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02-06-2019, 05:25 AM   #1
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Orestor 100/2,8 on Pentax KP

Hi everyone. Just today I received an Orestor 100 / 2.8, which I took deliberately for portraits and its bokeh. So of course I will use it at 90% at f / 2.8 ... but I noticed that it has a small button that, if I press it, closes the diaphragm to the chosen value, otherwise it remains always open. Well, I remember that on my helios 58 putting a piece of aluminum paper on the side of the contacts with the machine, he managed to close the diaphragm at the time of shooting. The same thing you think is possible also with the orestor?

02-06-2019, 05:46 AM   #2
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Which mount? I assume it is version 2 listed here: Meyer-Optik Görlitz Orestor 100 2.8 | Vintage Camera Lenses

If m42, there may be an adapter that can push in that button but I'm unfamiliar with the lens, and m42 isn't the only mount option the lens was offered in.
02-06-2019, 10:26 AM   #3
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I have the same lens albeit with a pentacon nameplate. This is the later version of the 100mm, and as you mention, it doesn't have the A-M switch of many M42 lenses, just a preview button. BTW this is a good overview of all this:

https://www.instructables.com/id/M42-Lens-Aperture-Control-on-Modern-DSLRs/

To get the lens to stop down with the aperture ring , you either need an M42 adapter that holds in the auto aperture pin on the base of the mount like this one, (see my review) or you need to "mod" the lens so that the pin is held in, normally this requires removing the mount (though some have simply glued it but I don't recommend that).
02-07-2019, 05:14 AM   #4
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See the mod below I did to a tamron adaptall M42 adaptor



All it needs is a small tube, about 2.5-3mm long between the mount and the internal apature mechanism.

My zenit 16mm fisheye is the same.

I use a section of a ballpoint pen refil. Put a slice on one side down the length, press the aperture pin down, and then slip the tube over the pin

Works like a charm


Last edited by Lowell Goudge; 02-07-2019 at 05:20 AM.
02-11-2019, 05:38 AM   #5
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QuoteOriginally posted by marcusBMG Quote
I have the same lens albeit with a pentacon nameplate. This is the later version of the 100mm, and as you mention, it doesn't have the A-M switch of many M42 lenses, just a preview button. BTW this is a good overview of all this:

https://www.instructables.com/id/M42-Lens-Aperture-Control-on-Modern-DSLRs/

To get the lens to stop down with the aperture ring , you either need an M42 adapter that holds in the auto aperture pin on the base of the mount like this one, (see my review) or you need to "mod" the lens so that the pin is held in, normally this requires removing the mount (though some have simply glued it but I don't recommend that).
Thanks very much!! This M42 to PK could be good to press pin? Kipon M42 Adapter auf Pentax K - NEU & OVP by Mediaresort | eBay
02-11-2019, 07:05 AM   #6
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That kipon is the same one I have. Overpriced IMO! Once I had attended to the rough edges mentioned in my review it has worked well.
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