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11-15-2008, 09:20 PM   #1
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DA vs FA primes on a K20D

I'll try to word this in a way that makes sense, but I'm wondering what the differences in optical quality and focus speed are between, say, a DA 40mm and FA 43mm or a DA 70mm and FA 77mm when used on the K20D. I realize the FAs can take great photos on a DSLR, but should one choose the DA versions of similar focal length primes instead because of their optimization for DSLRs? I'm not concerned so much about the extra cost of the FAs if they have better optics and speed on the K20D - I'll pay more for the better options. Hope this makes sense!

11-15-2008, 10:28 PM   #2
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Luckily, they're all great as far as I've seen.
The goal of the DA limiteds is a little different--they're much smaller and lighter, at the cost of speed. But resolution is excellent, auto-focus is very fast and there's quick-shift, where you can focus manually even when the camera is in auto-focus mode. This is the only thing I miss when using the FA limiteds.
The FA's are often considered a little more special in their rendering. They're no-compromise lenses. Faster, heavier and larger. People also just like to hold them.
On a K20D I don't think there'd be much of a difference in speed (I use the 21, 31 and 77 on my K10D and they all focus very fast).
11-15-2008, 11:04 PM   #3
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to elaborate more on farfisa's reponse on AF, the FA Limiteds are more designed to be Manually Focused Decently, and so they have a decent throw and some good "Feel"

in terms of resolution, the DA primes are sharper in the corners according to photozone
11-15-2008, 11:37 PM   #4
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re: Manual focusing--Totally, there's almost nothing to hold on the DA's for manual focus. Sadly, I don't have them all to compare, but the focus ring on the 77 turns almost 180 degrees, whereas the 21 turns less than 90 degrees.
A lot more play with the FA's in you're into manual. When I tried the 77 on my K100D, the autofocus felt slow, but I'm used to the K10D now...

11-16-2008, 02:35 PM   #5
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QuoteOriginally posted by enoxatnep Quote
I'm not concerned so much about the extra cost of the FAs if they have better optics and speed on the K20D - I'll pay more for the better options.
Be aware "speed" has two meanings here. You are apparently talking about focus speed, and the DA lenses generally win there. But most photographers use the term "speed" to refer to maximum aperture, not anything to do with focus. And FA lenses are definitely "faster" in the sense of larger maximum aperture.
11-16-2008, 08:33 PM   #6
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It's a good point you brought up about maximum aperture. I definitely like the idea of f1.8 on the FAs (I love the crazy-narrow DOF effects of lenses like these), and this leads me to wonder how these lenses fare wide open, i.e. the f1.8 of the FA primes vs. the f2.4/2.8 of the DA primes, in terms of bokeh, light falloff, etc?
11-16-2008, 08:49 PM   #7
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The differences are more subtle than you think. Even with higher aperture like f8, Fa limited tend to give the lifting feel to images which is rather unappreciated by many.

Da limited is microscopicly faster than Fa limited in general which I found little difference between the two catogories. However, Da limited tend to be more responsive with autofocus...

In terms of construction/build, fa limited are rather classic.
11-17-2008, 03:21 AM   #8
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QuoteOriginally posted by roentarre Quote
However, Da limited tend to be more responsive with autofocus...
I didn' make scientifc tests, but I got the feeling that the FA*300/4.5 has a faster AF than DA*300/4 (on a K20D). The FA*300/4.5 feels "instantaneous" to me, a feelng I get from no other lens ...

11-17-2008, 11:21 AM   #9
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QuoteOriginally posted by enoxatnep Quote
I'll try to word this in a way that makes sense, but I'm wondering what the differences in optical quality and focus speed are between, say, a DA 40mm and FA 43mm or a DA 70mm and FA 77mm when used on the K20D. I realize the FAs can take great photos on a DSLR, but should one choose the DA versions of similar focal length primes instead because of their optimization for DSLRs? I'm not concerned so much about the extra cost of the FAs if they have better optics and speed on the K20D - I'll pay more for the better options. Hope this makes sense!
I have 3 of the DA Limiteds, and I've read extensive reviews on all the Limiteds (and seen lots of samples), so this is what I've observed: The FAs are about a stop faster than the DAs, have better peak performance especially in the center, and slightly better bokeh. The DAs have a more harmonic performance across all F-stops, and so are sharper wide open and in the corners, but not quite as sharp as the FAs at optimum apertures. The FAs also seem to be more vulnerable to PF/CA, more so with the FA77 and less so with the FA31 (which is as close to optically perfect as perhaps any Pentax lens). If money was no object, the FA31 is a no-brainer on the K20D, and maybe the other two FA's as well. Since I actually own the DA Limiteds, you know I'm not being biased here!
11-17-2008, 12:18 PM   #10
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QuoteOriginally posted by falconeye Quote
I didn' make scientifc tests, but I got the feeling that the FA*300/4.5 has a faster AF than DA*300/4 (on a K20D). The FA*300/4.5 feels "instantaneous" to me, a feelng I get from no other lens ...
The DA* use SDM while the DA Limiteds use traditional AF
11-17-2008, 12:28 PM   #11
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While I do miss the larger apertures, I'm VERY happy with the DA limiteds. They're just tiny and light, and of course very good optics and build. It's just a joy to travel light.

It's also really cool being different, as everyone usually shows off having the bigger lens and all. Heck I show them how nice it is to go around with such tiny lenses and they're green with envy. You can't go everywhere with those L and 2.8 zooms. That's why I sold them all off for the DA limiteds.

Someday when I have more money to spend, maybe I'll get those DA*s again hehe.

For those times I need more speed/larger aperture, I use my 58/1.4 or the 35/2 I plan to purchase.

It's really a compromise.

DA LTD:
-really fast AF
-MF quickshift override
-smaller size
-lighter weight
-better price
-more even sharpness
-better CA and flare control

FA LTD:
-larger apertures
-better MF ring
-a bit sharper in the middle
-FF/35mm ready
-just friggin' lovely to hold and to be seen with
11-17-2008, 12:31 PM   #12
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QuoteOriginally posted by soccerjoe5 Quote
The DA* use SDM while the DA Limiteds use traditional AF
If it is primes that you are considering (which I believe you are) then the SDM difference will not be a factor...

Last edited by beaumont; 11-17-2008 at 12:45 PM.
11-18-2008, 04:10 AM   #13
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Manual focus on DA Ltds

Some of you guys complain about MF on DA Limiteds - short throw, etc.
I've got one question on that matter - is it the case with DA35 Macro as well? While it might not be a big problem with other Ltds, it would be nice to have decent manual focus on a macro lens.
11-18-2008, 05:14 AM   #14
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QuoteOriginally posted by ixian Quote
Some of you guys complain about MF on DA Limiteds - short throw, etc.
I've got one question on that matter - is it the case with DA35 Macro as well? While it might not be a big problem with other Ltds, it would be nice to have decent manual focus on a macro lens.

Oh no, that lens is a joy to use on MF.

I on the other hand have to problems using MF with the other DA Limiteds. They have a a light dampening on the focus rings, much nicer than the loose rubber focus rings on the other primes nowadays. It's just that the FA Limiteds are nicer.
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