charts if I can find them.

If the cropped 645z was a true 645 I could see the advantage of the F2.8, but not having anything faster for the cropped 645 really equals out the playing field in noise and resolution would it not ?

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Rick Knepper, photographer, shooting for pleasure. It is better to have It and not need It than need It and not have It. Various RAW comparisons at Link below. Includes 5D3 vs D800E (new uploads), 5D3 vs. 6D, Zeiss lenses etc.

 Rick Knepper's gear list:Rick Knepper's gear list
Pentax 645Z Canon EOS 5DS R Fujifilm GFX 50S Pentax smc D FA 645 55mm F2.8 AL (IF) SDM AW Pentax DA645 28-45mm F4.5 +6 more
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