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02-25-2009, 11:09 AM   #1
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The DA55 is about 3 times slower than the FA50!

Disclaimer: This is a test by a layman, who does not really know what he is doing.

Pentax DA55 and FA50 - a comparison

performed by blende8


Last edited by vitalsax; 02-25-2009 at 11:47 AM.
02-25-2009, 11:15 AM   #2
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QuoteOriginally posted by vitalsax Quote
Disclaimer: This is a test by a layman, who does not really know what he is doing.

Pentax DA55 and FA50 - a comparison

that's wieland's test that he talked about here
https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/51840-da55-fa50-my-results.html
02-25-2009, 11:20 AM   #3
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3 times slower is ridiculous at best. can he back that up with numbers?

QuoteQuote:
I am wondering why this is so and what Pentax has to say about it. Isn't it a confession of failure that an almost 20 year old lens focusses so much faster?
not this again.... refer to thread posted above. another joker who likely thinks SDM should be as fast as ring USM... and taking absolutely nothing other than its newer into consideration... they aren't the same lens, so why compare AF speed between the two anyway? makes no sense.

speaking strictly of the mechanics. the FA50 and the DA 55 are two completely different lenses. less glass elements in the FA. the FA is also smaller and lighter. (due to less glass, lack of on board motor, weather sealing, and the electronics associated with the auto/manual switch etc.) furthermore SDM does NOT equal faster focusing. I doubt it would be any faster if it was screw-driven compared to the FA. such ignorance.

Last edited by séamuis; 02-25-2009 at 11:28 AM.
02-25-2009, 11:36 AM   #4
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Notice in the very long thread comparing the DA*55 to the 43 Ltd that the bokeh has "issues" too (I'd link it if I knew how). In the image with the lenses and flash in the background, at f/1.4 the 55mm not only has circular highlights but they are double images also--ouch. Can't recall ever shooting wide open in 30 years, so the tests at 1.4 don't bother me much...

Sharpness and resolving power of the 55 is pretty impressive however...this should prove valuable for landscape type work with "everything in focus" from using tiny apertures. Haven't seen any tests at f/16 or f/22 to check diffraction issues--which are a major problem with digital systems when stopped down.

And what happens with the CA when stopped down? Does the fringing still occur? Sure like to know...

What's autofocus? Never heard of it...

I use the 43mm Ltd in this focal range class btw...

02-25-2009, 11:59 AM   #5
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I have no timed recordings to back this but I do have some experience with both lenses.

While the FA focused faster (I think it has a lot less throw in the focus ring), it's not as accurate as the DA*. My K20D with the FA in lower light (during studio shooting and in clubs) frequently failed to lock focus. I did a shoot last weekend and while the K20D/DA* combo sometimes hunted, it would usually lock almost instantly if I let up on the shutter release and half depressed it again. The FA, in similar circumstance, would simply whir-bump/whir-bump all over again and fail to lock.

I know it's subjective, but I think the AF system of my K20D functions better (meaning I actually achieve focus) with the DA* than it did with the FA 50mm in poor lighting conditions.
02-25-2009, 12:16 PM   #6
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At the end of the day, you're all still a bunch of measurebators. RiceHigh would be proud. :ugh:
02-25-2009, 12:19 PM   #7
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QuoteOriginally posted by ftpaddict Quote
At the end of the day, you're all still a bunch of measurebators. RiceHigh would be proud. :ugh:
ha. and I haven't used an AF lens since my 18-55mm kit lens.
02-25-2009, 01:33 PM   #8
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QuoteOriginally posted by séamuis Quote
ha. and I haven't used an AF lens since my 18-55mm kit lens.
Obviously you are not included in the above generalization.


also


Bravo!

02-25-2009, 01:39 PM   #9
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Am I the only one that is less than excited about SDM? I have it on my 50-135, and I am not thrilled. I wish I could get into the software to activate the screw drive.
02-25-2009, 01:43 PM   #10
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QuoteOriginally posted by ftpaddict Quote
At the end of the day, you're all still a bunch of measurebators. RiceHigh would be proud. :ugh:

Haha amateur photographer by day, armchair photographer by night.


Aside from all the time wasted arm-chairing and entertaining myself over 'redundant' camera tech info and Ken Rockwell's musings (as opposed to studying for my classes ), the awareness of tech/Camera UI/market trends have made me a chameleon for the photography masses ...at least in photography club I run. LoL. Although not the photo behemoth (my photos lack the wow factor) I'm able to help just about anyone that comes along with their camera issues. Wow I'm such a nerd.

I think some of the prevailing thoughts that the immaturity of the SDM system is the main cause for the AF issues arising out of these lenses could be on the right course although to really make a good conclusion, we'd need alot more experiments+observations. Not just the DA*'s but the DA17-70, variations in subject matter.

It could very well be the case that the SAFOX VIII(?) might be rather outdated or more importantly, the algorithms by which the camera makes assumptions/predictions of subject need to be rechecked. But remember that in the end, the camera is still a computer model making assumptions and its ultimately up to the photographer. Go for manual focus!
02-25-2009, 01:45 PM   #11
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QuoteOriginally posted by PentaxPoke Quote
Am I the only one that is less than excited about SDM? I have it on my 50-135, and I am not thrilled. I wish I could get into the software to activate the screw drive.
you would love it if it were ring type SDM not micromotor SDM.
02-25-2009, 01:46 PM   #12
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I just like not having to hear the screw drive, especially around other people.
02-25-2009, 01:48 PM   #13
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QuoteOriginally posted by séamuis Quote
you would love it if it were ring type SDM not micromotor SDM.
Is it a cost issue? Why is Pentax SDM micromotor instead of ring?
02-25-2009, 01:48 PM   #14
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QuoteOriginally posted by Votesh Quote
I just like not having to hear the screw drive, especially around other people.
which is exactly what the micromotor SDM is for. not faster AF.
02-25-2009, 01:57 PM   #15
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QuoteOriginally posted by PentaxPoke Quote
Is it a cost issue? Why is Pentax SDM micromotor instead of ring?

could be cost issue, maybe patent issue? I don't know. as I have stated before. the SDM employed in DA* lenses is the type of USM employed in the cheap canon USM lenses (think kit lens) just so they can say 'ultrasonic'. ring USM is completely different technology. I think of micromotor as a bit of a hybrid. has mechanical gears and uses 'ultrasonic' technology but doesnt use only 'ultrasonic' technology. but at the same time is more advanced than screw-drive.

micromotor is more or less going back to the type of AF lens that was used on the ME F. its all in the lens with only electrical contact between the body and lens. as oppossed to mechanical linkage between body and lens like that of screwdrive. its still (for the most part) mechanically driven just inside the lens. and of course more advanced motors. ring USM has no motors, and no mechanical linkage.
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