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02-02-2010, 06:47 AM   #1
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What's the difference between K and M lenses?

Hi,

Sorry if this has been asked before, but I couldn't find any reference to it.
What's the difference between K and M lenses? And for that matter between F and FA?
I'm compiling a quick reference guide for lenses and I'd like to make sure I got it right.

K: original bayonet mount. Fully manual
A: Aperture automation capability
M: Fully manual *???????
F: First generation autofocus
FA: ????
DA: digital only lens (APS-C) will not work properly on full frame 35mm
*: The * after the lens type (A*, DA*) represents a premium grade

Any help will be appreciated. This is for a local photo club and I'm the only pentaxian so far......

Thanks,

02-02-2010, 06:53 AM   #2
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Rather than reinventing the wheel, take a look at Bojidar Dimitrov's excellent reference website for Pentax gear:
Summary of the K-Mount Evolution, Names, and Features
02-02-2010, 06:56 AM   #3
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Thanks!
That is exactly what I was trying to find!

Regards,
02-02-2010, 06:58 AM   #4
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In layman's terms:

M42: first kinds of lenses Pentax produced, for old screwmount bodies such as the Spotmatic; they can be adapted to all K-mount cameras

K: first bayonet series, no actual "K" markings

M: second bayonet series, some say the "M" marking stands for "mini" as most comparable lenses are smaller than their K counterparts

A: in general, K- or M-series lenses updated with auto-aperture contacts, and sometimes worse build quality

F: first foray into AF lenses

FA: second foray, mostly just physical re-designs of F lenses, but also some new ones (I think)

DA: third line of AF lenses, usually deigned for APS-C sized sensors only (but NOT always)

*: higher build or optics quality for older lenses (before Limiteds were introduced)

Ltd.: Limited lens, arguably the highest-build-quality among lenses Pentax has made, very compact lenses for their focal length, and highly superior image quality to comparable lenses

02-02-2010, 06:58 AM   #5
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A little late, but hey, someone may like it.
02-02-2010, 07:43 AM   #6
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QuoteOriginally posted by ismaelg Quote
Hi,

Sorry if this has been asked before, but I couldn't find any reference to it.
What's the difference between K and M lenses? And for that matter between F and FA?
I'm compiling a quick reference guide for lenses and I'd like to make sure I got it right.

K: original bayonet mount. Fully manual
A: Aperture automation capability
M: Fully manual *???????
F: First generation autofocus
FA: ????
DA: digital only lens (APS-C) will not work properly on full frame 35mm
*: The * after the lens type (A*, DA*) represents a premium grade

Any help will be appreciated. This is for a local photo club and I'm the only pentaxian so far......

Thanks,
the real difference between K and M is that the M series attempted to retain most lenses with a 49mm filter, and be very compact. The idea was to keep 49mm filters as a standard to help the photographer in reducing the number of filters. WHile this did not impact some lenses, others disappeared or changed.

in the M series, there was no 50mm F1.2, the 85mm went from F1.8 to F2, the 135mm F2.5 was dropped, the 200mm F2.5 I think got dropped and only a 200mm F4.

Additionally I think many of the wide angle lenses went to F3.5 as opposed to F2 or F2.8, but I am not really sure.

There were some improvements, however, specifically in the 300F4 which was downsized a little, and the 400F5.6 which became auto aperture as opposed to preset.

While some people consider the K mounts as re-packaged SMC Taks some were much better optically.
02-02-2010, 07:58 AM   #7
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Hey I have my Pentax 50mm f1.2 here I got it yesrerday. I thought it was f1.4 but yesterday I looked and surprised f1.2. I think it is rare??
02-02-2010, 08:05 AM   #8
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QuoteOriginally posted by Danny Delcambre Quote
Hey I have my Pentax 50mm f1.2 here I got it yesrerday. I thought it was f1.4 but yesterday I looked and surprised f1.2. I think it is rare??
lol........

02-02-2010, 08:17 AM   #9
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I mean Pentax M 50mm f1.2. Smile
02-02-2010, 08:28 AM   #10
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QuoteOriginally posted by Danny Delcambre Quote
Hey I have my Pentax 50mm f1.2 here I got it yesrerday. I thought it was f1.4 but yesterday I looked and surprised f1.2. I think it is rare??
Well if you got it for the price of a manual f1.4 you've done a good deal. You've probably noticed it's a great chunk of metal and glass - I find focusing with that low-geared ring rather slow but it means you can be very accurate. I just did some comparisons with an M50 1.7 - although centre sharpness seems pretty similar at the same apertures, away from the centre the 1.2 won easily. (Although I understand that with blurry-bokeh stuff edge sharpness is irrelevant.) Just stop down half a stop and you get a wonderful tool for low-light conditions.

But I am not sure I will carry it around routinely - I like the lightness of the M50, just as I like the lightness of the M100 2.8 vs the K105 2.8. They all take great pics though.

Tim
02-02-2010, 08:40 AM   #11
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QuoteOriginally posted by Danny Delcambre Quote
I mean Pentax M 50mm f1.2. Smile
No you didn't, no such thing
02-02-2010, 08:42 AM   #12
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QuoteOriginally posted by Danny Delcambre Quote
I mean Pentax M 50mm f1.2. Smile
there's no M50 1.2. if you got it for 25 bucks or less, then it's nothing more than an M 501:2, which is slower than an M 50 1.4. if you would look at the aperture ring, the aperture number starts at 2 followed by 2.8. a 1.2 lens starts at 1.2 followed by 2. look if the 1.2 is missing in the aperture ring.

always take a closer look at the difference. it can really be tricky for some who haven't encountered a 1.2 lens just yet.

50 1:2
50 1.2

1.2's only come in 2 types, the "K" and "A". no "M" version.
02-02-2010, 08:46 AM   #13
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QuoteOriginally posted by wallyb Quote
No you didn't, no such thing
What a let-down - I was quite excited for him.
02-02-2010, 08:53 AM   #14
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QuoteOriginally posted by timo Quote
What a let-down - I was quite excited for him.
it's quite easy nowadays to determine if someone mistook a 1.2 lens for a 1:2. it's not that unusual that one would get excited especially if it is priced around below 100 bucks or somewhere near the price of a manual focus 1.4 lens. it happens more often for non-owners.

the price alone would tell you that it's not, let alone the "M" marking.
02-02-2010, 02:04 PM   #15
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I have a different view :

QuoteOriginally posted by Lowell Goudge Quote
the real difference between K and M is that the M series attempted to retain most lenses with a 49mm filter, and be very compact. The idea was to keep 49mm filters as a standard to help the photographer in reducing the number of filters. WHile this did not impact some lenses, others disappeared or changed.
No, for mysterious reasons, the first generation K mount lenses got a 52mm filter thread, although a lot of them are rebadged SMC takumars (and these had 49mm as standard).

QuoteQuote:

in the M series, there was no 50mm F1.2, the 85mm went from F1.8 to F2, the 135mm F2.5 was dropped, the 200mm F2.5 I think got dropped and only a 200mm F4.
Th 135/2.5 was never replaced by a M version, and dropped when the M series was dropped for the A series. Same for the 200/2.5

QuoteQuote:

Additionally I think many of the wide angle lenses went to F3.5 as opposed to F2 or F2.8, but I am not really sure.
like the M 28mm/2.8 , or the M 35mm/2.8 ?

QuoteQuote:
There were some improvements, however, specifically in the 300F4 which was downsized a little, and the 400F5.6 which became auto aperture as opposed to preset.

While some people consider the K mounts as re-packaged SMC Taks some were much better optically.
Can you give examples of first generation K lenses which are optically much better than its SMC predecessor ?
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