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02-15-2007, 08:53 PM   #1
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2 Lens Questions

1. Is there a dedicated M42 thread in here? Maybe I'm just not searching properly. Are there any infinity focus issues with the M42 to K-Mount adaptors?

2. I have 5 Pentax 645 MF lenses kicking around, when I get a K10D will these be useful or not worth it? They are nice looking primes.

02-15-2007, 09:18 PM   #2
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QuoteOriginally posted by Timbuctoo Quote
1. Is there a dedicated M42 thread in here? Maybe I'm just not searching properly. Are there any infinity focus issues with the M42 to K-Mount adaptors?

2. I have 5 Pentax 645 MF lenses kicking around, when I get a K10D will these be useful or not worth it? They are nice looking primes.
You posted in the right spot.

A few people will probably mention this. Get the genuine Pentax screwmount to K adapter. It will save you a lot of heartache regarding any focus issues if you purchased a third party adapter which I've read about somewhere less than a couple days back.

Lots of guys will be able to toss in their two cents about the lenses you have. Just post up what you've got, and watch the feedback roll in when they all have a chance to read it.

Cheers!
02-15-2007, 09:33 PM   #3
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just did a film test shot w/ a super tak using an ebay bought screw to k adapter, no infinity focus
02-15-2007, 09:58 PM   #4
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There are at least two variation of screw to K mount adapters. The preferred version snaps into place and is flush to the cameras lens mounting plate. The less preferred mount snaps in and sits on top of the camera's mounting plate. this very small difference in distance of lens to film/sensor plane is the cause of 'no infinity focus' problems. a forum search for screw to K mount adapters should produce some actual photographs of the two adapters.

A big selling point for the new K series Pentax cameras is their compatibility with existing Pentax lenses-including the 645 lenses with the proper adapter. Knowing the actual focal lengths, maximum apertures and/or the lens name nomenclature will be necessary for anyone here to salivate with envy or advise you to dump them via a quick auction.

02-15-2007, 10:12 PM   #5
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Here are the Pentax 645 lenses I have: 35mm f3.5, 55mm f2.8, 75mm f2.8 & a nice 135mm f4. Are these any good and if they are good how much is the adaptor and where would I get one?

Will the 645 to K Mount adaptor make these lenses loose infinity focus and will the adaptor stuff up the lenses image quality? These lenses are rather large and built very well, they were passed on to me by the aerial photography unit when they could know longer fund a photographer so I got these for free!!
02-15-2007, 10:15 PM   #6
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shot of the tak with a screw to k adapter (ones you may find on ebay)



notice how it's protruding a bit



test shot with the takumar using an *ist film body
(bad film scan)
no post processing, bad film
slightly OOF

02-15-2007, 10:21 PM   #7
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So that M42 adaptor is the one that doesn't fit flush?? I haven't had much success with my M42 adapter on the 7D, I had to sand the face right back.
02-15-2007, 10:22 PM   #8
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QuoteOriginally posted by Timbuctoo Quote
Here are the Pentax 645 lenses I have: 35mm f3.5, 55mm f2.8, 75mm f2.8 & a nice 135mm f4. Are these any good and if they are good how much is the adaptor and where would I get one?

Will the 645 to K Mount adaptor make these lenses loose infinity focus and will the adaptor stuff up the lenses image quality? These lenses are rather large and built very well, they were passed on to me by the aerial photography unit when they could know longer fund a photographer so I got these for free!!
Lucky you, those lenses are great.

The Pentax Adapter K for 645 Lenses is what you're looking for. You maintain infinity focus but (of course) lose auto-aperture, so you use the lenses in stop-down mode.

As for finding one...eBay is the only place I've seen them - and even there rarely so. They're expensive, but given the amount you spent on the lenses, it is probably a fair deal.

--Sean

02-15-2007, 10:26 PM   #9
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QuoteOriginally posted by Timbuctoo Quote
So that M42 adaptor is the one that doesn't fit flush?? I haven't had much success with my M42 adapter on the 7D, I had to sand the face right back.
These are the M42 adapters for Pentax - the one on the left doesn't allow infinity focus because the flange sits 1mm higher than it should.


Note that the 'bad' one on the left should look exactly like the Minolta adapter - but it works on the Minolta because the M's register distance is 1mm shorter.
02-15-2007, 11:28 PM   #10
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How much is the Pentax one and are they found easily? Looks like I might need a couple of different one.
02-16-2007, 12:10 AM   #11
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There are always a couple of them on sale in ebay

The seller is usually the one based in Japan (645 to k mount). Price is usually around 45 to 150 US dollars. Depends on the sellers of course
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