Using old screen in K20

gamgee · 07-11-2008, 03:50 AM

Is it posible to adapt old Pentax ME or Minolta X700 screen for use in K20?
It can be sanded as seen in FLickr tutorial in recent thread, but what about thickness? Could not find info on ME or X700 screen thickness.

*Wheatfield* · 07-11-2008, 07:27 AM

A couple of the guys on another forum I read were cutting down screens from an MX/LX to go into an istD, so it is definitely doable. If you can't find screen thickness info on the net you are pretty much stuck with measuring the comparative thicknesses yourself. I have a hunch that Pentax screens are all the same thickness.

jeffkrol · 07-11-2008, 07:34 AM

Originally Posted by gamgee

Is it posible to adapt old Pentax ME or Minolta X700 screen for use in K20?
It can be sanded as seen in FLickr tutorial in recent thread, but what about thickness? Could not find info on ME or X700 screen thickness.

Thread right below you

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

gamgee · 07-11-2008, 07:46 AM

Yes I saw that thread, but I'm interested in thickness of Pentax ME and Minolta X700 because I have both (non functional

) and I saw this thread on Phillipine Photo forum
How to remove FOCUSING SCREEN of k10d - Digital Photographer Philippines

Lowell Goudge · 07-11-2008, 08:07 AM

I would have to question the logic of this decision. You just spent over $1000 on a very good camera, and are looking to save a few dollars on an optional screen to recover something from a piece of junk.

You have to consider that regardless of whether you can make the screen fit and focus manually, there is another problem, specifically metering.

I am not 100% sure on the K20, but on the K10D Pentax do some compensation in software for the exposure calculation based upon maximum apature.

If you want to prove this for yourself, take any lens you own, that can be taken out of "A" and use green button metering at each click of the apature. Take a set of shots at each physical click, and check the grey scale level. Repeat this in A mode, using electronic controlled apature. They will be quitre different, especially if your "test" lens is fast

*Wheatfield* · 07-11-2008, 09:29 AM

Originally Posted by Lowell Goudge

I am not 100% sure on the K20, but on the K10D Pentax do some compensation in software for the exposure calculation based upon maximum apature.

If you want to prove this for yourself, take any lens you own, that can be taken out of "A" and use green button metering at each click of the apature. Take a set of shots at each physical click, and check the grey scale level. Repeat this in A mode, using electronic controlled apature. They will be quitre different, especially if your "test" lens is fast

I tested this myself a while back and concluded that the meter is just not accurate as the light levels fall, which is what happens with stopped down metering.

volosong · 07-11-2008, 09:56 AM

I have a MX screen in my K20D. Yes, metering is flawed, especially spot metering. Normal, historic metering mode for me is center weighted anyway. By shooting RAW, the K20D has enough dynamic range that any image worth keeping is easily 'fixed'. Sometimes I wish for center spot metering, but the split screen/microprism collar is more valuable to me.

Big Dave · 07-11-2008, 10:14 AM

Volosong,
Since a FF screen must be cut down to be used in a DSLR, why couldn't the split image aid be positioned below center? This would allow for good spot metering and better view of the subject. I always target my focus and exposure, before framing anyway.

Dave

Originally Posted by volosong

I have a MX screen in my K20D. Yes, metering is flawed, especially spot metering. Normal, historic metering mode for me is center weighted anyway. By shooting RAW, the K20D has enough dynamic range that any image worth keeping is easily 'fixed'. Sometimes I wish for center spot metering, but the split screen/microprism collar is more valuable to me.

Lowell Goudge · 07-11-2008, 10:17 AM

Originally Posted by Wheatfield

I tested this myself a while back and concluded that the meter is just not accurate as the light levels fall, which is what happens with stopped down metering.

It is not a question of light level falling, otherwise the camera would not meter at all even with an A lens. It is a question of the maximum apature and scatter of light from the viewing screen. With smaller maximum apatures, the light hitting the focusing screen is closer to parallel, with a wide apature it hits at a lot of different angles. As a result the sensor, can be hit by not only light from what it is pointing at, but from things "off target". It is highly variable as a function of the focusing screen installed.

If, for example, you put an *istD screen in your K10D, the K10D meters perfectly (i.e. identical to the *istD) with manual apature lenses, but due to the software compensation for the K10D screen (done for A lenses) the metering goes off with an A lens. the difference is each different maximum apature A lens will have a different but constant for that maximum apature, exposure error.

for a reference to how the K10D performs with an *istD screen click here http://www.pentaxforums.com/forums/241716-post69.html

volosong · 07-11-2008, 10:45 AM

Originally Posted by Big Dave

Volosong,
Since a FF screen must be cut down to be used in a DSLR, why couldn't the split image aid be positioned below center? This would allow for good spot metering and better view of the subject. I always target my focus and exposure, before framing anyway.

Dave

Good idea, but I purchased my screen from a dpreview member in Scandinavia who purchased it from that German Pentax distributer while they were still selling them. They no longer supply MX screens, unless you purchase a body from them. This was several years ago, (the screen went into my Ds, then K10D, then K20D). They may not even supply them in new bodies these days. Luckily, KatzEye screens are available.

Center weighted metering is fine with me. That's what I grew up with on my MX.

Lowell Goudge · 07-11-2008, 11:15 AM

Originally Posted by volosong

Good idea, but I purchased my screen from a dpreview member in Scandinavia who purchased it from that German Pentax distributer while they were still selling them. They no longer supply MX screens, unless you purchase a body from them. This was several years ago, (the screen went into my Ds, then K10D, then K20D). They may not even supply them in new bodies these days. Luckily, KatzEye screens are available.

Center weighted metering is fine with me. That's what I grew up with on my MX.

If we want a split image, and a spot metering point, I have to wonder if there can be a small central "spot" in the split image, or perhaps a spot surrounded by some focusing aid like a micro prism, to allow good spot metering and a manual focusing aid?

Big Dave · 07-11-2008, 12:19 PM

Lowell,
Inthe seventies, some SLR manufactures used spot metering throigh a micro prism. I think that it may have been canon. I don't think that it will work with split image aid. Nikon used split image with center weighted metering.

Dave

Originally Posted by Lowell Goudge

If we want a split image, and a spot metering point, I have to wonder if there can be a small central "spot" in the split image, or perhaps a spot surrounded by some focusing aid like a micro prism, to allow good spot metering and a manual focusing aid?

Lowell Goudge · 07-11-2008, 12:25 PM

Originally Posted by Big Dave

Lowell,
Inthe seventies, some SLR manufactures used spot metering throigh a micro prism. I think that it may have been canon. I don't think that it will work with split image aid. Nikon used split image with center weighted metering.

Dave

I agree, that is why I made the suggestion. can there be a clear central dot in the split image focusing, or perhaps use a micro prism spot for a focvusing aid such that spot metering will work. I am hop[ing Rachel Katz or someone else (i.e. a compeditor to her) is looking at this to see what can be done to give spot metering and manual focusing aid

volosong · 07-11-2008, 12:33 PM

Originally Posted by Lowell Goudge

I agree, that is why I made the suggestion. can there be a clear central dot in the split image focusing, or perhaps use a micro prism spot for a focvusing aid such that spot metering will work. I am hop[ing Rachel Katz or someone else (i.e. a compeditor to her) is looking at this to see what can be done to give spot metering and manual focusing aid

Rachel will "modify" one of her designs to suit your needs/desires. She's good about that. It might cost a bit extra, but she is very 'customer friendly'. (Smart businesswoman...gives the customer what he or she wants.) Contact her through her e-mail address on her web site and she'll get back to you, usually within the same day. She really is customer focused and very responsive. Her screens might cost more, but you get good, ol' fashioned customer service with that.