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01-14-2011, 03:34 AM   #1
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AF speed: DA 40mm Limited vs DA 18-135 mm?

I am trying to choose my walk around system and can't decide..

I initially wanted 18-135 + 55-300 but then I thought I'd take DA 40mm instead of the new zoom since its IQ is much better and it does not obsolete 50-135 range on 55-300.

However one of the reasons I wanted 18-135 was AF speed with the new motor.

But I also heard that DA 40mm's AF speed is very good since it's so lightweight.

So can someone confirm it to me? Is DA 40 really good with AF and does it compete with new 18-135 motor?

01-14-2011, 05:50 AM   #2
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AF with DA 40mm is very fast, and since is a prime I suppose it will be faster than the AF of the 18-235mm.
01-14-2011, 06:42 AM   #3
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I haven't used the 18-135 (yet), although I've heard it is very quick in terms of AF. That said, the DA40 is among the fastest Pentax AF lenses I've every used and would be surprised if the 18-135 was actually faster.

Going back to your original post, I'm not sure I would worry too much about the overlap between the lenses. I personally don't mind significant overlap between zooms. The other question is if you bought the 40 instead of the 18-135, do you have anything to cover the wide end below 40mm?
01-14-2011, 07:38 AM   #4
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If there is a difference, it's likely small. The DA 40 is very fast but it's also about ergonomics and IQ. The DA 18-135 is a completely different experience. If you don't mind a slower lens, and need the flexibility, the 18-135 is fantastic.

01-14-2011, 09:35 AM   #5
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This all depends upon what you need in a "walk-around" setup. On my last vacation, I found I took half my shots with a K-x/DA40 and almost half the others with an Olympus XA2 (35mm on film). For a minimal-lens solution outdoors, I sometimes carried the kit lens+DA50-200, but interiors were mostly the DAltd15/21/40/70. If I had it to do now, I'd probably take the 18-135 as a one-lens solution along with the DAltds or DA12-24+ DA or VL 40.

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