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10-19-2009, 08:55 PM   #1
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Is K20d viewfinder larger than K7?

Is this site correct?
Digital SLR Viewfinders: Size, Magnification, Coverage, Crop


10-19-2009, 08:57 PM   #2
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yeah can someone explain 'effective size'.
10-19-2009, 09:07 PM   #3
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The K-7 has a 100% viewfinder and slightly less magnification. 0.95 vs. 0.92 x.
If you consider the Visual angle - the angle a viewed object subtends at the eye - yes it would be marginally less on the K-7 for the same object, at the same distance viewed through the same lens.
10-19-2009, 11:38 PM   #4
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I had briefly both the k20 and the k7, and I made the simple test to put both at the eyes (one left, one right), with the same lens on both (FA 50)...

Well, in the end, the K7 has a slightly larger viewfinder, but it's barely noticeable (I really had to "superpose" them to see the difference).

10-20-2009, 04:07 AM   #5
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Somewhat related:

The veiw finder eye piece on the K20D justs out a bit more from the back of the camera than the K-7. IMHO, the eye peice for the K-7 is too close to the body, and I get shmook (yes that is the official term) from my face on the lcd. Soo, I put the Pentax magnifier loop on the K-7 . My eyes are older than they used to be, so this serves a dual purpose.
10-20-2009, 05:37 AM   #6
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Site is wrong

QuoteOriginally posted by schmik Quote
No, they are too dumb to compute

They compute effective size as follows (they probably don't tell you this, or do they?):

Size_eff = SQRT(coverage) * magnification / cropfactor

There are three errors I am spotting with their table, sorted by increasing severity:
  1. cropfactor is 1.53, not 1.5 (I mean, they quote 3 digit results ...)
  2. The K20D figure contains a computation error
  3. Coverage can be quoted by area or by linear size. Vendors do both. They arbitarily assume it is by area.
Computing with the (wrong) cropfactor of 1.5 and an area coverage, the figures are:

K-7: 0.613
K20D: 0.617 (NOT 0.633) and both become equal. With a linear coverage, K20D would be less.

Computing with 1.53, the figures read:
K-7: 0.601
K20D: 0.605

BTW, the Pentax MX is 0.945 ...
10-20-2009, 01:16 PM   #7
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Thanks Faulk. I didn't try to replicat theire maths. I simply looked at the area of the sensor (the same for both cams, the coverage and the magnification. It was very close between the two and the k20d was infact just a tiny bit larger. This surprised me. I was also more surprised by the numbers on that page.

BTW, I use the magnifier on the eye piece of my k7.... and every time i pick up my ME i shed a small tear of joy!


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