IQ of 7d w 15-85mm Vs 6d w 24-105mm?

Started Mar 8, 2013 | Questions thread
MAC
MAC
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Re: What about The Digital Picture.com tests?
In reply to ultimitsu, Mar 12, 2013

ultimitsu wrote:

MAC wrote:

we're talking equivalence across formats . Did you read GB's white paper. The distance from the sensor to the subject when comparing across formats must remain the same.

who is this and what authority does this person hold?

Great Bustard has been with the forum a long time and wrote a great white paper over a long period of time.  You were in the thread - see link below.  Do you challenge this excellent equivalence white paper?  If so, why?  I'm sure those of us who agree with Great Bustard on the distance parameter being held the same would like to hear why?

http://forums.dpreview.com/forums/post/51012476

now we introduce an even more complex subject -- resolution of systems across formats.

dxo messes it up

No they did not.

so you've unfairly penalized crop as well by moving the crop sensor farther away

photozone says -- you can't use their numbers to compare across formats

You misunderstood what photozone meant. What they are saying is you cannot say "Lens EF X which is tested on 5d2 is sharper than Lens EF-S Y which is tested on 50D". Precisely because since Y was tested on 50D it inherently will show less resolution. This goes directly proving Peter's point. There is no discrepancy between DXO and Photozone's view.

No, they said it because moving a sensor backwards to compare different formats is unfair to the format -- see GB's equivalence white paper

but to automatically move the crop camera backward -- when the crop sensor cannot magnify like a lens can -- is just wrong when it comes to comparing across formats

No, you keep saying it is wrong yet you cannot explain why. I already explained to you twice that there is no photo loss due to entropy within 1.6 times distance difference so there is no basis to say it is unfair. You have not provided any counter argument.

I explained it.  GB got it right.  1.6 is not a lens magnifier.  The sensor is cropped off.  Keep the sensor position in the same place to be fair since it is not a lens, it is not a 1.6 lens extender -- it is a sensor.  Photozone recognized the unfairness, and got it right with the disclaimer

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