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01-25-2013, 02:09 AM   #1
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Adapter to go from M42 mount to Pentax k-mount lens

Greetings to all,

I am having a terrible time trying to understand what I need in order to go from an M42 screw mount (Pentax Spotmatic F camera) to a Pentax k-mount lens. Okay, when I search, I see the title of the product says," M42 to k-mount adapter." However, I see the adapter is threaded inside to accept a screw mount lens. This is really driving me crazy.

Please help.

Thanks,
Tony

01-25-2013, 02:27 AM   #2
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Tony, welcome to the forum.

The "M42 to K-mount adapter" is designed to put old screwmount lenses on newer K-mount (bayonet) cameras, including the DSLRs.
Trying to go the other way around, so putting a K-mount bayonet lens on a Spotmatic or other screwmount camera,
won't work for anything other than macro.
The screwmount is narrower than the K-mount bayonet, so there's no room to fit the lens in.

For macro, see the setup Stone G. mentions below.

Last edited by lytrytyr; 01-25-2013 at 04:14 AM.
01-25-2013, 02:27 AM   #3
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Hi Tony,

Unfortunately this won't work! A M42-lens to a K-mount camera is possible, but the other way around not....
The K-mount bayonet of the lens is too wide to fit in a M-42 body, so a imaginable adapter would have to mount the lens in front of the body, making focussing impossible....
01-25-2013, 03:57 AM   #4
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QuoteOriginally posted by Rense Quote
Hi Tony,

Unfortunately this won't work! A M42-lens to a K-mount camera is possible, but the other way around not....
The K-mount bayonet of the lens is too wide to fit in a M-42 body, so a imaginable adapter would have to mount the lens in front of the body, making focussing impossible....
At least it will never work for infinity focus. For shorter distances, one may constrct an adapter from slim M42 and PK extension tubes, but that's hardly what you are after.



01-25-2013, 11:57 AM   #5
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M42 mount configured to accept K-mount lens

Well, thank you very much for clearing it up. I just assumed that the terminology meant to go from a M42 to a k-mount was what I was looking for. Okay, live and learn.

Thanks again,

Tony
01-25-2013, 02:41 PM   #6
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QuoteOriginally posted by Tonytee Quote
Greetings to all,

I am having a terrible time trying to understand what I need in order to go from an M42 screw mount (Pentax Spotmatic F camera) to a Pentax k-mount lens. Okay, when I search, I see the title of the product says," M42 to k-mount adapter." However, I see the adapter is threaded inside to accept a screw mount lens. This is really driving me crazy.

Please help.

Thanks,
Tony
Hi Tony,
You do need an M42 to K mount adapter to mount an M42 lens to a K mount body. Just be sure that you get a genuine Pentax adapter as the after market ones can jam on your K mount body. The after market ones also do not always focus to infinity.
Regards.
01-25-2013, 10:16 PM   #7
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Hello Gordon,
Actually, what I need is just the opposite. I have a Pentax Spotmatic F SLR with a M42 screw mount. I need to convert the screw mount to a bayonet mount for my Pentax 50mm k-mount lens. I understand that this is just not possible.

Thanks very much for your contribution.
Tony
01-25-2013, 10:57 PM   #8
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QuoteOriginally posted by Tonytee Quote
Hello Gordon,
Actually, what I need is just the opposite. I have a Pentax Spotmatic F SLR with a M42 screw mount. I need to convert the screw mount to a bayonet mount for my Pentax 50mm k-mount lens. I understand that this is just not possible.

Thanks very much for your contribution.
Tony
I think you mean the opposite. You are trying to covert the K mount to fit the screw mount.

01-25-2013, 11:56 PM   #9
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Well, I guess I am not doing a very good job of explaining. I have a k-mount lens that I would like to fit onto an M42 screw mount. Anyway, what I need to do is not possible. So, at this juncture it is a moot point.

Thanks again,
Tony
01-26-2013, 04:00 PM   #10
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QuoteOriginally posted by Tonytee Quote
Well, I guess I am not doing a very good job of explaining. I have a k-mount lens that I would like to fit onto an M42 screw mount. Anyway, what I need to do is not possible. So, at this juncture it is a moot point.

Thanks again,
Tony
Yes it is impossible without getting severe image constriction. Regarding the clarity of the explanation of the issue the fundamental origin of the matter is whether the adapter is an accessory for the body (thereby being described as converting m42 to K) or an accessory for the lens (thereby converting K to m42). Both interpretations are possible.
.

Last edited by Arjay Bee; 01-26-2013 at 07:53 PM.
01-26-2013, 04:35 PM   #11
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Thanks Arjay, your input is greatly appreciated.

Keep on Pentaxing.

Adios,
Tony
01-26-2013, 08:49 PM   #12
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QuoteOriginally posted by Tonytee Quote
Well, I guess I am not doing a very good job of explaining. I have a k-mount lens that I would like to fit onto an M42 screw mount. Anyway, what I need to do is not possible. So, at this juncture it is a moot point.

Thanks again,
Tony
Hi Tony,
Adapters to fit an M42 to a K mount are readily available,but I am not aware of the reverse happening. In saying that, it does not mean that it is not possible.
Regards.
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