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04-18-2009, 02:02 PM   #1
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645 adapter puzzle

This morning a friend and I tried to shoot his K20D using a Pentax 645 to 35 mm adapter on my 645 600 f5.6 A* tele lens. We were unable to find a setting that would allow the camera to fire although we could clearly see the image through the viewfinder.

Anyone with guidance and/or experience with a modern digital on the 645 lenses via adapter?

Don

04-18-2009, 02:09 PM   #2
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Did you set the focusing to manual?
04-18-2009, 02:55 PM   #3
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QuoteOriginally posted by Andi Lo Quote
Did you set the focusing to manual?
Thanks for the response.

Yes, we had virtually all the settings at manual.

It is likely something obvious as you have indicated, but we were unable to find it.

The adapter appears to have aperture stop down capability, but not clear how it gets the exposure info. On manual we were unable to adjust the aperture or the shutter speed. Need some changed interactions or over ride?

Don
04-18-2009, 04:21 PM   #4
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This sounds suspiciously like a case of Custom Setting no. 36, "Using aperture ring" which by default is set to "Prohibited." If your friend has only used modern auto-focus auto-everything lenses in the past, that setting makes no difference and you'd never notice.

But for older K-mount lenses, and pretty much any lens that requires an adapter, you'll need to set it to "Permitted."

You can make that setting change and leave it there. I don't know why it's deactivated in the first place, and it won't affect usage with modern lenses (as long as the aperture ring, if there is one, remains set at "A").

04-18-2009, 07:21 PM   #5
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QuoteOriginally posted by pdstromberg Quote
The adapter appears to have aperture stop down capability, but not clear how it gets the exposure info.
Don
Just like the above post, go to Menu and enable aperture ring to use older manual lenses. One question though, I'm wondering what adapter you got as mine is all manual (no electrical contacts), so I have to use the aper. ring on the lens to stop down.
04-18-2009, 08:28 PM   #6
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Thanks for the info

I'm the friend, ltdstar. I appreciate the help. There's no reference in the K20D manual index for this info.
04-19-2009, 04:04 AM   #7
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QuoteOriginally posted by mysticcowboy Quote
I'm the friend, ltdstar. I appreciate the help. There's no reference in the K20D manual index for this info.
No, there is no Index entry. But you'll find it in the Contents as a singled out entry: "Appendix Notes on 36. Aperture Ring"

But this not clear to a first time manual lens user.

Ben
04-19-2009, 08:15 PM   #8
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The manual discuss Aperture Ring on page 251. You can enable it by pressing the Menu, then move over to the Custom Menu, then press the up arrow to go to option 36. and press the right arrow then select enable it. Hope it helps.

04-21-2009, 11:53 PM   #9
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Itdstar,
Missed your earlier question regarding the adapter. It is a standard Pentax labeled adapter ordered from B&H. There are no electrical contacts. Not yet confirmed that it will stop down by shooting any images, but the mechanics appear the same as on my manual 645A lenses.

pttdds
04-22-2009, 10:36 AM   #10
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I'm a little confused because I understood the description on the Pentax adaptor as stating it allows only stop-down metering. Does it really have a pass-thru type aperture coupling lever of some kind? Sorry folks but I haven't seen one up close.

My first thought on the noted problem was the F5.6 lens on the adaptor may not be passing enough light to the camera for the meter to operate. In full Manual it shouldn't matter though. I've thought of buying one of the Pentax 645-to-K adaptors so I'm curious myself.
04-22-2009, 10:51 AM   #11
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B Grace,
Well, when all else fails the instructions can be helpful. I just read the instructions with the adapter. It says explicitly that I am interpreting incorrectly. It does not auto stop down even when set at "A". That also implies stop down metering, but until actually using the adapter I won't know.

Sorry about the confusion.

Now I'm on to trying to find an adapter that will allow using some of my high end Sony/Zeiss lenses on the Pentax body. If they exist, I may get a Pentax body like the K20D. Have used Pentax cameras for a long time. Would be fun to be able to continue.

Anyone know of a Sony alpha lens adapter for the Pentax K bodies?

PTTDDS
04-22-2009, 12:07 PM   #12
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QuoteOriginally posted by pdstromberg Quote
Anyone know of a Sony alpha lens adapter for the Pentax K bodies?
A simple mechanical adapter is not possible, as the flange distance of the SOny/Minolta AF mount is one full mm shorter than the Pentax flange distance. Add to that the necessary thickness of the adapter itself and its clear you couldn't focus anywhere near infinity. SO you would need an adapter with a corrective lens and these would compromise the quality of your lenses, which makes the whole story somewhat pointless. Anyway, to my knowledge there is no such adapter on the market.

Ben
04-22-2009, 12:17 PM   #13
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QuoteQuote:
Anyone know of a Sony alpha lens adapter for the Pentax K bodies?

PTTDDS
Ben is correct about the adapter. But, there was a recent thread here with excellent directions on how to convert at least some Minolta lenses to K-Mount. Can anyone find the link?
04-22-2009, 12:24 PM   #14
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QuoteOriginally posted by Jewelltrail Quote
Ben is correct about the adapter. But, there was a recent thread here with excellent directions on how to convert at least some Minolta lenses to K-Mount. Can anyone find the link?
Ah, you're right, I remember that thread. But I guess pdstromberg might not be considering converting his "high end Zeiss/Sony lenses" to a fully manual PK-cripple. (Well, I wouldn't...)

Ben
04-22-2009, 12:27 PM   #15
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Ben,
Thanks. That explains not finding anything on any search. Guess I'll bag that option.

pttdds
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