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01-20-2020, 02:48 AM   #1
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Pentax 67 focusing screen

Does anybody have any experience with Pentax 67 focusing screens?

I got a second focusing screen and fresnel lens with my pentax 67 a beattie intenscreen with split image.

However, when trying to install the beattie screen with the second fresnel lens (which looks a bit weird in itself, having weird circular reflections on it) I get a bright center but a drastic falloff of brightness towards the edges.

With the stock fresnel lens ( i suppose it is the stock) the falloff is even worse.

With the standard focusing screen, image is same brightness all over.

Which way should a fresnel be installed? rough surface towards mirror ur up?

And the beattie instructions that come with the screen says that the original focusing screen comes in 3 parts (matte screen, fresnel and glass), but there is no glass in my 67... neglectable or problem? Also the matte screen and fresnel of the beattie are also separated, should that be?

I would be glad if anyone could help me out here

01-20-2020, 06:31 PM - 1 Like   #2
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Beattie IntenseScreens are known to induce exposure errors of around 1.5 to 2.0 stops (+/-), variable because of their additional brightness; this is my experience with one that was installed in my EOS 1N in the mid-90s when they were quite the novelty and everybody wanted one! The errors were generally not predictable, and when they did occur, were unforgivable, so it was removed (I probably threw it out...). Beattie screen exposure errors may in some cases be worked-around when using SLRs with matrix/evaluative metering, but the Pentax 67 is rudimentary (albeit capable) in its metering (+2.5 / -2.5 from zero), and exposure compensation must be established through careful trial and error (EC is facilitated much easier using a separate hand-held meter). I do not know anybody who is actively using these screens now.

If the screen is thicker than the standard Pentax 67 screen (with the 3 parts assembled), you will encounter problems mounting the prism and light fall-off (vignetting), or the screws will run out, notwithstanding focus errors. The fresnel size faces down. Additionally after installation, the screen is likely to require collimation: checking for precise focus at 3 points around the central area for near and infinity. Some cameras have three screws to affect this adjustment, others have shims.


My opinion is that on balance of known and potential problems (such as metering errors), it's probably the best action to stay with the standard focusing screen.
01-26-2020, 06:40 AM   #3
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I do intend to stick with the standard screen. My camera did not have the glass protection part, so I made ine out of a picture frame glass. However, now the whole assembly was too thick.
Did the 67 come with only 2 part focusing screen and the 6x7 with the glass part in top???

I am totally confused...
01-26-2020, 06:43 PM   #4
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QuoteOriginally posted by MorizKlonner Quote
[...]
Did the 67 come with only 2 part focusing screen and the 6x7 with the glass part in top???

Dunno. I've only ever wrangled the Pentax 67 and I'm loathe to interfere with anything given its critical importance in my production flow.

Perhaps fellow P6x7 / 67 member Desertscape can come out of hiding and chime in here?

01-31-2020, 08:54 AM   #5
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A Pentax brochure I have shows there were 5 focus mattes made for 6x7/67. All look to be one-piece focus mattes. If you have a TTL prism, a very bright focus matte can affect your metering I believe.
  • All-Matte Field
  • Central Split-Image Grid On Matte Field
  • Central Microprism Grid On Matte Field
  • Cross-Lined Matte
  • Central Microprism Grid On Cross-Lined Matte Field
02-01-2020, 12:31 AM   #6
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QuoteOriginally posted by tuco Quote
A Pentax brochure I have shows there were 5 focus mattes made for 6x7/67. All look to be one-piece focus mattes. If you have a TTL prism, a very bright focus matte can affect your metering I believe.
  • All-Matte Field
  • Central Split-Image Grid On Matte Field
  • Central Microprism Grid On Matte Field
  • Cross-Lined Matte
  • Central Microprism Grid On Cross-Lined Matte Field
The focusing screens all come in one part, as the fresnel and the matte screen are taped together. Mine however were taken apart, I don't know why. Possibly to use its fresnel lens with the beattie screen?
However, there should regardless be another part, meaning the glass protection layer on top of that sandwich, and that is what I am missing.
Usually the screen replacement was done by camera technicians, as it requires recalibration of the focus distance of the screen. I think in my Pentax 67 it was a home job and the glass was possibly lost or broken.
Or there was no glass whatsoever, but that is what I am trying to find out
02-01-2020, 12:04 PM   #7
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FWIW, my RollieCord mfg. ca. 1937 uses a matte focusing screen that is one-piece. The matte is facing down and the smooth glass is facing up. I am unclear why there would be a plain glass layer as it would just add more specular reflections unless very well AR coated. The 645 uses a one piece focusing screen.
02-01-2020, 09:17 PM   #8
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QuoteOriginally posted by MorizKlonner Quote
The focusing screens all come in one part, as the fresnel and the matte screen are taped together. Mine however were taken apart, I don't know why. Possibly to use its fresnel lens with the beattie screen?
However, there should regardless be another part, meaning the glass protection layer on top of that sandwich, and that is what I am missing.
Usually the screen replacement was done by camera technicians, as it requires recalibration of the focus distance of the screen. I think in my Pentax 67 it was a home job and the glass was possibly lost or broken.
Or there was no glass whatsoever, but that is what I am trying to find out

Horror of horrors. There is every chance that a rudderless backyard hack was trying to 're-invent the wheel' by removing and disassembling the focusing screen for some perceived 'improvement', only to botch the entire operation. I can see no evidence of a glass interscreen on my P67 focusing screen, just the fresnel on one side and the smooth surface on the other.

Yes, screen replacement does require calibration with a collimeter to establish correct focus at near, mid and far (infinity) distances with a standard lens (e.g. 104mm or 75mm).

I would be surprised if there was glass in that area of the camera; if the camera was to be subject to rough treatment, such as dropping (itself, a cause of a sequalae of problems) dislodgement of the prism and fracturing of the glass would, I think, be obvious.

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