Why modern cameras can't show DOF lower than 2.8?

www.SGphoto.uswww.SGphoto.us Registered Users Posts: 86 Big grins
edited July 27, 2011 in Cameras
ok, so i've read about this a dozen times, modern cameras with the microprism focus plate in the viewfinder cannot allow the user to see any depth of field lower than 2.8, onlu the older ground glass cameras can. I understand that, but the inner geek wants to know why. Does anyone know of a good write up with diagrams and stuff that explains this well?
My Website:www.SGphoto.us

Comments

  • Matthew SavilleMatthew Saville Registered Users, Retired Mod Posts: 3,352 Major grins
    edited July 27, 2011
    It has to do with the opacity (and therefore the brightness) of the "ground glass" (focusing screen) in your DSLR's prism. You can get replacement focusing screens that DO show you accurate DOF, actually. I've seen one on a Canon 5D mk2 with the 85 f/1.2 L, and it is truly a thing of beauty. According to the owner, it doesn't harm focusing at all with those super-fast primes either! I can ask about the exact focusing screen if you're interested.

    But, the bottom line is that they make regular DSLR focusing screens to be less opaque so that it appears brighter. But, the clearer the focusing screen is, the less the focal plane will capture a true image. It's as if you're simply looking through binoculars, instead of at the ground glass of a traditional medium or large format camera.

    It's just a marketing / sales decision. Manufacturers figure that you'd rather not have to squint, than see accurate DOF.


    =Matt=
    “My first thought is always of light.” – Galen Rowell
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