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05-07-2017, 05:20 PM   #1
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Light seals originally on the Pentax 6x7

Hello,

I'm new to the forum, and signed up hoping for help. I recently bought a Pentax 6x7, and ran a roll of film through it today. Afterwards, I removed the TTL prism and noticed that the foam seal was a bit gummy. Not terrible, or falling off; just a bit sticky. I thought it might be a good idea to replace it, so I looked for a kit online. That's when I got confused. First, some kits have you put the foam in different places from other kits. Second, my camera does not have foam seals on the back door or on the part of the camera that the door fits into (different seal kits have you put foam in one or the other of these places, or a mixture of the two) and it looks like it never did: there is no goo or residue of any kind in the channel.

So I have a couple of questions I hope folks here can answer:

1. Did these cameras originally have foam light seals along the back door? (I have owned cameras that have nothing but a light trap, where leaks are stopped just with overlapping metal parts, which the 6x7 seems to have).

2. If I do need seals there, where do they actually go? (A link to instructions for the proper placement would be great).

3. I'll send in the roll of 120 for processing, and see if there are light leaks visible. If there are not, would it make sense to just leave it as it is?

I'm actually thinking of selling the camera already, as I already have too many cameras, and bills to pay. I would not want to sell it if it is not in proper shape.

Thanks very much!

Paul

05-07-2017, 07:30 PM   #2
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On the TTL prism, the light seal is applied to the base of the prism. Some people have applied it direct to the corresponding area on the body where the focusing screen is, but the original method is the base of the prism and this also makes it relatively easier to remove, but "easy" is not a particularly good word! Removing every skerrick of the old foam seal is laborious, tedious, tiring and testing.

A correct light seal kit can be obtained from Asahi Custom Coverings in Japan:

http://aki-asahi.com/store/html/Pentax67/LightSeal/Pentax67LightSeal.php

That kit comes with all the seals needed, in two sets, so if you have a stuff up, you have a second set to fall back on.

See the video on that site to view application of the seals.

Removal of the rear door channel seals is probably the hardest of any job, and personally I don't think it is necessary due to the dovetail design of the channel; I have only seen this channel seal replacement done once on an old 6x7 (not 67) body, and it wasn't an easy task (7-8 hours IIRC with scraping damage done to the channel!).

If you notice streaks or flashes of light on exposed film, don't automatically point the finger at light seals.
Check and double check that you are loading and unloading the roll of film correctly and carefully, so that there is no opportunity for light piping at the top and bottom of the film being loaded. Put your index and thumb finger firmly against the roll as you draw the leader across to the take-up spool; this keeps the roll firm and dramatically reduces the likelihood of invasive light. Similarly, the finished roll should not be removed until the adhesive tab is in place and the film pulled out. Ideally neither loading nor unloading is done in strong direct light.

Do you have the 1969-vintage Pentax 6x7, or the 1989-1990 vintage Pentax 67?

Last edited by Silent Street; 05-07-2017 at 07:37 PM.
05-07-2017, 08:52 PM   #3
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Thanks for the reply! I have an MLU 6x7.

I've replaced light seals on Mamiya RB67 backs, and as you say, it may not be difficult, but it is niggling, and time consuming. I had back surgery not long ago, and sitting for long periods is very hard on me. Replacing the seals would be much harder for me now. Getting the old seals off the door will not be hard, though, because as I said, there is nothing to remove. It is clean and looks like there never was any. The only possibilities that I can see are that either it was never there, or someone removed it in the past, though why they would do that without replacing it is hard to understand.

I'm still wondering if anyone else has seen something similar.

I've packed up the film to send to the processor, and will wait to see how it looks. I have used 120 film pretty often, but loading it into the 6x7 seemed harder than it was in other cameras I have used.
05-07-2017, 09:10 PM   #4
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QuoteOriginally posted by PaulEKinzer Quote
I've packed up the film to send to the processor, and will wait to see how it looks. I have used 120 film pretty often, but loading it into the 6x7 seemed harder than it was in other cameras I have used.
Yes, it is a bit of an art form, a bit tedious at first, loading and unloading these cameras, but with experience comes the benefit of mastering it very efficiently.
I once thought loading the cassette of a Hasselblad 503CXI was a doddle. It was not!

05-08-2017, 10:50 PM   #5
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The film is off in the mail, but I'm still curious to know if anyone else has had a 6x7 without foam seals in the back.

Anyone?
05-09-2017, 02:16 PM   #6
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The early Honeywell/Asahi cameras without MLU had the rear seals.
05-09-2017, 06:43 PM   #7
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Ask Eric at pentaxs.com; Eric services just about all of the Pentax 6x7, 67 and BC-time Honeywell bodies (the ones most likely to have featured seals).
pentaxrepairs@aol.com

The photos of the repairs on the Home-Pentaxs page are confronting. Don't go there is you are squeamish...
05-09-2017, 08:04 PM   #8
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Aha! Thanks, desertscape, for that piece of knowledge! Now I know just which seals to get.

Thanks, too, again, Silent Street, for your help. I'll put Eric's email address in my book.

05-13-2017, 09:42 PM   #9
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The photo below is of the seals in the latest generation Pentax 67 (1989-1990).
The seal on the back cover where the film take-up spool lies only extends a short way across the inside; the cover clamps down into the top and bottom seals of the body (lower left); these very thin seals are exceptionally difficult to remove if/when they require replacement, as I watched them being churned out on an old Pentax 6x7, with lots of damaging scraping to get them out and more than a foible and fumble putting new ones in.

I am often asked why seals on some cameras deteriorate, but others do not. Cameras used/stored in very hot conditions over extended times will have noticeably soft/sticky seals that will have an annoying residue on them in various places, especially that one inside the back cover. Goodness knows how seals fare in extremely cold conditions. I have none of the weather extremes where I am, certainly not tropical, frigid or persistently hot.

Last edited by Silent Street; 07-28-2017 at 05:49 PM.
05-14-2017, 11:37 PM   #10
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Thanks again for the help!

That's what the seals look like on mine, and they are not sticky. Those on the prism are very slightly sticky, but not bad enough that I want to do anything about it; at least not yet. The prism does not jiggle in any way, so I think it's fine.

Paul
02-04-2018, 07:54 AM   #11
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QuoteOriginally posted by Silent Street Quote
On the TTL prism, the light seal is applied to the base of the prism. Some people have applied it direct to the corresponding area on the body where the focusing screen is, but the original method is the base of the prism and this also makes it relatively easier to remove, but "easy" is not a particularly good word! Removing every skerrick of the old foam seal is laborious, tedious, tiring and testing.

A correct light seal kit can be obtained from Asahi Custom Coverings in Japan:

http://aki-asahi.com/store/html/Pentax67/LightSeal/Pentax67LightSeal.php

That kit comes with all the seals needed, in two sets, so if you have a stuff up, you have a second set to fall back on.

See the video on that site to view application of the seals.

Removal of the rear door channel seals is probably the hardest of any job, and personally I don't think it is necessary due to the dovetail design of the channel; I have only seen this channel seal replacement done once on an old 6x7 (not 67) body, and it wasn't an easy task (7-8 hours IIRC with scraping damage done to the channel!).

If you notice streaks or flashes of light on exposed film, don't automatically point the finger at light seals.
Check and double check that you are loading and unloading the roll of film correctly and carefully, so that there is no opportunity for light piping at the top and bottom of the film being loaded. Put your index and thumb finger firmly against the roll as you draw the leader across to the take-up spool; this keeps the roll firm and dramatically reduces the likelihood of invasive light. Similarly, the finished roll should not be removed until the adhesive tab is in place and the film pulled out. Ideally neither loading nor unloading is done in strong direct light.

Do you have the 1969-vintage Pentax 6x7, or the 1989-1990 vintage Pentax 67?
Hello

I also have a Pentax 6x7 and noticed a light streak on the first image of the film. (see attachment)

I first thought about getting that light seal kit but then read your comment on loading the film correctly.
I'm afraid I wasn't loading it properly.. and since I only had a light streak on the very first image of the film I'm suspecting that what I'm doing wrong is that after I put the film in, close the lid and continue winding I stop winding as soon as the pointer is on the orange zero. But when I look at youtube tutorial videos like this one
it seems as if people are winding the film passed zero and only stop when they physically can't continue winding. Which seems to be around 1 or 2 past zero.
Could it be that I got the light streak because i started taking picture on the very first part of the film that might have gotten a bit of light when putting the film in the camera?

I'm glad for any help.
Thanks!
Attached Images
 
02-04-2018, 11:08 AM   #12
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The light leaks I have had from loading mistakes look different from what you show. When using slide film, the leak manifests itself as a bleached out section of the film, running vertically thru the frame, emanating from the edge. Haven't had this happen with print film, so I can't comment on how that would look.
02-04-2018, 03:50 PM   #13
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Loading and unloading a roll of 120 film requires care, because the roll can be affected by light piping, particularly common when loading/unloading in strong daylight.
When loading, put in the spool, pull the tab out and hold your index and middle finger against the top and bottom edges of the roll as you pull the leader across the film gate and onto the take-up spool. Wind the spool to the START line only, close the back and wind on until frame 1 come up; at this stage the winding mechanism will become stiff, with the final movement cocking the shutter.

The Pentax 67 will not fire until the film has wound on to frame #1. Do not force the wind-on beyond this!

The light streak may be a processing error, not one of the camera. Desertscape made the point that in slide film a light-affected film looks different to this. It also does not look like the film has been affected by X-Rays.
09-18-2018, 03:17 PM   #14
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I also have a 6x7 unit that was sent to Mr. Hendrickson in January. I'm curious after viewing the above video (light seals) why the door seals on mine end where they do (see pic below). Seems odd.



For those interested, here are some shots from my first roll:







Thanks,
Z
09-18-2018, 04:58 PM   #15
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Light piping and some sort of residue before or during processing.
There is nothing wrong with the foam seals on your camera.
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