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04-28-2011, 06:26 AM   #1
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Interesting phenomenon on Pentacon 4 200

Guys,

need some advise. Picked up a manual lens yesterday and noticed some "fog" on the pictures when I choose high aperture (11, 16, 22). Fully open until 8 the pictures are pretty well.

Lenses are clean and have no fungus etc.

Any comment or advise welcome.


f1:4.0


f1:5.6


f1:8.0


f1:11


f1:16


f1:22



and one picture with a very extreme effect:



Last edited by kheldour; 04-28-2011 at 06:33 AM.
04-28-2011, 07:04 AM   #2
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What do the aperture blades look like when stopped down (off camera)? Are they silvery instead of black? Do they (mostly) make a circle?
04-28-2011, 07:37 AM   #3
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this is interesting as there was a similar discussion regarding the Super Tak (8 element version) a few days ago, although the fogging was centrally located and tended to purple. The suspected cause was reflection somewhere off the diaphram, My copy as well as the OP for the thread both exhibited this, but note the situation improved with a longer hood and does not exist on flash, suggesting it is really an internal lens reflection due to light outside of the desired image circle entering the lens.

I have also seen things like this from reflections off shiny parts of the lens inside the mirror box on a Rikenon 135 F2.8 caused by a shinny black rear retaining ring on the rear element, and on a 645 lens due to shiny metal parts on the 645 to PK converter.

There have also been some reports of this being rear element reflection on a 100mmF2.8 macro when stopped down, But again centrally located and only at very small apertures.

I hope this helps/
04-28-2011, 11:15 AM   #4
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I dismantled the lens and removed all glass elements.

That's how the blades look like.

Rear side f22


Front view f22


Rear side f8



Front view f8



04-28-2011, 12:03 PM   #5
JVi
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I have the Pentacon 500/5.6 with a similar set up to yours. There is no indication of "flaring" at varying f-stops. If the aperture leaves look shiny, you may try using a dry graphite power lube applied carefully with a small brush. That will darken the iris leaves and lube them. You would want to "blow" out an residual powder before reassembling. See this link.

Last edited by JVi; 04-28-2011 at 12:12 PM.
04-29-2011, 11:53 AM   #6
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I have checked the lenses, aperture blades and the lens body itself again and couldn't find anything.

Then I did some more test photos and found some interesting outcome.
Shouting from INSIDE the building into outside didn't gave me a fog at all.

Shouting OUTSIDE and the fog was back again. Then I tried a longer lens hood - no effect. Even with almost 5" lens hood the flare/fog was still there and still at the same level.

Both pictures taken at f1:22

INSIDE to outside picture:


Outside picture:


Both at f1:22
04-29-2011, 12:02 PM   #7
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Can you put a UV filter on that lens?
Check out this discussion:
Filters - UV or not UV? - photo.net
I use Tiffen Haze-1's and 812's. Your problem has to be UV related since the image looks better behind glass.
04-29-2011, 12:08 PM   #8
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That is an interesting article, but usually the lens is not supposed to do that. And doesn't do that.

04-29-2011, 12:22 PM   #9
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The blades do look rather shiny in your photos. I can see how that could make it very susceptible to flare. Also, a 5" hood doesn't seem all that long for a 200mm lens on APS-C at f/22. I would try longer and/or narrower.
04-30-2011, 03:19 AM   #10
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Got the faulty part.

The M42-Connector has a too small bearing surface facing the M42-PK-adaptor. Therefore the small openings for the removal of the M42-PK-adaptor aren't covered and light can get into the mirrorhouse of the camera.

It is only a little amount of light getting through there, that is the reason, why you only can see it, when you close down the aperture.

I will either use insolation tape or fill the hole.

Last edited by kheldour; 04-30-2011 at 04:03 AM.
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