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08-14-2016, 12:27 PM   #31
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QuoteOriginally posted by m42man Quote
Split prisms are a waste of time, IMHO. They're not accurate enough. The standard K-50 screen is really good at manual focusing. Why would you want to go to the bother (and expense) of replacing it with something that needs an awful lot of setting up (re-shimming etc.)?
Well, mine didn't need shimming - it was spot-on. And I found it to be very accurate - took a little getting used to, for sure, but after that, no problem. The issue I had with the standard focusing screen in my K-5 and K-3 is that I found it difficult to nail manual focus on reasonably (but not particularly) close to mid-distance subjects when using wider lenses (say, 35mm and below). That said, I seem to have improved quite a bit in that regard... but I still found the split-prism screen easier for nailing focus with those wider lenses...

08-14-2016, 12:42 PM   #32
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QuoteOriginally posted by BigMackCam Quote
Well, mine didn't need shimming - it was spot-on. And I found it to be very accurate - took a little getting used to, for sure, but after that, no problem. The issue I had with the standard focusing screen in my K-5 and K-3 is that I found it difficult to nail manual focus on reasonably (but not particularly) close to mid-distance subjects when using wider lenses (say, 35mm and below). That said, I seem to have improved quite a bit in that regard... but I still found the split-prism screen easier for nailing focus with those wider lenses...
You may have a point there - the wider lenses are a pain to focus manually. Whether doing it by eye, or by using the green hexagon, the wider lenses are difficult. It may well be that a split-prism is the way to go in these situations (or else you have to use stopped-down hyperfocal - or other - techniques).
08-16-2016, 11:20 AM   #33
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QuoteOriginally posted by m42man Quote
Split prisms are a waste of time, IMHO. They're not accurate enough. The standard K-50 screen is really good at manual focusing. Why would you want to go to the bother (and expense) of replacing it with something that needs an awful lot of setting up (re-shimming etc.)?
I believe you are misinformed on both points.

Addendum: Most split image screens have a focus sensitivity* of f/1.2. The standard K-50 screen has a focus sensitivity of about f/4. Focus confirmation using the PDAF system on the same camera has focus sensitivity of f/5.6 (by design). As for the trouble of shimming...assessment is easy using magnified live view and/or comparing against the CDAF system. If shims are needed, it is a pain. My original Katz Eye screen required no shims on the K10D. My K-3 did require a different shim to work with the Katz Eye for that camera, but the process was fairly painless once I had a selection of shims in hand.


Steve

* The ability to detect an out-of-focus image (calibration for accuracy assumed)

Last edited by stevebrot; 08-16-2016 at 11:32 AM.
08-17-2016, 02:27 AM   #34
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QuoteOriginally posted by stevebrot Quote
I believe you are misinformed on both points.

Addendum: Most split image screens have a focus sensitivity* of f/1.2. The standard K-50 screen has a focus sensitivity of about f/4. Focus confirmation using the PDAF system on the same camera has focus sensitivity of f/5.6 (by design). As for the trouble of shimming...assessment is easy using magnified live view and/or comparing against the CDAF system. If shims are needed, it is a pain. My original Katz Eye screen required no shims on the K10D. My K-3 did require a different shim to work with the Katz Eye for that camera, but the process was fairly painless once I had a selection of shims in hand.
Are you sure about the f4 bit? I'd assume the screen on my K-m would be about f4, but the screen on the K-50 is SO much better. I suppose the fact that it's a pentaprism viewfinder probably helps too though...

08-17-2016, 12:57 PM   #35
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QuoteOriginally posted by m42man Quote
Are you sure about the f4 bit?
Yes, pretty sure, though I don't have a stock focus screen installed to check before I responded . Confirmation is sort of difficult, but if you have a fast lens (f/2 or faster) you can compare viewfinder depth of field (DOF) wide open to DOF stopped down at f/4. The stock focus screen is optimized for brightness at the expense of the ability to do fine focus and my previous testing showed equivalent viewfinder brightness and DOF in the range f/1.4 - f/4.

QuoteOriginally posted by m42man Quote
I suppose the fact that it's a pentaprism viewfinder probably helps too though...
Yes, the difference is pretty impressive.


Steve
11-12-2016, 07:36 AM   #36
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QuoteOriginally posted by m42man Quote
Split prisms are a waste of time, IMHO. They're not accurate enough. The standard K-50 screen is really good at manual focusing. Why would you want to go to the bother (and expense) of replacing it with something that needs an awful lot of setting up (re-shimming etc.)?
Why? Because presumably in the OP’s experience (and mine, and many others), they’ve been MORE accurate than the standard screen, and my experience has been drop-in (no shims, no bother).

If you’ve had a different experience, fine, but honestly it just seems like you’re trolling. OP was looking for a source, not a “should-I-or-shouldn’t-I” decision.
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