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11-01-2013, 06:41 AM   #1
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Change focusing screen on K20D without special tool?

I have a bunch of old high quality prime lenses which I like to use with my K20D. I've been working around the well-known problems with erratic metering, but having read that the focusing screen from the *ist DL can give better results, I decided to give it a go. I've managed to pick up a non-functioning, 'for parts only' *ist DL cheap on ebay. Unfortunately I don't have one of the little tools which comes with the focusing screen when you buy one separately. Has anyone got any tips for doing the swap using some other means (like standard household tweezers, for example)? Or will I end up irreparably damaging both focusing screens, and maybe even the camera itself, which is the normal outcome when I take it upon myself to do such a job ?

11-01-2013, 08:10 AM   #2
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If you put some silicone aquarium air hose on a standard tweezers, you will keep from scratching the screen. I replaced the K-10 screen without much trouble. It's a little tricky, but nothing really difficult.
11-01-2013, 08:53 AM   #3
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Really, anything you want to wrap around the end of some standard tweezers to give a little more protection. I have used bare metal tweezers before, just make SURE that you only grasp the screen by the little tab, and that the tweezer points can't slide onto the surface. Once you pull the screen out far enough, you can handle it by the edges with clean fingers, or you can use surgical gloves. Same deal going back in, just use the tweezers for the last little inch or two. Try to work in an area as dust-free as possible or you'll be cleaning everything when you're done. Good luck!
11-01-2013, 09:52 AM   #4
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Thanks, guys. I'll look around and see if I can find something around the house which could serve the function of the silicone air pipe. I'll report back.

11-01-2013, 10:19 AM   #5
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Plain old masking tape wrapped around the ends of the tweezers works fine for me.
11-01-2013, 12:20 PM   #6
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Tape should be fine, too. That tab is the important thing, but sometimes it's difficult to grab correctly.
11-01-2013, 12:47 PM   #7
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The DL focusing screen is a different size due to the pentamirror, I think.
11-02-2013, 06:05 PM   #8
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QuoteOriginally posted by Just1MoreDave Quote
The DL focusing screen is a different size due to the pentamirror, I think.
What he said. IIRC, the *ist screens do not fit the newer cameras.


Steve

11-02-2013, 06:41 PM   #9
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Well, my original thought was that a brand new screen is probably cheaper than buying a parts-only body, not to mention that you can get the exact markings you want, but I figured he'd already bought the body anyway, so why bring it up. I did also wonder about it fitting, since I know not all Pentax screens are inter-changeable.
11-08-2013, 10:05 AM   #10
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Well, it's fitted and working, although I can't say it was a pleasant process. I had difficulty getting the screen out of the *ist DL, and then had difficulty getting the latch to close having put the screen in the K20D. It probably would have been a lot easier with the special tool, and I wouldn't try and do this again without one. Having said that, if the size is, in fact, wrong (it did look slightly bigger), that might explain my difficulty getting the latch to close.

I had read that the screen from the *ist helped the metering problems with manual lenses on the K10D (and, I think K20D) - I believe it was Lowell Goudge on here who mentioned it. Doing a bit more research, though, I get the impression that the screen I need is the one from the *ist DS, and the body I have is a *ist DL. It didn't strike me as a possibility that the focusing screens on the *ist DL and DS might be different sizes, but there are suggestions here - Focusing screens for Pentax DSLR's, period...: Pentax SLR Talk Forum: Digital Photography Review - that they might be.

Anyway, it hasn't proved a magic bullet. The metering appears to be better, but there is still a difference of maybe up to couple of f-stops (on my 135mm M lens) between the exposure set by the green button at f22 and f3.5, and at f8 shots are overexposed by probably half a stop or so. On the positive side, manual focusing is a little easier. I think I may try and get hold of a brand new LL-60 screen which I know fits, and see if that helps. It'll come with the requisite tool!
11-08-2013, 12:29 PM   #11
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QuoteOriginally posted by J2R Quote
Well, it's fitted and working, although I can't say it was a pleasant process. I had difficulty getting the screen out of the *ist DL, and then had difficulty getting the latch to close having put the screen in the K20D. It probably would have been a lot easier with the special tool, and I wouldn't try and do this again without one. Having said that, if the size is, in fact, wrong (it did look slightly bigger), that might explain my difficulty getting the latch to close.

I had read that the screen from the *ist helped the metering problems with manual lenses on the K10D (and, I think K20D) - I believe it was Lowell Goudge on here who mentioned it. Doing a bit more research, though, I get the impression that the screen I need is the one from the *ist DS, and the body I have is a *ist DL. It didn't strike me as a possibility that the focusing screens on the *ist DL and DS might be different sizes, but there are suggestions here - Focusing screens for Pentax DSLR's, period...: Pentax SLR Talk Forum: Digital Photography Review - that they might be.

Anyway, it hasn't proved a magic bullet. The metering appears to be better, but there is still a difference of maybe up to couple of f-stops (on my 135mm M lens) between the exposure set by the green button at f22 and f3.5, and at f8 shots are overexposed by probably half a stop or so. On the positive side, manual focusing is a little easier. I think I may try and get hold of a brand new LL-60 screen which I know fits, and see if that helps. It'll come with the requisite tool!
If I were you, I'd skip the Pentax screens and get a higher performance one from focusingscreens.com As long as you don't get a split-screen it won't affect your metering. I highly suggest a S-type screen (as they are called on their website). They are actually Canon EE-S screens cut down to fit Pentax. I have had one in my last 2 bodies and have another new one waiting to go in my replacement K-3 when it arrives. I will always have one until we get in-VF focus peaking, because that is the only thing that could replace them, IMO. I've had a Katzeye before and greatly prefer these, plus the Katzeye will affect metering. The ones from fs.com come with a variety of tools, shims, etc.. They take a couple of weeks to reach the states.
11-09-2013, 05:29 AM   #12
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QuoteOriginally posted by DogLover Quote
The ones from fs.com come with a variety of tools, shims, etc..
I'm not sure I'd want to be fiddling around with shims, to be honest. Is it tricky to do?
11-09-2013, 10:32 AM   #13
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QuoteOriginally posted by J2R Quote
I'm not sure I'd want to be fiddling around with shims, to be honest. Is it tricky to do?
Well, you kinda have to when you change a screen. Screens vary in thickness, so shimming is how you account for the variance. It's not hard, but can be tedious. The shim goes behind the screen. Trick is finding the exact right thickness shim. It's just lots of trial and error. Pick one to install, confirm that the image is in focus through the VF, take a shot and zoom to confirm, or preferably, view them on your monitor. If it's not right, choose another one and keep track of the ones you have used. If you're not lucky enough to hit on the right one quickly, you'll at least be able to figure out in which thickness direction you need to go, based on what you've tried. The fs.com ones come with several sizes and the right one is most likely in there. If not, you can get a set from Pentax and they are reasonably priced here in the states, less so elsewhere.

Edit: Forgot to mention that when doing these test shots, you need to use your fastest lens, set wide open. You want to eliminate as much of the DoF error margin as possible. The s-screen can discern differences down to f/1.4, possibly even 1.2. Again, this is really not hard to do, it's just tedious unless you get lucky and get the right shim right off the bat. Also, work in as dust-free an environment as you can or you'll need to clean your sensor and/or mirror when you're done. A dry-cleaning with a sensor brush is sufficient since it will just be loose dust particles.

Last edited by DogLover; 11-09-2013 at 01:32 PM.
11-12-2013, 01:55 PM   #14
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I think I may well end up going for one of the Canon S-type screens, I've been reading through some very positive old threads here about them. Whatever happens, I think I'll need to become familiar with shimming, because I've discovered that I now have a pronounced back-focusing problem with my K20D, at least with the Pentax M 50mm 1.7 lens I've been testing it with. When I focus on a bit of text at arm's length and take the shot at f 1.7, I'm finding when I look at the image that the point in sharp focus is about an inch behind where I was focusing. An inch at arm's length seems quite a lot to me. What does this suggest I need to do, in terms of shims? The amount by which it out makes me wonder whether I might have damaged something when fitting the screen.
11-12-2013, 02:19 PM   #15
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Funny thing - completely independently I was after exactly the same thing - having had my K10D for about 6 years I struggled with manual lenses to the point that finally decided to resolve it for good - especially that I am going to keep this camera for as long as it lives. I considered the Katz eye option but that finally went out of scope due to budget reasons. After some planning I decided to try and 'manufacture' my own screen - I didn't know about that canon S screens - but I had an old Super A camera with stuck winding and dead meteer so after I disassembled it - I took the screen out and 'carved' my own - I even recreated that little flange :P - all in all - superb ! No shim required in my case and focus is perfectly accurate - also mat field area is grea - everything pops in focus . Metering problems are still there though.

If you want I can post some details on how I made it and photos of my screen -- manntax


EDIT: I did my screen yesterday night :P - here is a quick snap with my K10D shoot at 1.4 - focus was set on mouse cursor


Last edited by manntax; 11-12-2013 at 02:25 PM.
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