Conversion

Robert Stokes · 06-14-2009, 11:11 AM

I have a film version Pentax SLR with many lenses. If I buy a digital camera body, will I be able to use all these lenses?

and · 06-14-2009, 11:21 AM

Welcome to the forums!
Yes you will. the focal length of the lens will be multiplied 1.5 times

some articles
https://www.pentaxforums.com/forums/pentax-lens-articles/49442-pentax-k-mount...it-bodies.html
https://www.pentaxforums.com/forums/pentax-lens-articles/3800-can-i-use-m42-s...unt-d-slr.html

Mike Cash · 06-14-2009, 11:38 AM

Originally posted by Robert Stokes

I have a film version Pentax SLR with many lenses. If I buy a digital camera body, will I be able to use all these lenses?

Absolutely.

Notice that the beautiful thing about Pentax backwards compatibility is that we don't even have to ask you "Which film version Pentax and what lenses" in order to answer the question.

noblepa · 06-15-2009, 01:23 PM

Are your lenses k-mount (bayonet) or screw-mount? If the latter, you will need an adapter. If the former, they will mount directly on any Pentax dslr, with no adapter.

There are some limitations. Obviously, you will not have auto-focus with manual-focus lenses. Manual-focus lenses with the "A" setting will work the best. These will meter on a dslr just as they do on a film camera, including full-auto exposure control and shutter priority.

K-mount lenses without the "A" setting are a little more problematic. The Pentax dslrs lack the linkage to read the aperture setting on the mechanical lenses. You must focus, set the aperture and press the "Green" button to stop the lens down and take the meter reading.

M42 (screw-mount) lenses require an adapter and must be used in stop-down metering mode, even the SMC Takumars, that have the linkage for wide-open metering on the Spotmatic F, ES and ES-II.

I think its a little misleading to say that the focal length is multiplied by 1.5. The focal length stays the same. However, the smaller sensor of a dslr means that the field of view is narrower than it would be on a film SLR. The factor is 1.5 though, so the statement is true to that extent. For example, a 100mm lens on a dslr has the same field of view that a 150mm lens would have on a 35mm SLR. A 200mm lens has the fov-equivalent of a 300mm lens on a film slr.

Personally, I don't think about it any more. I simply learned a few new reference points. A "normal" lens is about 33mm on my K10D. A focal length less than that is a wide angle; longer than that is a telephoto.

Tom in Delaware · 06-15-2009, 05:30 PM

Because of the peculiarities of the digital sensor some lenses will cause a purple fringing that is not seen on film. This will show up around light or white objects. I have not seen this with the Takumar or Pentax-M lenses I have.

Ron Redwood · 06-22-2009, 10:26 AM

Originally posted by Mike Cash

Absolutely.

Notice that the beautiful thing about Pentax backwards compatibility is that we don't even have to ask you "Which film version Pentax and what lenses" in order to answer the question.

And with the anti-shake in the DSLR body...you even get benefit from that.

I have a 70's screw mt Mamiya,an 80's vintage Chinon (K mt) and a 90's Pentax...with some Sigma YS mt lenses ( K + M42 adapters) and several Tamrons (also M42 + screw adapt) I have some Pentax + Mamiya screw primes and a fast Soligor 35mm wide,a K mt Tak 100 macro, an AF Pentax mid zoom. MOST of which can be used in almost any mix of body + lens...and is all (somewhat) usable with a Pentax K10 or any Pentax.

06-14-2009, 11:11 AM	#1
Robert Stokes Inactive Account Join Date: Jun 2009 Location: Fort Lauderdale, FL 33308 Posts: 1	Conversion I have a film version Pentax SLR with many lenses. If I buy a digital camera body, will I be able to use all these lenses?

06-15-2009, 01:23 PM	#4
noblepa Veteran Member Join Date: Sep 2007 Location: Bay Village, Ohio USA Posts: 1,142	K-mount or screw-mount lenses? Are your lenses k-mount (bayonet) or screw-mount? If the latter, you will need an adapter. If the former, they will mount directly on any Pentax dslr, with no adapter. There are some limitations. Obviously, you will not have auto-focus with manual-focus lenses. Manual-focus lenses with the "A" setting will work the best. These will meter on a dslr just as they do on a film camera, including full-auto exposure control and shutter priority. K-mount lenses without the "A" setting are a little more problematic. The Pentax dslrs lack the linkage to read the aperture setting on the mechanical lenses. You must focus, set the aperture and press the "Green" button to stop the lens down and take the meter reading. M42 (screw-mount) lenses require an adapter and must be used in stop-down metering mode, even the SMC Takumars, that have the linkage for wide-open metering on the Spotmatic F, ES and ES-II. I think its a little misleading to say that the focal length is multiplied by 1.5. The focal length stays the same. However, the smaller sensor of a dslr means that the field of view is narrower than it would be on a film SLR. The factor is 1.5 though, so the statement is true to that extent. For example, a 100mm lens on a dslr has the same field of view that a 150mm lens would have on a 35mm SLR. A 200mm lens has the fov-equivalent of a 300mm lens on a film slr. Personally, I don't think about it any more. I simply learned a few new reference points. A "normal" lens is about 33mm on my K10D. A focal length less than that is a wide angle; longer than that is a telephoto.

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06-14-2009, 11:21 AM	#2
and Veteran Member Join Date: Mar 2007 Photos: Gallery Posts: 2,476	Welcome to the forums! Yes you will. the focal length of the lens will be multiplied 1.5 times some articles https://www.pentaxforums.com/forums/pentax-lens-articles/49442-pentax-k-mount...it-bodies.html https://www.pentaxforums.com/forums/pentax-lens-articles/3800-can-i-use-m42-s...unt-d-slr.html

06-14-2009, 11:38 AM	#3
Mike Cash Veteran Member Join Date: Jan 2007 Location: Japan Photos: Gallery Posts: 6,950	Originally posted by Robert Stokes I have a film version Pentax SLR with many lenses. If I buy a digital camera body, will I be able to use all these lenses? Absolutely. Notice that the beautiful thing about Pentax backwards compatibility is that we don't even have to ask you "Which film version Pentax and what lenses" in order to answer the question.

06-15-2009, 05:30 PM	#5
Tom in Delaware Senior Member Join Date: May 2009 Location: Delaware Posts: 177	Because of the peculiarities of the digital sensor some lenses will cause a purple fringing that is not seen on film. This will show up around light or white objects. I have not seen this with the Takumar or Pentax-M lenses I have.

06-22-2009, 10:26 AM	#6
Ron Redwood Inactive Account Join Date: Jun 2009 Location: Santa Cruz Mountains Posts: 53	Originally posted by Mike Cash Absolutely. Notice that the beautiful thing about Pentax backwards compatibility is that we don't even have to ask you "Which film version Pentax and what lenses" in order to answer the question. And with the anti-shake in the DSLR body...you even get benefit from that. I have a 70's screw mt Mamiya,an 80's vintage Chinon (K mt) and a 90's Pentax...with some Sigma YS mt lenses ( K + M42 adapters) and several Tamrons (also M42 + screw adapt) I have some Pentax + Mamiya screw primes and a fast Soligor 35mm wide,a K mt Tak 100 macro, an AF Pentax mid zoom. MOST of which can be used in almost any mix of body + lens...and is all (somewhat) usable with a Pentax K10 or any Pentax.