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02-26-2010, 11:53 AM   #16
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QuoteOriginally posted by Marc Sabatella Quote
A useful if not entirely historically accurate assessment. Eg, "F" doesn't *really* stand for full frame, but that's the most relevant way to think about it these days - except that K, M, and A lens are *also* full frame. More problematic, "A" definitely does *not* mean autofocus - it means auto *exposure*.

Here's my quick summary:

A or F anywhere in the name = auto exposure
F or D anywhere in the name = auto focus
D but no F anywhere in the name = APS-C only (all others full frame or ASP-C)
no A, F, or D anywhere in the name = fully manual
Sorry, Marc. At this very moment, I'm holding the "smc PENTAX-FA INTERCHANGEABLE LENS operating manual". On page 3: "The Pentax FA lenses are primarily designed to work with the Pentax autofocus SLR (Kaf- or Kaf2-mount camera), making autofocus shooting possible." So, FA --> full-frame autofocus.

M-series lenses are indeed manual-aperture only. A-series lenses, and AFAIK everything newer, are auto-aperture, on supporting bodies. Same manual, page 4: "When using FA lens with the K-mount Pentax camera having no lens information contacts, be sure to set the lens aperture ring to any f-stop other than A." So, A doesn't always mean auto-aperture. Oy!

I'm also holding the DA Lens manual, and the "PENTAX 35mm INTERCHANGEABLE LENSES" manual that covers SMC Pentax-A lenses. In the latter, all 'A' references that I see are about auto-aperture, not auto-exposure. These are different. A fixed- or manual-aperture camera auto-exposes by auto-setting shutter speed.

Also [surging into FULL QUIBBLE MODE] I didn't say that ONLY 'F' refers to full-frame. Yes, M-series and A-series and K-mount and no-series Pentax lenses are also full-frame. [Sheesh, I just started that post to say that J means Junk.]

[/QUIBBLE]

02-26-2010, 09:38 PM   #17
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My list of what the lenses are on DSLR

  • K - a bayonet mount lens with no other qualifications: Manual Focus, Manual Exposure. Usable on any Pentax bayonet mount camera
  • M - as the K, but later, slightly smaller. I have two, and like them both.
  • A - Automatic aperture control with an aperture ring. Usable on any Pentax bayonet mount camera.
  • F - Auto focus lens, first series. It has the A on the aperture ring. Use with any bayonet Pentax camera
  • FA - Later version, somewhat better quality than the F series for me. Still has an aperture ring, so it is usable by any bayonet mount camera.
  • FA-J - not very highly considered. No aperture ring, so it cannot be used by the K1000 or KX or LX, etc. The camera must be able to control the aperture.
  • D-FA - Still film camera coverage, but digital coatings. No aperture ring.
  • DA - Not usable on film cameras because it cannot cover the whole negative, but some do work, some zooms at the longer focal lengths, but not at the shorter ones.
  • * - when added to the designation (on M lenses, A lenses, FA lenses and DA lenses) indicates "professional grade" supposedly.
  • Limited - very compact, very solid, very good lenses.
FWIW.
02-27-2010, 02:05 PM   #18
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QuoteOriginally posted by RioRico Quote
Sorry, Marc. At this very moment, I'm holding the "smc PENTAX-FA INTERCHANGEABLE LENS operating manual". On page 3: "The Pentax FA lenses are primarily designed to work with the Pentax autofocus SLR (Kaf- or Kaf2-mount camera), making autofocus shooting possible." So, FA --> full-frame autofocus.
Oh, absolutely - I never said F doesn't mean "full frame" in practice. Just that they didn't literally choose the letter "F" because of the word "full" or "frame", which one might otherwise ave inferred from what you wrote. Since the "F" series was the first autofocus lens, it seems obvious that the letter was chosen because of the word "focus". They didn't have a letter to indicate full frame, because *all* lenses were full frame at that time (well, I guess there were 110 and 645 format lenses too, but they were clearly identified as such).

QuoteQuote:
A-series lenses, and AFAIK everything newer, are auto-aperture, on supporting bodies. Same manual, page 4: "When using FA lens with the K-mount Pentax camera having no lens information contacts, be sure to set the lens aperture ring to any f-stop other than A." So, A doesn't always mean auto-aperture. Oy!
Good point. Although since all DSLR's support this, it's kind of an irrelevant distinction to most newbies.

QuoteQuote:
I'm also holding the DA Lens manual, and the "PENTAX 35mm INTERCHANGEABLE LENSES" manual that covers SMC Pentax-A lenses. In the latter, all 'A' references that I see are about auto-aperture, not auto-exposure. These are different. A fixed- or manual-aperture camera auto-exposes by auto-setting shutter speed.
Very good point. I tend to toss those terms around interchangeably, but it's not really accurate. Still, when talking about DSLR's or other "crippled"mount cameras, the distinction pretty much disappears, too - any lens that auto exposure is auto aperture, and vice versa.

QuoteQuote:
[Sheesh, I just started that post to say that J means Junk.]
Oh, and don't think I didn't notice that. I just didn't bother quibbling on that point, because i think I've probably made the same claim before :-)
02-27-2010, 05:32 PM   #19
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QuoteOriginally posted by Marc Sabatella Quote
Since the "F" series was the first autofocus lens, it seems obvious that the letter was chosen because of the word "focus". They didn't have a letter to indicate full frame, because *all* lenses were full frame at that time (well, I guess there were 110 and 645 format lenses too, but they were clearly identified as such).
Oops. I've never had a F-lens, don't have any documentation on them. I only write about what I know (or think I know). I haven't reached omniscience yet. Oh, F-word the F-lenses! I mean, the J-lenses! I mean... whatever... But now I wonder, will any Pentaxian here admit to owning at least one of each series of Asahi/Pentax lenses? Including the pre-M42 ones? Maybe that should be another thread. Maybe it already is. I'd better stop now.

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