Pentacon Six & Biometar 80 focus problem

shutterfinger · Nov 28, 2017

If your camera and lens were in my possession I would have
1. set the camera up on my Berlebach or zone 6 tripod and leveled the camera.
2. set up one of the test targets I have on 20 x 30 inch foam core parallel to the film plane.
ISO 12233

, USAF 1951

, multiple 2 inch square copies at various angles in a + and X pattern, or the ones available at http://www.normankoren.com/Tutorials/MTF5.html

3. mounted a ground glass at the film plane and focused the old and new Biometers using an 8x loupe and comparing the results to the view screen using the loupe.

I guarantee all readers that I would have found the focus error within the first hour and possibility had the view screen adjusted so that any lens attached to the body was in perfect focus at the film plane and view screen.
If the body were warped from a drop a more serious focus problem would exist.

Search engine Lens Test Target for full resolution versions and others, print them on a photo printer at its highest resolution.
Glossy photo paper produces the sharpest image.

Tor-Einar Jarnbjo · Nov 29, 2017

shutterfinger said:
If your camera and lens were in my possession I would have
1. set the camera up on my Berlebach or zone 6 tripod and leveled the camera.
2. set up one of the test targets I have on 20 x 30 inch foam core parallel to the film plane.
ISO 12233 View attachment 190943 , USAF 1951 View attachment 190944 , multiple 2 inch square copies at various angles in a + and X pattern, or the ones available at http://www.normankoren.com/Tutorials/MTF5.html View attachment 190946
3. mounted a ground glass at the film plane and focused the old and new Biometers using an 8x loupe and comparing the results to the view screen using the loupe.

I guarantee all readers that I would have found the focus error within the first hour and possibility had the view screen adjusted so that any lens attached to the body was in perfect focus at the film plane and view screen.
If the body were warped from a drop a more serious focus problem would exist.

As you can read further back in the thread, I have already done such a test. With the old lens, the focus on the groundglass in the viewfinder and the groundglass substitute mounted in the film plane matches. With the new lens, I can see the same focus difference in this test, as I can see on the real exposures.

It is also obvious, and it has also been discussed, that I can raise the groundglass to solve the focusing issue with the new lens. If you have a solution to how to do that without ruining the ability to focus with the old lenses, please speak up.

shutterfinger · Nov 29, 2017

If the camera technician you left the camera with does not fix it then send the camera and lens to me and I will.

I have encountered solutions to problems with equipment that defied theory and operation logic.
I believe your body was set up with an f4 lens attached that acted like an f3.8 or 3.9 and your older f2.8 lens is more like a f3 or f3.1 so it appears in focus but the newer lens is more like an f2.6 so its off focus.
I deal more with large format gear and have encountered lens that would hold infinity focus wide open for .001 to .002 inch of focus movement. (.0254 to .0508 mm)

An optical test bench is the best as it can act as an f1 lens.

I prefer the Norman Koren lens test targets for critical focusing test. I have several copies printed on 8x10 paper on the foam core. Different line widths show at different distances and focal lengths.

P.S.
Fewer focusing problems exists when ground glass and focusing screens are set up using an infinity target at least 5000 feet/1524 meters away that has fine detail such as a high rise office building with lots of windows.
Some travel may be necessary to find a suitable target. Use an online map and measure the distance via the scale on the map in a direct line from your location.
The moon and bright stars are excellent infinity targets.

barzune · Dec 6, 2017

Tor-Einar Jarnbjo said:
As you can read further back in the thread, I have already done such a test. With the old lens, the focus on the groundglass in the viewfinder and the groundglass substitute mounted in the film plane matches. With the new lens, I can see the same focus difference in this test, as I can see on the real exposures.

It is also obvious, and it has also been discussed, that I can raise the groundglass to solve the focusing issue with the new lens. If you have a solution to how to do that without ruining the ability to focus with the old lenses, please speak up.

I've been following this thread since the beginning, and am fascinated with the problem.
Have you tried the "adjusted" camera? Has the focusing issue been resolved, with all lenses?
D.

Tor-Einar Jarnbjo · Dec 6, 2017

barzune said:
I've been following this thread since the beginning, and am fascinated with the problem.
Have you tried the "adjusted" camera? Has the focusing issue been resolved, with all lenses?
D.

No, not yet. I'll call tomorrow and ask if the camera is ready and I hope to have time to pick it up. I am usually working so late, that it is difficult to get to the repair shop after work before they close, but I will try to do it either tomorrow or on Saturday. Not sure though when I will have time to actually test it.

moto-uno · Dec 6, 2017

Well, I for one have my fingers crossed for you ! Regards,Peter

John Koehrer · Dec 6, 2017

barzune said:
I've been following this thread since the beginning, and am fascinated with the problem.
Have you tried the "adjusted" camera? Has the focusing issue been resolved, with all lenses?
D.

Me too, it's a real puzzle.

shutterfinger · Dec 7, 2017

Tor-Einar Jarnbjo said:
No, not yet. I'll call tomorrow and ask if the camera is ready and I hope to have time to pick it up. I am usually working so late, that it is difficult to get to the repair shop after work before they close, but I will try to do it either tomorrow or on Saturday. Not sure though when I will have time to actually test it.

Slip out on lunch.

Tor-Einar Jarnbjo · Dec 10, 2017

I picked up the camera on Friday and did a new round of test shots with both the old and the new lenses today. The problem is fixed, I can now actually focus properly with all my lenses. The service shop did not charge more than 35€ for the repair.

The repair guy still insisted that I could never have focused properly with that camera and any lens. Both the mirror and the groundglass were displaced and have now been adjusted. If I understood it correctly, the groundglass was at the right height, but slid sideways, causing the center of the curved surface to be off-center in relation to the projected image.

Theo Sulphate · Dec 10, 2017

An interesting diagnosis. Congratulations on getting the problem fixed!

shutterfinger · Dec 10, 2017

Excellent! Happy shooting.

Marco Gilardetti · Dec 11, 2017

It will remain forever a mistery how it could happen that the groundglass sled sideways with one lens and not with the other, but now let's forget about it. I'm very glad that the issue is fixed and that your beloved camera is reliable again. Enjoy!

itsdoable · Dec 11, 2017

One of your lenses is decentered differently from the other....

Tor-Einar Jarnbjo · Dec 11, 2017

Marco Gilardetti said:
It will remain forever a mistery how it could happen that the groundglass sled sideways with one lens and not with the other, but now let's forget about it. I'm very glad that the issue is fixed and that your beloved camera is reliable again. Enjoy!

'Sliding groundglass' is likely a secret terminology within the exorcist guild for a particular type of poltergeist.

I honestly tried to get a reasonable explanation for the behaviour from the service technician, but the French messieur just shook his head and mumbled something about 'quel malheur' and 'grande catastrophe'.

Tor-Einar Jarnbjo · Dec 11, 2017

itsdoable said:
One of your lenses is decentered differently from the other....

Based on what? The service technician checked all my lenses last week and found no issues with them.

shutterfinger · Dec 11, 2017

I did a google search for pentacon six service manual and found this https://kupdf.com/embed/pentacon-six-service-manual_58f6396ddc0d60e36fda983b.html?sp=0 but it won't download, go figure.
Screen capture for setting the mirror and image field lens:

I believe the image field lens is what the technician refereed to as the sliding ground glass.

Remember, do not strap the camera to a shock tower on your car then drive down a road full of pot holes, it will likely jar the optical system out of alignment.

moto-uno · Dec 11, 2017

^ Now for some photos ! Please, Regards,Peter

Tor-Einar Jarnbjo · Dec 12, 2017

moto-uno said:
^ Now for some photos ! Please, Regards,Peter

I'll spare you the boring focus test shots I did on Sunday evening.

I had done some outdoor photography on Saturday and Sunday as well, but didn't have time to develop the films until tonight. I now feel a dire need to bang my head against the wall or at least throw the camera from somewhere high. Yes, the focus is ok, but the shutter seems to fuck up again(!), likely due to cold weather. The entire roll of focus test shots I did indoor on Sunday evening were all exposed properly, but almost all the outdoor photos I made over the two days are blank, without even the faintest sign of exposure on the film. On a few exposures, it looks as if the shutter slit gets stuck and only exposes a narrow, vertical stripe on the film:

moto-uno · Dec 12, 2017

^ Wow , it never rains unless it pours , what a streak of rotten luck ! Peter

piu58 · Dec 15, 2017

> shutter seems to f**k up again(!), likely due to cold weather.
That is the reason I switched to a Kiev 60. Not a beauty, but much more reliable, especially in the cold.
I got always too long times if temperature was below around 5 deg C.

anfenglin · Dec 15, 2017

Hmm, I seem to be the only one with a fully functional P6.
I did a test in the cold lately, it works perfectly, apart from the slow speeds of course, but I don't use them anyway.

E. von Hoegh · Dec 15, 2017

Tor-Einar Jarnbjo said:
I'll spare you the boring focus test shots I did on Sunday evening.

I had done some outdoor photography on Saturday and Sunday as well, but didn't have time to develop the films until tonight. I now feel a dire need to bang my head against the wall or at least throw the camera from somewhere high. Yes, the focus is ok, but the shutter seems to fuck up again(!), likely due to cold weather. The entire roll of focus test shots I did indoor on Sunday evening were all exposed properly, but almost all the outdoor photos I made over the two days are blank, without even the faintest sign of exposure on the film. On a few exposures, it looks as if the shutter slit gets stuck and only exposes a narrow, vertical stripe on the film:

That's frustrating, to put it mildly.
It's -20c here this morning. While my recently overhauled cameras (synthetic oil, good to some abyssmally low temp.) will work ok, the fingers do not do so well.
I've found that the larger fp shutters, like yours, with relatively slow travelling curtains work well in cold conditions if properly lubricated, Moebius makes an "arctic" grade symthetic that I used in mine, it also can be used at normal -but not hot- ambient temps. Nye also makes a good cold weather oil.

moto-uno · Dec 31, 2017

^ I'm hoping the new year coming brings some better fortune ( and pics ) Regards,Peter

Tor-Einar Jarnbjo · Feb 25, 2018

It was not only the cold weather causing problems with the shutter. Last Saturday, eventually something broke completely, the camera made a distinct sound of 'something went wrong' when cocking the shutter and after that, the shutter refused to stay cocked. When releasing the transport lever, the shutter curtain simply spooled back into the resting position. Having had enough problems with the camera during the last year, I gave it up and got me a 'new' allegedly working Pentacon body. After running through two test rolls to check focus and shutter speeds, everything actually worked within reasonable expectations.

So, yesterday I went out to do some actual photos and after shooting six rolls and after developing them today, I have really bad light leaks on all images on the later rolls. Going through the camera, I find a rather large (about 2x3mm) hole in the shutter cloth. I have absolutely no idea have I managed to achieve that. Nevertheless, since some of you asked for images, here are a few of the better ones I manage to take before the new camera gave up too

shutterfinger · Feb 25, 2018

Sorry to hear you're having so much bad luck with your camera(s).
Open the camera (remove /open the back, remove the lens, lock the mirror up) so you can access both sides of the damaged curtain.
Cut a piece of fine weave black cloth to just fit the hole in the curtain.
Use some fabric seam glue along the edges of the hole and position the patch piece in.
Once cured paint over the patch with acrylic artist paint diluted 1:1 to 1:2 in 2 to 4 thin coats until light tight.

I do not know what products are available in your area so for reference
Beacon Fabri-Tac Premium Fabric Glue works very well http://www.joann.com/fabri-tac-permanent-adhesive-4-oz/2012003.html
Golden Heavy Body Artist paint #1040 Carbon black https://www.goldenpaints.com/products/colors/heavy-body

Pentacon Six & Biometar 80 focus problem

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