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09-14-2013, 10:50 AM   #1
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viewfinder brightness

I have read on more than one occasion about certain cameras having a dim viewfinder. I have an MZS, Z1P, ME Super and Cosina C1, all FF film and K100D, K20D and K5D in APS-C. If I look through each viewfinder in succession without a lens, the brightness is the same. All the FF cameras have a slightly darker band along the top of the frame which is due to the mirror size (other makes have a similar characteristic). All my cameras except the K100D have pentaprisms. I have come to the conclusion that a lot of people get confused when using lenses with varying maximum apertures. Early focussing screens often have slightly lower light transmission which can account for some of the differences and the amount of magnification would be a factor. I think a lot of b......t is talked on this subject.

09-14-2013, 11:17 AM   #2
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It's all fairly subjective unless you are using some sort of light meter to measure the viewfinder output. That doesn't necessarily make it BS.

My Minolta X-700 seems much brighter than my Pentax K10D even with the pure ground glass (no split image in center) but then Minolta was famous for their microprism gound glass.

Have you done a comparison under low light conditions or with macro lenses on bellows or with teleconverters or slow mirror telephoto lenses?
09-14-2013, 11:29 AM   #3
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Just fitting a lightmeter to viewfinder would only work if a small area of the screen was tested. After all the FF has over twice the area lit. Not having any lens fitted is the easiest way to check the brightness as you need to change cameras fast and I don't have a set of identical lenses to fit to all the cameras at once.
09-14-2013, 11:41 AM   #4
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Well you are right, but I think the argument is more about the size of the viewfinder, its coverage and magnification. And it was important back when Pentax was using pentamirror in some models. And there was a worry that it will be replaced by EVF. I think in the current lineup, all Pentax DSLRs use 100% pentaprism, so the brightness argument for FF doesn't work as well anymore.

Last edited by Na Horuk; 09-14-2013 at 12:54 PM.
09-14-2013, 12:40 PM   #5
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The K100D has the despised pentamirror but I can't tell the difference.
09-14-2013, 01:27 PM   #6
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I happen to think that it won't be long before EVF's are superior, they need more pixels, my Panasonic FZ50 of 2006 vintage has a primitive EVF with low resolution but the self brightening feature in dim conditions is a useful feature I wish my K5 had. I have never tried an up to date EVF to see what progress has been made. Of course it is a little more than just higher resolution required as electronic shutters have some disadvantages over conventional ones. As the viewfinder image in an slr is only a projection of the screen then the quality of that image is governed by whatever surface finish is on the screen. When I ran Olympus cameras alongside Pentax,(had to choose which system to keep, made the right decision) I had a focussing screen for microscopy/ extreme telephoto for microscope work which snapped in and out of focus, but with a 50mm lens did not work at all, the screen looked like plain glass. I have noticed that the Katseye screens for mf lenses are bright.
09-15-2013, 09:03 AM   #7
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Every EFV I've tried still has a lag in response due to image processing, making rapid manual focusing nearly impossible: by the time the image looks to be in focus you have turned the adj too far. You have to wait for the image to catch up with the actual focus. Optical finders are still the only real-time option.
I don't mind a dimmer finder if it lets me judge focus accurately. Most modern finders sacrifice focus accuracy for brightness, trusting the autofocus to work.


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