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12-15-2007, 02:27 PM   #1
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Dumb question:

I often see lenses like this one:

Pentax-A* SMC 645 600mm 5.6 ED Lens 645N NR 27759 - (eBay item 290191716292 end time Dec-24-07 18:39:09 PST)

Beautiful lenses designed for 645 or 67 systems that sell for a fraction of what the 35mm equiv. lenses do.

Is there not ANY way these can be adapted for use on a K100 or K10???

12-15-2007, 02:53 PM   #2
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There are no dumb questions - just dumb answers!

As far as my limited knowledge allows me it is entirely possible to put a 645 lens on a 35mm Pentax body if you use the proper adapter. Kind of like this.

A more detailed and intense search should produce cheaper examples of this adapter.

Another forum post on this subject is here.

Happy hunting!
12-15-2007, 02:57 PM   #3
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It can be done, but probably is not wothwhile.

The lenses, being made for medium format, are bigger and heavier than even their 35mm full-frame counterparts. Adapters are available, but expensive -- about $150, if I recall correctly. The crop factor for a 645 lens on an APS-C sensor is approximately 2.2, so that 600mm lens would effectively become a 1320mm.
12-15-2007, 03:12 PM   #4
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Being a medium format lens means it'll be very impressive quality as well.

12-15-2007, 03:22 PM   #5
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QuoteOriginally posted by little laker Quote
Being a medium format lens means it'll be very impressive quality as well.
why does everyone say that? MF lenses actually can be LOWER quality, because of the bigger image area...
12-15-2007, 04:13 PM   #6
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QuoteOriginally posted by little laker Quote
Being a medium format lens means it'll be very impressive quality as well.
Usually, a 35mm lens will resolve better than a medium format lens of equal quality. The lens designer of the medium format lens has to cover a huge image circle, and the compromises result in lower central resolution, and that is where the 35mm frame or APS-C sensor is getting its light from.
12-15-2007, 04:33 PM   #7
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QuoteOriginally posted by Canada_Rockies Quote
Usually, a 35mm lens will resolve better than a medium format lens of equal quality. The lens designer of the medium format lens has to cover a huge image circle, and the compromises result in lower central resolution, and that is where the 35mm frame or APS-C sensor is getting its light from.
Really? Are you sure or are you guessing? The larger image circle to cover the larger format is why medium format lenses are physically bigger and cost a lot more than 35mm lenses, plus the equivalent focal length compared to a 35mm lens is longer. I have owned and used the Pentax 645 & 67s, Bronicas and Hasselblads and the MF lenses resolve just as as good if not better than a lot of 35mm lenses.
12-15-2007, 07:45 PM   #8
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QuoteOriginally posted by little laker Quote
Being a medium format lens means it'll be very impressive quality as well.

Not necessarily. Crap can come in every size.

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