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Old Sep 18, 2012, 1:00 PM   #1
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Default Comparison of Eye-level Viewfinders II

As a follow up to my first post on the subject, here's an update:

The "Magnification" and "Field of View" are straight from the spec sheets of the respective cameras. The "Angle of View (H) (50mm lens)" is the horizontal angle of view of a 50mm lens, focused at infinity, and mounted on the respective bodies. The "AoV x FoV x Mag." is the angle of view of the image in the viewfinder. If the Magnification was 1.00x and the Field of View was 100%, then the "AoV x FoV x Mag." would be the same as "Angle of View (H) (50mm lens)".

Normal visual acuity is 20/20 which is when the human eye is able to resolve detail as small as 1 arc minute, or 1/60 degree. So "Optical Resoution (20/20)" is the number of arc minutes in "AoV x FoV x Mag.". "Opt. Resolution/Degree" is the "Optical Resoution (20/20)" divided by the angle of view, and represents the level of detail the eye can discern in the image in the viewfinder.

The spec sheet for the A3X/A5X gives the electronic viewfinder a resolution of 800x600 (SVGA). So with a horizontal resolution of 800, the electronic viewfinder has a resolution per degree of about 30. Compared to the resolution of the optical viewfinder in the comparable A5X0, the electronic eye level viewfinder isn't nearly as good as the optical eye level viewfinder. The spec sheet for the A77/A65 gives the electronic viewfinder a resolution of 1024x768 (XGA). The horizontal resolution of 1024 gives that electronic viewfinder a resolution per degree of almost 38. That's a big improvement, but still not up to what is visible through an optical viewfinder.

The 'Full Frame' A900 has a wider angle of view, so the optical resolution is actually slightly less than that of the APS-C A5X0 series. The A99 uses the same XGA electronic viewfinder as the A77/A65, but with the A99's wider angle of view, XGA is woefully inadequate for an average person to be able to discern the same detail that would be clearly visible in an optical viewfinder.

I'm disappointed. If you want to sell a dSLR with an electronic viewfinder, it should be better, not worse.
  • The lens is the thing.
  • 'Full Frame' is the new 'Medium Format'.
  • "One good test is worth a thousand expert opinions." - Tex Johnston, Boeing 707 test pilot.

Last edited by TCav; Sep 18, 2012 at 1:05 PM.
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