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03-23-2012, 04:56 AM   #1
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Question about Pentax 50mm f1.4

Hello everyone.
I'm very new to this forum so my apology if I'm posting this question in the wrong section.

I have a Cosina C1s film camera that uses Pentax K mount. I'm going to buy a 50mm f1.4 for my film camera but the problem is everywhere I search, there are two lenses: "Pentax SMC 50mm f1.4" and "Pentax M SMC 50mm 1.4".

I'd like to know what is the difference between these two lenses and what does that letter "m" means.

I have no auto-focus, no auto-exposure, no auto-anything (), everything is manual. Which lens is better for me if I only care about quality?

03-23-2012, 08:19 AM - 1 Like   #2
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The "M" series was introduced after the original series of K-mount lenses; mostly they are smaller and lighter. Some say this is at the expense of quality, but that,s really more a question of the individual lenses - there are M series lenses that are definitely improvements on the lenses that came before. For more on the specific lenses, see the reviews you can find in the Lenses section of this site (see menu at top of this page). The non-M lenses are referred to as the "K" series in these reviews and in most discussions here. The later "A" series is mostly identical optically to the "M" series but suppors auto exposure, so they tend to be more expensive (higher demand). They will work fine on your camera if you happen to stimble upon an "A" version, but you'd be paying more for a capability you can't use.
03-23-2012, 08:40 AM - 1 Like   #3
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I recently did some comparisons between the K and M versions of this lens. For my copies at least, the K has a warm cast whereas the M is quite neutral in color. The K seems to have slightly better contrast. In most other optical respects they seem very similar. Build quality of both lenses is superb. The M version is much more common and with searching you can usually find one for cheaper than the K version. As Marc says, the optical formula is essentially identical in each of these. The K version takes a 52mm filter while the M version takes a 49mm filter.

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