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07-04-2007, 03:48 PM   #1
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What does the acronym DA actually stand for ?

Sorry as a newcomer to the Pentax forum, but what does the acronym DA on the lens actually stand for ? If I understand correctly, DA lenses are optimised specifically for use with APS-C sensor bodies, but I'd simply like to what DA is short for ? Digitally A............. (Anonymous) perhaps !

07-04-2007, 03:51 PM   #2
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My guess?

Digital Automatic, since there's no user input on the lens. It's all done by the camera body.
07-05-2007, 04:19 AM   #3
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What FireMate said makes sense, however I think this is a case of it simply not mattering.
07-05-2007, 05:09 AM   #4
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Digital Auto -- The acronym "A" has been added in the early 80s to indicate "Auto" aperture mode ("A" position on Pentax-A lenses). With a second generation of auto-focus lenses it became "FA" (replacing "F" series), then when they dropped aperture ring it became "FA J". Later on they put back aperture ring and optimized FA lenses for digital bodies (apparently with improved back element coating) naming them "D FA", and finally there came "DA" (for digital only with auto aperture control).

All in all -- it does not really matter :-)

07-05-2007, 07:12 AM   #5
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QuoteOriginally posted by Confused Quote
Sorry as a newcomer to the Pentax forum, but what does the acronym DA on the lens actually stand for ? If I understand correctly, DA lenses are optimised specifically for use with APS-C sensor bodies, but I'd simply like to what DA is short for ? Digitally A............. (Anonymous) perhaps !
So, we would look back Pentax's history for the old lens generations' naming:

K - K-mount lenses where K=King (looks at Asahi Pentax's old symbol, it is an eye with an crown with the K in it)

A - Auto aperture lenses

M - Manual aperture lenses - no big difference from K but needed to distinguish between the A lenses after/when they were lauched

AF - Auto Focusing lens - the only one in ME-F

F - New line of Auto Focus lenses, no AF motor in lens, body driven AF

FA - Advanced version of the F, enhanced and improved and contains more lens information and supposed to be more precise

DA - Digital lenses, the A is meaningless here and it was just made to match with the FA naming

For more read, see:-

K Mount Metering & Exposure Bases - A Technical Brief
07-05-2007, 07:43 AM   #6
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Digital (Image) Analysis

I believe it refers to Digital Image Analysis and the "I" was dropped to stay with previous naming conventions . . . if you really want to explore the subject, you could refer to the following book . . .

Remote Sensing Digital Image Analysis: An Introduction by Richards & Jia.

Paul
07-05-2007, 03:31 PM   #7
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"Don't Ask"? In spite of what the other brands' shooters might think, it does NOT stand for Dumb A**!
07-05-2007, 04:40 PM   #8
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One correction

QuoteOriginally posted by RiceHigh Quote
A - Auto aperture lenses

M - Manual aperture lenses - no big difference from K but needed to distinguish between the A lenses after/when they were lauched
Not quite: "M" has been introduced before "A". "M" signifies "Mini" or "Miniaturized" to highlight improvements in optical design resulting in same lens speed while allowing for much smaller and lighter lenses. Most notable example is the difference between K28/2 and M28/2:



K28/2 (left) vs M28/2 (right)
(Images from Bojidar Dimitrov's Pentax K-Mount Equipment Page)

However, to complete the "M" lineup some "K" lenses were simply released in "M" mechanical design with the same optical design. For example, K50/1.4 and M50/1.4 are optically identical, so "M" does not necessarily mean "smaller than K" in all cases. If lenses were already compact they just got "M shell" and that was all.

Interestingly enough, K24/2.8 had been released in 1977 after MX and ME bodies were introduced but despite the fact that optical design was in fact "miniaturized" and the lens barrel reads "smc PENTAX 1:2.8 24mm" typical for "M" lenses (not "SMC PENTAX 1:2.8/24" as on "K" lenses) the lens does not bear "M" designation! So K24/2.8 should have been M24/2.8 but for some reason there is no "M" suffix. (There are several more examples of this naming "anomaly".)

BTW, I feel a bit like a hard-core "Pentax historian" right now! :-)

QuoteQuote:
DA - Digital lenses, the A is meaningless here and it was just made to match with the FA naming
True, I could not agree more with this. Inherited "A" letter indicating "auto aperture" is not necessary here: since there is no aperture ring to set or not to set the "A" mode what else it could be than "auto aperture"? However, just "D" would look a bit cheesy, so I read DA as "Digital Auto everything (focus + aperture)". Still better than "DA J" I guess!!!

07-05-2007, 04:47 PM   #9
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QuoteOriginally posted by RiceHigh Quote
FA - Advanced version of the F, enhanced and improved and contains more lens information and supposed to be more precise

True:

FA stands for 'Fully Automatic'. I read it in some Pentax publication somewhere.


Not true:
DA stands for 'Death of the Aperture ring'.
07-06-2007, 04:05 AM   #10
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QuoteOriginally posted by carpents Quote

True:

FA stands for 'Fully Automatic'. I read it in some Pentax publication somewhere.
That seems to be another sensible explanation as the original FA lenses were intended to be with auto power zoom function. But then later on with the total failure of the power zoom lenses (simply very few people were interested in them), the later FA lenses made are of manual zoom only. So, this left alone the more advanced electronics in it but no big differences against the F lenses.

QuoteQuote:
Not true:
DA stands for 'Death of the Aperture ring'.
Well put, Carpents, you're my hero! ;-)
07-06-2007, 05:43 AM   #11
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I'd just like to say a very big thankyou to everybody who contributed towards replying to my original enquiry. It would be difficult to imagine a more knowledgable and friendly worldwide user-base from whom to seek an informed answer to my query, so many thanks once again for all your assistance.

Last edited by Confused; 07-06-2007 at 09:31 AM.
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