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02-13-2012, 08:21 PM   #1
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Two different versions of SMC Pentax-M 50mm f/2

I just got a second copy of the cheap SMC Pentax-M 50/2 lens, and discovered it does not have similarities to the first copy. Referred to, and found no information about the existence of the second version. So here we go.

Version 1:
- Weight: 164gr (measured);
- Aperture blades cross on the rear, counter-clockwise;
- Metal aperture control ring;
- "Asahi Opt. Co., Japan" on the front ring;
- Front lens group can be unscrewed after removing the name ring;
- Mostly metal internal construction;
- s/n 4,xxx,xxx

Version 2:
- Weight: 140gr (measured);
- Aperture blades cross on the front, clockwise;
- Plastic aperture control ring;
- "Asahi Optical Co." on the front ring, "made in Taiwan" engraved on a side of the barrel (only visible when lens is focused to MDF)
- Front lens group is retained with a brass ring and 3 screws;
- Mostly plastic internal construction;
- s/n 8,xxx,xxx

Apart from these changes, the rear glass element of the newer lens seems larger than that of an old lens. Its rear looks very different compared to both the older -M and the newer -A version, so it's unlikely that the newer 'A' glass has been simply fitted into the 'M' body.

I've never seen any sources pointing to the existence of v2 of this lens, but maybe this is one of the sources of reported 'sample variation' in this model.

02-13-2012, 08:31 PM   #2
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It's mentioned in the lens review section: SMC Pentax-M 50mm F2 Reviews - M Prime Lenses - Pentax Lens Reviews & Lens Database

I've had both, and they perform similarly, even if they aren't built the same.
02-13-2012, 09:48 PM   #3
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Original Poster
Ah, thank you - I missed that part completely!

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