Is Phil’s test unfair to D2X, favouring the 5D erroneously?

Started Nov 13, 2005 | Discussions thread
Bill Janes
Senior MemberPosts: 1,510
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Re: Lines per picture height
In reply to Robert Gonzalez, Nov 16, 2005

Robert Gonzalez wrote:

The lph is the problem I am having. It does not allow you to
compare an APS sensor to a full frame sensor. Or any sensors that
are dimensionally different. If you look at his comparisons, he is
attempting to do just that. He compares the "extinction
resolution" between the 20D and the 5D here:

http://www.dpreview.com/reviews/canoneos5d/page31.asp

And both res chart images were taken so that the filled up the
sensor area basically (from what I can tell). This is not an
apples to apples comparison in my book.

I'm sorry, but I don't get your point. The standard way to report digital camera resolution is in line pairs / picture height since it allows comparisons to be made of cameras with different physical sensor sizes.

To have equal resolution per picture height, a 35 mm camera needs to resolve many more lp/mm on the film than does a 4by5 inch view camera. You might want to take a look at Normal Koren's explanation:

http://www.imatest.com/docs/sharpness.html

For another way to view Phil's tests, refer to my previous thread:

http://forums.dpreview.com/forums/read.asp?forum=1032&message=15853526
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Bill Janes

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