Pentax DSLR focusing screen

Big Dave · 07-09-2008, 10:50 AM

Hello,
Does anyone know what the thickness of the focusing is, or could measure a spare screen? I have a couple FF screens from other brands that I would like to rework, but I would like to check the thickness before I pull my screen out. Also here is a good site with instructions on modifing a FF screen for Pentax.

Dave

K10D, new split focusing screen - a set on Flickr

Last edited by Big Dave; 08-10-2008 at 03:44 PM.

Gooshin · 07-09-2008, 11:07 AM

i can tell you the dimensions of a K100D screen....

bnishanth · 07-09-2008, 12:13 PM

I believe it is 1.42 mm for K10D.

Reference: Some seller in ebay selling split focus screen and he was claiming that the normal ones on ebay for Pentax are 1.8mm thick whereas Pentax uses 1.42mm. So the one he supplies are the modified K1000 focus screen which is between 1.35~1.37mm.

Cheers
Nish

Big Dave · 07-09-2008, 03:50 PM

Nish,
That is very useful information. It make me think that the performance differences between sources may be due to slight errors in screen position, due to screen thickness. A thin shim may be necessary with some screens to produce accurate focus. Very interesting.

Dave

Originally posted by bnishanth

I believe it is 1.42 mm for K10D.

Reference: Some seller in ebay selling split focus screen and he was claiming that the normal ones on ebay for Pentax are 1.8mm thick whereas Pentax uses 1.42mm. So the one he supplies are the modified K1000 focus screen which is between 1.35~1.37mm.

Cheers
Nish

**ChipB** · 07-09-2008, 05:46 PM

Originally posted by Big Dave

Nish,
That is very useful information. It make me think that the performance differences between sources may be due to slight errors in screen position, due to screen thickness. A thin shim may be necessary with some screens to produce accurate focus. Very interesting.

Dave

Dave, I know that some of the "Hong Kong" screens being sold come with shims because they're too thin. Good luck with getting the screen "right"!!

Big Dave · 07-09-2008, 07:41 PM

Thanks for the tip Chip. Dave

Originally posted by ChipB

Dave, I know that some of the "Hong Kong" screens being sold come with shims because they're too thin. Good luck with getting the screen "right"!!

Jewelltrail · 07-09-2008, 07:54 PM

Big Dave:

I just measured my original screen for my K20 with a digital micrometer--it is 1.4mm thick, precisely.

I have the screen out because I changed to a split focus prism, one from China. If I recall correctly, from the research I did, the K20 screen is the same thickness but please verify this. Good luck.

Regards,

Ernest

gamgee · 07-09-2008, 11:41 PM

Jewelltrail, could you measure other two dimensions of the K20 original focusing screen?

gamgee · 07-10-2008, 01:41 AM

After looking at the flickr tutorial it seems that he did not bother to replicate protruding tabs on the K10 screen. For what purpose are those? Probably positioning. Does that mean that reworked screen could posibly move inside?

bnishanth · 07-10-2008, 04:07 AM

Originally posted by Big Dave

Nish,
That is very useful information. It make me think that the performance differences between sources may be due to slight errors in screen position, due to screen thickness. A thin shim may be necessary with some screens to produce accurate focus. Very interesting.

Dave

Yes, you would need a shim if you use modified K1000 screen. However many users have used 1.8mm thick Chinese screens and as a result they have lost some brightness on their viewfinder, however they claim that this loss of brightness can be managed with.

I believe the thickness also affects your metering, but not sure,

Cheers
Nish

ghelary · 07-10-2008, 04:35 AM

I ordered mine from Focusing Screen and will receive it from Singapore next week normally.

Focusing screen don't affect AF. But from the site, there is some difference regarding specifications between K10D and K20D.

RiceHigh · 07-10-2008, 06:05 AM

Originally posted by Big Dave

Hello,
Does anyone know what the thickness of the focusing is, or could measure a spare screen? I have a couple FF screens from other brands that I would like to rework, but I would like to check the thickness before I pull my screen out. Also here is a good site with instructions on modifing a FF screen for Pentax.

Dave

K10D, new split focusing screen - a set on Flickr

I suggest if you have the full confidence, detach your original screen and measure it by a precision ruler.

But it should be noted that different "focusing" screen will affect the accuracy of the light meter, as well as the accuracy of manual focus at the matte area too. For details of some of those cases, read this:-

RiceHigh's Pentax Blog: When the Focusing Screen Lies (for Focusing and Metering)

Jewelltrail · 07-10-2008, 10:51 AM

Quote:

gamgee: "Jewelltrail, could you measure other two dimensions of the K20 original focusing screen?"

I measure 25.1 mm for the length, and 17.5mm for the width--not counting the extra width the locating tab would add.

My split prism begins to darken even at f5.6, forcing me to focus at large apertures. I bought from a seller who was recommended by others in this forum. The split prism screen did not come with a shim.

Regards,

Ernest

Big Dave · 07-10-2008, 12:37 PM

Thanks Rice, Your information is very helpful. Dave

Originally posted by RiceHigh

I suggest if you have the full confidence, detach your original screen and measure it by a precision ruler.

But it should be noted that different "focusing" screen will affect the accuracy of the light meter, as well as the accuracy of manual focus at the matte area too. For details of some of those cases, read this:-

RiceHigh's Pentax Blog: When the Focusing Screen Lies (for Focusing and Metering)

RiceHigh · 07-11-2008, 04:35 AM

Originally posted by Big Dave

Thanks Rice, Your information is very helpful. Dave

You're welcome :-)

07-09-2008, 10:50 AM	#1
Big Dave Veteran Member Join Date: Jan 2008 Location: San Antonio, Texas Photos: Gallery Posts: 547	Pentax DSLR focusing screen Hello, Does anyone know what the thickness of the focusing is, or could measure a spare screen? I have a couple FF screens from other brands that I would like to rework, but I would like to check the thickness before I pull my screen out. Also here is a good site with instructions on modifing a FF screen for Pentax. Dave K10D, new split focusing screen - a set on Flickr Last edited by Big Dave; 08-10-2008 at 03:44 PM.

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07-09-2008, 11:07 AM	#2
Gooshin Veteran Member Join Date: Sep 2007 Location: Toronto, the one in Canada. Posts: 5,610	i can tell you the dimensions of a K100D screen....

07-09-2008, 12:13 PM	#3
bnishanth Senior Member Join Date: May 2008 Location: Sydney Photos: Gallery Posts: 223	I believe it is 1.42 mm for K10D. Reference: Some seller in ebay selling split focus screen and he was claiming that the normal ones on ebay for Pentax are 1.8mm thick whereas Pentax uses 1.42mm. So the one he supplies are the modified K1000 focus screen which is between 1.35~1.37mm. Cheers Nish

07-09-2008, 03:50 PM	#4
Big Dave Veteran Member Join Date: Jan 2008 Location: San Antonio, Texas Photos: Gallery Posts: 547 Original Poster	Nish, That is very useful information. It make me think that the performance differences between sources may be due to slight errors in screen position, due to screen thickness. A thin shim may be necessary with some screens to produce accurate focus. Very interesting. Dave Originally posted by bnishanth I believe it is 1.42 mm for K10D. Reference: Some seller in ebay selling split focus screen and he was claiming that the normal ones on ebay for Pentax are 1.8mm thick whereas Pentax uses 1.42mm. So the one he supplies are the modified K1000 focus screen which is between 1.35~1.37mm. Cheers Nish

07-09-2008, 05:46 PM	#5
ChipB Site Supporter Join Date: Nov 2007 Location: Eau Claire, WI Photos: Gallery \| Albums Posts: 2,701	Originally posted by Big Dave Nish, That is very useful information. It make me think that the performance differences between sources may be due to slight errors in screen position, due to screen thickness. A thin shim may be necessary with some screens to produce accurate focus. Very interesting. Dave Dave, I know that some of the "Hong Kong" screens being sold come with shims because they're too thin. Good luck with getting the screen "right"!!

07-09-2008, 07:41 PM	#6
Big Dave Veteran Member Join Date: Jan 2008 Location: San Antonio, Texas Photos: Gallery Posts: 547 Original Poster	Thanks for the tip Chip. Dave Originally posted by ChipB Dave, I know that some of the "Hong Kong" screens being sold come with shims because they're too thin. Good luck with getting the screen "right"!!

07-09-2008, 07:54 PM	#7
Jewelltrail Veteran Member Join Date: May 2008 Location: Rhode Island Photos: Albums Posts: 4,180	Big Dave: I just measured my original screen for my K20 with a digital micrometer--it is 1.4mm thick, precisely. I have the screen out because I changed to a split focus prism, one from China. If I recall correctly, from the research I did, the K20 screen is the same thickness but please verify this. Good luck. Regards, Ernest

07-09-2008, 11:41 PM	#8
gamgee Senior Member Join Date: Jan 2008 Location: Osijek, Croatia Posts: 116	Jewelltrail, could you measure other two dimensions of the K20 original focusing screen?

07-10-2008, 01:41 AM	#9
gamgee Senior Member Join Date: Jan 2008 Location: Osijek, Croatia Posts: 116	After looking at the flickr tutorial it seems that he did not bother to replicate protruding tabs on the K10 screen. For what purpose are those? Probably positioning. Does that mean that reworked screen could posibly move inside?

07-10-2008, 04:07 AM	#10
bnishanth Senior Member Join Date: May 2008 Location: Sydney Photos: Gallery Posts: 223	Originally posted by Big Dave Nish, That is very useful information. It make me think that the performance differences between sources may be due to slight errors in screen position, due to screen thickness. A thin shim may be necessary with some screens to produce accurate focus. Very interesting. Dave Yes, you would need a shim if you use modified K1000 screen. However many users have used 1.8mm thick Chinese screens and as a result they have lost some brightness on their viewfinder, however they claim that this loss of brightness can be managed with. I believe the thickness also affects your metering, but not sure, Cheers Nish

07-10-2008, 04:35 AM	#11
ghelary Veteran Member Join Date: Jul 2008 Location: Paris, France Photos: Gallery Posts: 613	I ordered mine from Focusing Screen and will receive it from Singapore next week normally. Focusing screen don't affect AF. But from the site, there is some difference regarding specifications between K10D and K20D.

07-10-2008, 06:05 AM	#12
RiceHigh Veteran Member Join Date: Nov 2006 Location: Hong Kong Posts: 1,934	Originally posted by Big Dave Hello, Does anyone know what the thickness of the focusing is, or could measure a spare screen? I have a couple FF screens from other brands that I would like to rework, but I would like to check the thickness before I pull my screen out. Also here is a good site with instructions on modifing a FF screen for Pentax. Dave K10D, new split focusing screen - a set on Flickr I suggest if you have the full confidence, detach your original screen and measure it by a precision ruler. But it should be noted that different "focusing" screen will affect the accuracy of the light meter, as well as the accuracy of manual focus at the matte area too. For details of some of those cases, read this:- RiceHigh's Pentax Blog: When the Focusing Screen Lies (for Focusing and Metering)

07-10-2008, 10:51 AM	#13
Jewelltrail Veteran Member Join Date: May 2008 Location: Rhode Island Photos: Albums Posts: 4,180	Quote: gamgee: "Jewelltrail, could you measure other two dimensions of the K20 original focusing screen?" I measure 25.1 mm for the length, and 17.5mm for the width--not counting the extra width the locating tab would add. My split prism begins to darken even at f5.6, forcing me to focus at large apertures. I bought from a seller who was recommended by others in this forum. The split prism screen did not come with a shim. Regards, Ernest

07-10-2008, 12:37 PM	#14
Big Dave Veteran Member Join Date: Jan 2008 Location: San Antonio, Texas Photos: Gallery Posts: 547 Original Poster	Thanks Rice, Your information is very helpful. Dave Originally posted by RiceHigh I suggest if you have the full confidence, detach your original screen and measure it by a precision ruler. But it should be noted that different "focusing" screen will affect the accuracy of the light meter, as well as the accuracy of manual focus at the matte area too. For details of some of those cases, read this:- RiceHigh's Pentax Blog: When the Focusing Screen Lies (for Focusing and Metering)

07-11-2008, 04:35 AM	#15
RiceHigh Veteran Member Join Date: Nov 2006 Location: Hong Kong Posts: 1,934	Originally posted by Big Dave Thanks Rice, Your information is very helpful. Dave You're welcome :-)