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04-18-2019, 02:25 PM   #1
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Will a different focusing screen help?

Hello
This is my first post. In Ludlow, UK, there is a photographic stall on the Friday market, which is the best I’ve ever seen for retro equipment, where I took some old Canon non auto lenses to sell. The proprietor told me about Pentax and their ability to use lenses going back 50 years. I remembered the Beatles film “A Hard Day’s Night” and how Ringo Star had a Pentax camera. As I like old dinosaur cameras (my main one is an EOS 50d, I opted for another one and bought a K10d together with several manual lenses with the A setting. I particularly wanted a 50mm f1.4, but settled for the 1.7. But, and it’s a big but, I cannot get a sharp focus on any of them especially when wide open. I have adjusted the diopters, tried both eyes, had the viewfinder focus confirmation, seen a pin-sharp viewfinder image and got a blurred result . I had the same problem using m42 lenses with an adapter on my Canon.
Why is this? Will a different focusing screen help? (I remember split image and micro-prisms on a Chinon).
Is there a screen which will serve me best? I have been quoted £40 by a technician to change it if I supply the screen. Is this a fair price or could I do it myself? Finally, would I retain it in use for auto lenses?

04-18-2019, 02:41 PM   #2
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Moved to a new thread for better visibility
04-18-2019, 02:57 PM   #3
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Potentially, but you should check that your diopter is set correctly first. Also, I don't recall if the k10d has catch-in-focus, but it makes working with vintage lenses an absolute pleasure.
04-18-2019, 03:15 PM - 1 Like   #4
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Welcome to the forums

In my experience, film-era focusing screens in DSLRs swap one problem with another. Yes, they can help with manual focusing accuracy... but they introduce metering issues, especially with spot metering.

Instead, I would recommend an O-ME53 magnifying eyepiece for your camera's viewfinder. It's not a magic wand - it won't guarantee perfect focus - but it will magnify the viewfinder enough to make manual focusing easier / more accurate. I have one fitted to every Pentax camera I own

04-18-2019, 03:25 PM   #5
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I have one in my K10, which I bought specifically for use with the 50 1.7 and now use it happily with my tak 1.4. I have no idea about the brand at all sorry, something cheap ($40usd or so) from ebay by memory - it was specifically for the K10, it wasn't adapted from something else.
It has a diagonal split line in a circle in the middle which is surrounded by a micro-prism ring, and it makes manually focusing way way easier, the original screen is really hard to use compared to modern cameras and it doesn't really show depth of field below about 2.8.

The K10 just has focus confirm, no catch in focus or anything fancy like that.

Mine came with instructions for installation and a wee plastic tool, so I did it myself, it took about 5 minutes to do and for me was dead easy - 40 quid seems like a rip off to me unless you have severely shaky hands or trouble gripping small things.

It is pretty straight forward, something like;
Mirror lock up.
Flip camera over.
Use tool or screw driver to un-clip screen.
Use tweezers to remove old screen (put it somewhere safe).
Put new screen in using tweezers making sure brass shim is in place.
Press down till it clicks.

That's about it.

Keep in mind that you need to get the shims and screen positioned correctly, it can affect auto exposure, and some people say it can affect auto focus - I haven't had problems with any of these things but then I usually use my K10 in all manual mode.
04-18-2019, 03:55 PM   #6
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QuoteOriginally posted by sqrrl Quote
The K10 just has focus confirm, no catch in focus or anything fancy like that.
My K10D did just fine with catch-in-focus. It was on that camera that I learned the technique. Here is a tutorial that discusses the fine points...

Catch-in-Focus Tutorial - Articles and Tips | PentaxForums.com

Note that CIF will not work with lenses having a non-conductive (painted or anodized) base.


Steve
04-18-2019, 04:02 PM   #7
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QuoteOriginally posted by sqrrl Quote
I have one in my K10, which I bought specifically for use with the 50 1.7 and now use it happily with my tak 1.4. I have no idea about the brand at all sorry, something cheap ($40usd or so) from ebay by memory - it was specifically for the K10, it wasn't adapted from something else.
It has a diagonal split line in a circle in the middle which is surrounded by a micro-prism ring, and it makes manually focusing way way easier, the original screen is really hard to use compared to modern cameras and it doesn't really show depth of field below about 2.8.
How do you find accuracy of the various metering modes with the replacement screen? I found I could get away with matrix metering (with some adjustments, depending on the scene), less so with centre-weighted, and all bets were off with spot metering. It was metering inaccuracies that eventually caused me to revert to the original screen...
04-18-2019, 04:04 PM   #8
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QuoteOriginally posted by Gingerthecat Quote
I opted for another one and bought a K10d together with several manual lenses with the A setting. I particularly wanted a 50mm f1.4, but settled for the 1.7. But, and it’s a big but, I cannot get a sharp focus on any of them especially when wide open. I have adjusted the diopters, tried both eyes, had the viewfinder focus confirmation, seen a pin-sharp viewfinder image and got a blurred result .
Welcome to the Pentax Forums!

To have both focus confirmation (uses the cameras AF system) and "pin sharp" in the viewfinder both fail to deliver sharp results would be unusual unless there are serious problems with the camera.

QuoteOriginally posted by Gingerthecat Quote
I had the same problem using m42 lenses with an adapter on my Canon.
That might be a clue. A few questions:
  • What lenses (brand/model/mount) are giving you grief?
  • Are you able to get sharp pictures with an auto-focus lens on your K10D?


Steve


Last edited by stevebrot; 04-18-2019 at 04:16 PM.
04-18-2019, 04:10 PM   #9
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QuoteOriginally posted by BigMackCam Quote
How do you find accuracy of the various metering modes with the replacement screen? I found I could get away with matrix metering (with some adjustments, depending on the scene), less so with centre-weighted, and all bets were off with spot metering. It was metering inaccuracies that eventually caused me to revert to the original screen...
I replaced the screen in my K-S2 and haven't had issues - I tend to shoot in M anyway and check the exposure on the first few shots anyway though.
04-18-2019, 04:15 PM - 1 Like   #10
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QuoteOriginally posted by BigMackCam Quote
How do you find accuracy of the various metering modes with the replacement screen?
@sqrrl likely has good stuff to share, but I figured I might give a small contribution too since I have been using an aftermarket screen (Katz Eye) with split image and microprism for at least a decade. The only metering problems I have had were with spot-metering. As might be expected, the center split does throw things off when using the spot meter mode. Other than that, things are good and comparable to the stock screen.


Steve
04-18-2019, 04:16 PM - 1 Like   #11
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QuoteOriginally posted by Gingerthecat Quote
Will a different focusing screen help?
I had a split-prism screen for my K10D and it worked well. It is an easy job to replace the existing screen. My one did not introduce any exposure errors into the mix when using matrix or CW metering, but spot metering was affected.. it was made by KatzEye in the USA, sadly no longer in business, but if you do go for one I suggest you look for this brand.

I suggest you do some proper experimentation with your camera on a tripod to establish exactly what the problem is:

Check diopter setting
Are you able to achieve infinity focus ? Possibly the lens is at fault.
It may be that the the registration distance of the viewfinder no longer matches that of the sensor. The mirror may be out of alignment or indeed the focus screen my not be seated properly, or even the prism may be damaged I would start by removing the focus screen and replacing it to check (don't touch or wipe the surface of it.) your testing should show if the camera is front or back focussing due to alignment problems.

One final thing I would say is that you are right to stick to "A" series lenses or later. Although you can use M or "K" series lenses with the K10D you will have exposure problems when using the stop-down metering method required for the earlier lenses, even when using the stock focus screen. There was quite a hullabaloo about this when it was released. Funnily enough my KatzEye screen gives better results when using stop-down metering that the stock screen.

---------- Post added 04-19-19 at 12:21 AM ----------

QuoteOriginally posted by BigMackCam Quote
How do you find accuracy of the various metering modes with the replacement screen? I found I could get away with matrix metering (with some adjustments, depending on the scene), less so with centre-weighted, and all bets were off with spot metering. It was metering inaccuracies that eventually caused me to revert to the original screen...
I used a KatzEye screen and had no problems metering except for spot which was unusable.

See my comment above for how the KatzEye was actually an improvement over the stock screen when using stop-down metering with K and M series lenses.
04-18-2019, 04:51 PM - 1 Like   #12
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I found the adjustment to spot metering (on K-20D) was a (reliable) function of f-stop. I have forgotten now as I don't use the camera where I installed the screen much. It is focusingscreen.con product, based on Nikon K-3 screen (ruled with lines and no AF markings) as I recall. It was something like reduce exposure 1 stop at f/2, spot on at f/2.8, minus 1 stop at f/4, minus two at f/5.6 and above. You can easily test a lenses (or lenses) and work it out.

About price, it is about $75.00 (US) and then shipping. Once you have it, it is possible to scratch screen, get dust in, and may need to shim it. For me I think a price of about $50 for someone else to install it would be an attractive alternative.
04-18-2019, 05:14 PM   #13
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Steve - Turns out you're right, it's not seemingly documented in the manual or the menu as far as I know, and it only works with specific lenses in afs, but it does work - I just learned something useful - my K10 is now wearing my 100mm f4 macro.
Info here.
K10D catch in focus - PentaxForums.com

I just spent a good 30 minutes on that :P

BigMacCam - yep, from memory I believe that it threw spot metering out but the others still worked fine, but I can't test this really as my K10 suffered an accidental impact a few years back which seemingly damaged the meter so it consistently overexposes by 4-5 stops in every mode with every lens - that happened well after I installed the split screen, I've used it in manual exposure since about 2015.
04-18-2019, 07:25 PM   #14
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QuoteOriginally posted by sqrrl Quote
Steve - Turns out you're right, it's not seemingly documented in the manual or the menu as far as I know
Nope, there is nothing in the manual; that was back when CIF was first noticed as a happy side-effect of the AF-S logic in Pentax some other dSLRs. It was a completely undocumented at first, but was included as a settable option on the K20D and was even in the Table of Contents, though still without an index entry.

As far as "specific lens", it should work with all manual focus lenses having a conductive base as well as AF lenses having in-lens AF motors and an AF/MF switch on the lens barrel (forces camera to MF mode).


Steve

Last edited by stevebrot; 04-18-2019 at 07:31 PM.
04-18-2019, 07:30 PM   #15
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Since above I mentioned the adjustment to spot metering w/ a fosusingscreen.com screen (K3 w/ grid) in my K20D, I checked my summary notes from the tests, and I had the following. I was metering a midtone (Kodak grey card) and I recall using several lenses and finding similar results with each of them.

Table. Required adjustment in e.v. (vs. lens aperture)
f/2.8** . . . 0
f/3.3 . . . . -1
f/4 . . . . . .-2
f4.7 . . . . .-2.5
f/5.6 . . . . -3
> f/5.6 . . .-3

As a happy accident, this means if you set your exposure by spot metering the brightest area in the scene, no exposure adjustment is required at f/5.6 and above.
_____
** I also recall needing a + adjustment at wider than f/2.8, but I don't find that in my abbreviated notes.

Last edited by dms; 04-18-2019 at 08:50 PM. Reason: Added comment about metering brightest area.
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