split focus screen is optibright required?

adwb · 01-29-2010, 06:09 AM

Hi, some help please, having gone the cheap route and bought a split screen from virtual village Split Image Focus Screen for Pentax K10D | Virtual Village - US
[which turns out to have been a bad buy as the screen is way out compared to the auto focus] it does however seem that there are times with a tele lens and
zoom lens that the the lower half of this split screen goes black. is this a common fault or if I get a decent screen from say Katz their very expensive optibright treatment will cure that? or is it a feature of split screens?
thanks
Alistair
,

wildlifephotog · 01-29-2010, 06:13 AM

Split screens all will black out at some point. Usually between 5.6 and f8.
The screen you bought will probably need shimmed to give perfect focus.

adwb · 01-29-2010, 06:29 AM

Originally posted by wildlifephotog

Split screens all will black out at some point. Usually between 5.6 and f8.
The screen you bought will probably need shimmed to give perfect focus.

Oh, OK thanks, now where the h**l do get shims and how thick?
Alistair

wildlifephotog · 01-29-2010, 06:33 AM

The thickness of the needed shims varies. Many folks use post it notes as shims.

GeneV · 01-29-2010, 07:06 AM

Originally posted by adwb

Oh, OK thanks, now where the h**l do get shims and how thick?
Alistair

To me, it was just too much trouble to shim that screen. That one is still sitting in a box somewhere. Two screens from Jinfinance, at about $35US, fit my K10d and K20d without shims. At one point, as a result of a discussion on this board, I set about to test all the Ebay screens and report back. I bought several, but since the Jinfinance was the only one that worked without shimming, I did not get very far with the comparison. I recall one that was so far off that it rattled.

If I were going to plop down the money for Katzeye, I would probably kick in the extra for the brighter coating. So far, the Jinfinance has worked for me.

deejjjaaaa · 01-29-2010, 09:57 AM

Originally posted by adwb

it does however seem that there are times with a tele lens and
zoom lens that the the lower half of this split screen goes black. is this a common fault or if I get a decent screen from say Katz their very expensive optibright treatment will cure that? or is it a feature of split screens?
thanks
Alistair
,

you do not need "optibright" as it has nothing to do with split prism...

any screen cut from Nikon K3 focusing screen blanks (does not matter whether it is cut by katzeye or focusingscreen.com or yourself or another 3rd party) will have better resistance to darkening as Nikon has both prisms somehow "matted" :

http://imaging.nikon.com/...ging/technology/d-archives/history-fm3a/index.htm

translated from Japanese to English

"...In addition, for the manual focusing camera, a special attention has been paid to the focusing screen. It is designed with improved diffusion of transmitted light and also the same technology as adopted in F3 for the central split. The diffusion is increased by the addition of grids onto the smooth split prism surface, thereby eliminating possible blackout even when a slightly darker lens is mounted. Complete blackout of finder image never occurs even when the aperture is stopped down to f/22 and the preview button is pressed..."

BillM · 01-30-2010, 09:53 AM

I paid the premium for it,and it does seem to help,especially at night with my faster
lenses...ie M 50mm 1.4, Tac 135 f/2.5. always in manual focus applications.
Campared to OEM focus screen, a vast improvment.The way Katzeye explains
benifit is in regard to porro and matte portion of screen,which I agree.

JohnBee · 01-30-2010, 10:23 AM

Originally posted by BillM

I paid the premium for it,and it does seem to help,especially at night with my faster
lenses...ie M 50mm 1.4, Tac 135 f/2.5. always in manual focus applications.
Campared to OEM focus screen, a vast improvment.The way Katzeye explains
benifit is in regard to porro and matte portion of screen,which I agree.

I agree Optibright has proven itself enough to retain it's title as the best of the bunch.
However, i think it's worth mentioning that it not only reduces prism blackout but +1 stop to the viewfinder also. Which really comes in handy in low light shooting.

*** updated

Actually according to Katzeye's site, the results of Optibright can be as high as 2+ stops in some cases.
I can't say I've experienced this with our own units, but I guess it happens with a certain camera/lens combination.
Also.. my initial comment of Optibright helping avoid prism black-outs is misleading(as outlined by stevebrot).
Katzeye screens use another method for reducing black-outs which they refer too as "Plus". Which I believe is now on all Katzeye screens by default.

stevebrot · 01-30-2010, 11:38 AM

I have owned the non-Optibrite and currently own the Optibrite versions of the Katzeye screen and can state without reservations that Optibrite does not, in my experience, significantly affect split-image black out. As noted above, that is a characteristic of the split image prism itself. All screens cut from Nikon K3 blanks will resist black out as will the very similar Katzeye product.

Optibrite, on the other hand, is a treatment applied to the screen that enhances screen brightness. According to Rachel Katz, the non-Optibrite version provides a better focus experience with fast glass. If you frequently use slower lenses such as the majority of DA series and most older manual focus zooms, Optibrite will greatly enhance the user experience. As I mentioned, I originally had the non-Optibrite version, but found the viewfinder to be too dim for use with many of my lenses.

Steve

JohnBee · 01-30-2010, 12:26 PM

Originally posted by stevebrot

I have owned the non-Optibrite and currently own the Optibrite versions of the Katzeye screen and can state without reservations that Optibrite does not, in my experience, significantly affect split-image black out. As noted above, that is a characteristic of the split image prism itself. All screens cut from Nikon K3 blanks will resist black out as will the very similar Katzeye product.

I think it's rather easy to confuse the attributes that make the Katzeye so good.
The Optibright(as you pointed out) directly affects the overall viewfinder brightness, whereas the blackouts are part of a what Katzeye refers too as "Plus". Which is a proprietary prism enhancement designed to reduce the effect of blacking-out.

And though I think it's easy to overlook the implications, there is no denying the results of the combination with the Katzeye.

01-29-2010, 06:09 AM	#1
adwb Veteran Member Join Date: Sep 2009 Location: Bristol UK Photos: Gallery Posts: 1,636	split focus screen is optibright required? Hi, some help please, having gone the cheap route and bought a split screen from virtual village Split Image Focus Screen for Pentax K10D \| Virtual Village - US [which turns out to have been a bad buy as the screen is way out compared to the auto focus] it does however seem that there are times with a tele lens and zoom lens that the the lower half of this split screen goes black. is this a common fault or if I get a decent screen from say Katz their very expensive optibright treatment will cure that? or is it a feature of split screens? thanks Alistair ,

01-30-2010, 09:53 AM	#7
BillM Veteran Member Join Date: Jan 2010 Location: Ferguson, Mo. Photos: Gallery Posts: 1,348	Optibrite I paid the premium for it,and it does seem to help,especially at night with my faster lenses...ie M 50mm 1.4, Tac 135 f/2.5. always in manual focus applications. Campared to OEM focus screen, a vast improvment.The way Katzeye explains benifit is in regard to porro and matte portion of screen,which I agree.

01-30-2010, 10:23 AM	#8
JohnBee Veteran Member Join Date: Sep 2008 Location: Newrfoundland Photos: Albums Posts: 4,667	Originally posted by BillM I paid the premium for it,and it does seem to help,especially at night with my faster lenses...ie M 50mm 1.4, Tac 135 f/2.5. always in manual focus applications. Campared to OEM focus screen, a vast improvment.The way Katzeye explains benifit is in regard to porro and matte portion of screen,which I agree. I agree Optibright has proven itself enough to retain it's title as the best of the bunch. However, i think it's worth mentioning that it not only reduces prism blackout but +1 stop to the viewfinder also. Which really comes in handy in low light shooting. *** updated Actually according to Katzeye's site, the results of Optibright can be as high as 2+ stops in some cases. I can't say I've experienced this with our own units, but I guess it happens with a certain camera/lens combination. Also.. my initial comment of Optibright helping avoid prism black-outs is misleading(as outlined by stevebrot). Katzeye screens use another method for reducing black-outs which they refer too as "Plus". Which I believe is now on all Katzeye screens by default. Last edited by JohnBee; 01-30-2010 at 12:31 PM.

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01-29-2010, 06:13 AM	#2
wildlifephotog Inactive Account Join Date: Nov 2008 Location: USA Posts: 924	Split screens all will black out at some point. Usually between 5.6 and f8. The screen you bought will probably need shimmed to give perfect focus.

01-29-2010, 06:29 AM	#3
adwb Veteran Member Join Date: Sep 2009 Location: Bristol UK Photos: Gallery Posts: 1,636 Original Poster	Originally posted by wildlifephotog Split screens all will black out at some point. Usually between 5.6 and f8. The screen you bought will probably need shimmed to give perfect focus. Oh, OK thanks, now where the h**l do get shims and how thick? Alistair

01-29-2010, 06:33 AM	#4
wildlifephotog Inactive Account Join Date: Nov 2008 Location: USA Posts: 924	The thickness of the needed shims varies. Many folks use post it notes as shims.

01-29-2010, 07:06 AM	#5
GeneV Veteran Member Join Date: Oct 2008 Location: Albuquerque NM Photos: Albums Posts: 9,830	Originally posted by adwb Oh, OK thanks, now where the h**l do get shims and how thick? Alistair To me, it was just too much trouble to shim that screen. That one is still sitting in a box somewhere. Two screens from Jinfinance, at about $35US, fit my K10d and K20d without shims. At one point, as a result of a discussion on this board, I set about to test all the Ebay screens and report back. I bought several, but since the Jinfinance was the only one that worked without shimming, I did not get very far with the comparison. I recall one that was so far off that it rattled. If I were going to plop down the money for Katzeye, I would probably kick in the extra for the brighter coating. So far, the Jinfinance has worked for me.

01-29-2010, 09:57 AM	#6
deejjjaaaa Veteran Member Join Date: May 2007 Location: steel city / rust belt Posts: 2,043	Originally posted by adwb it does however seem that there are times with a tele lens and zoom lens that the the lower half of this split screen goes black. is this a common fault or if I get a decent screen from say Katz their very expensive optibright treatment will cure that? or is it a feature of split screens? thanks Alistair , you do not need "optibright" as it has nothing to do with split prism... any screen cut from Nikon K3 focusing screen blanks (does not matter whether it is cut by katzeye or focusingscreen.com or yourself or another 3rd party) will have better resistance to darkening as Nikon has both prisms somehow "matted" : http://imaging.nikon.com/...ging/technology/d-archives/history-fm3a/index.htm translated from Japanese to English "...In addition, for the manual focusing camera, a special attention has been paid to the focusing screen. It is designed with improved diffusion of transmitted light and also the same technology as adopted in F3 for the central split. The diffusion is increased by the addition of grids onto the smooth split prism surface, thereby eliminating possible blackout even when a slightly darker lens is mounted. Complete blackout of finder image never occurs even when the aperture is stopped down to f/22 and the preview button is pressed..."

01-30-2010, 11:38 AM	#9
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	I have owned the non-Optibrite and currently own the Optibrite versions of the Katzeye screen and can state without reservations that Optibrite does not, in my experience, significantly affect split-image black out. As noted above, that is a characteristic of the split image prism itself. All screens cut from Nikon K3 blanks will resist black out as will the very similar Katzeye product. Optibrite, on the other hand, is a treatment applied to the screen that enhances screen brightness. According to Rachel Katz, the non-Optibrite version provides a better focus experience with fast glass. If you frequently use slower lenses such as the majority of DA series and most older manual focus zooms, Optibrite will greatly enhance the user experience. As I mentioned, I originally had the non-Optibrite version, but found the viewfinder to be too dim for use with many of my lenses. Steve

01-30-2010, 12:26 PM	#10
JohnBee Veteran Member Join Date: Sep 2008 Location: Newrfoundland Photos: Albums Posts: 4,667	Originally posted by stevebrot I have owned the non-Optibrite and currently own the Optibrite versions of the Katzeye screen and can state without reservations that Optibrite does not, in my experience, significantly affect split-image black out. As noted above, that is a characteristic of the split image prism itself. All screens cut from Nikon K3 blanks will resist black out as will the very similar Katzeye product. I think it's rather easy to confuse the attributes that make the Katzeye so good. The Optibright(as you pointed out) directly affects the overall viewfinder brightness, whereas the blackouts are part of a what Katzeye refers too as "Plus". Which is a proprietary prism enhancement designed to reduce the effect of blacking-out. And though I think it's easy to overlook the implications, there is no denying the results of the combination with the Katzeye.