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09-10-2008, 11:31 AM   #16
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QuoteOriginally posted by Busiko Quote
Gooshin is right. As Platinium said when he presses the pin the diaphragm will operate correctly. Since he is using a genuine Pentax screw-K adapter, that pin is kept pushed permanently...
Not so.

The genuine Pentax adapter has no mechanism to depress the pin. That is why buyers of M-42 lenses should take care to check that lenses either have the auto/manual switch or are manual/preset diaphragm if they wish to mount on a K-mount camera. The same is true if the user wants to mount a lens on a non-auto M-42 bellows or extension tube.

Here is a link to more information and an interesting modification to the adapter

Steve


Last edited by stevebrot; 09-10-2008 at 11:38 AM.
09-10-2008, 12:10 PM   #17
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A very small droplet of epoxy can be removed easily with a pointed knife or simular item. Another idea is to hold down the pin and force a round tooth pick into the hole, then break off the excess. This will wedge against the pin and hold it in the depressed position. Regardless, the pin must be depressed to gain appeture control on your DSLR.

Dave

QuoteOriginally posted by platinum Quote
this is a good idea, but if then i want to remove epoxy?
it is possibile about your experience?
09-10-2008, 01:43 PM   #18
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I am very happy with my results shooting in manual and using the green button. What am i missing out on??
09-10-2008, 01:59 PM   #19
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QuoteOriginally posted by bruloup Quote
I am very happy with my results shooting in manual and using the green button. What am i missing out on??
It is a lot easier to use the Av mode with your Super-Taks. Here is the sequence:
  • Put the camera in Av mode
  • Make sure that the auto/manual slider on the lens is set to manual
  • Focus with the lens wide open
  • Stop down to whatever f-stop you desire. The camera will set the shutter speed.

Steve

09-10-2008, 02:21 PM   #20
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just tried it and the results seemed underexposed vs the manual green button way.. I am also on spot metering is that the problem?
09-10-2008, 02:33 PM   #21
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QuoteOriginally posted by bruloup Quote
just tried it and the results seemed underexposed vs the manual green button way.. I am also on spot metering is that the problem?
The exposure settings should be the same for Av vs. M using green button (assuming the aperture is set the same for either mode) since both are using the same mechanism.

Steve
09-10-2008, 03:53 PM   #22
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sorry, but is there an m42 adapter pressing the pin?

i found this
http://cgi.ebay.it/ADAPTER-M42-Pentax-Zeiss-Pentacon-Zenit-SU-CANON-EOS_W0QQ...QQcmdZViewItem
but it is for Canon
09-10-2008, 04:20 PM   #23
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There is a very good thread on DPR on this very subject:

Manual focusing and metering: Pentax SLR Talk Forum: Digital Photography Review

09-10-2008, 08:18 PM   #24
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I scoured the Web this evening regarding fixes for the Zenitar-M 16/2.8 when used on a K-mount camera and came up almost empty handed. There was one article where the author removed the mount and added a cylindrical shim to the actuator pin such that it is always in the depressed position. (I think he used a thin plastic "coffee straw" cut to size for the shim.) When the mount is reassembled the the aperture becomes fully manual. The attraction to this approach is that it should be fully reversible.

Steve
09-10-2008, 09:46 PM   #25
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Damn! This thread makes my head hurt.
09-10-2008, 10:35 PM   #26
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QuoteOriginally posted by Blue Quote
Damn! This thread makes my head hurt.
Blame the Russians. They are the ones that built an M-42 lens with no auto/manual switch.

Steve
09-15-2008, 08:19 AM   #27
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QuoteOriginally posted by bruloup Quote
just tried it and the results seemed underexposed vs the manual green button way.. I am also on spot metering is that the problem?
Don't worry ... I have the same issues ... so i just stick with M and Green button ... works every time ... whereas AV mode underexposes on my K10D. I jsut stick with M-mode.

Dave ... thanks for the good info regarding the epoxy for the aperture pin ... I will keep that in mind if i come across this problem.
09-16-2008, 11:08 PM   #28
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QuoteOriginally posted by Big Dave Quote
A very small droplet of epoxy can be removed easily with a pointed knife or simular item. Another idea is to hold down the pin and force a round tooth pick into the hole, then break off the excess. This will wedge against the pin and hold it in the depressed position. Regardless, the pin must be depressed to gain appeture control on your DSLR.

Dave
Dave ... is this a problem for M42 versions only?????
I just picked up a K-mount Zenitar today .. and it works a charm when it comes to selecting the correct SS for the Aperture I dial in.
09-18-2008, 12:32 PM   #29
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Mechan,
The k-mount lens appeture is controlled by the DSLR body. The DSLR isn't setup to control the M42 appeture, so the lens must either be placed in manual mode with a switch on the lens or the pin must be held in the depress position. Otherwise the lens won't respond to the appeture setting and will stay wide open.

Dave






QuoteOriginally posted by Mechan1k Quote
Dave ... is this a problem for M42 versions only?????
I just picked up a K-mount Zenitar today .. and it works a charm when it comes to selecting the correct SS for the Aperture I dial in.
09-20-2008, 02:24 AM   #30
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That's what I thought ... as I know my M42 lenses have the pin on them ... but also have the Manual/Auto switch (which i leave on Manual) ... good to know ... so far so good with the Zenitar ... now to get use to shooting F/E style
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