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01-03-2010, 02:42 AM   #16
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QuoteOriginally posted by Voe Quote
1. Of course, I meant both lenses at f/2.8.
1 =/= 2. I can't read your mind.

http://en.wikipedia.org/wiki/Dangling_modifier


Last edited by asdf; 01-03-2010 at 02:55 AM.
01-03-2010, 02:44 AM   #17
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QuoteOriginally posted by asdf Quote
Nope. DA* 16-50 is sharper *in the center* at f/2.8 than DA 31mm is at f/1.8 (the unfair comparison the original poster made).

Pentax SMC DA* 16-50mm f/2.8 ED [IF] SDM - Review / Test Report
Pentax SMC-FA 31mm f/1.8 AL Limited - Review / Test Report
interesting observation. Indeed those tests show that in theory the difference should be noticable for sure, even when extrapolating between 24-50mm in the DA in order to guesstimate the center sharpness at 31mm.

You sure can see there is a big swing in the other direction when stopping the 31ltd down to 2.8...but not matter the MTF (which are theoretical values to begin with, right? I might havea misunderstanding there so lemme know if I am missing some background. ) but to me the proof is always in the results and how a given copy of a lens matches up the the body being used.

If I were to go by the MTF tables only I probably would not buy a DA* 16-50 because of the wide variation over the zoom range...but when I see images taken at the various focal lengths and apertures, it's a damned fine lense. And even still, Voe's quite interesting shots aside, the 31ltd is even more impressive when I look at real shots taken. But what to I know since I am still doing battle with my 43ltd and 77ltd...some days they are my favoritests things in the world and other days,, well we bicker like an old married couple!! hehehehe....

nice thread, I look forward to those in the "know" sharing their experiences....but I aslo agree we need them there representative shots as that is were the data lies.
01-03-2010, 03:10 AM   #18
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QuoteOriginally posted by brecklundin Quote
If I were to go by the MTF tables only I probably would not buy a DA* 16-50 because of the wide variation over the zoom range...but when I see images taken at the various focal lengths and apertures, it's a damned fine lense.
From a practical standpoint, the main problem with this lens appears to be the reliability of the SDM motor and the scarcity of Pentax repair centers. In Canada, there is only one center qualified to fix these lenses.

Last edited by asdf; 01-03-2010 at 03:20 AM.
01-03-2010, 03:11 AM   #19
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QuoteOriginally posted by asdf Quote
I can't read your mind.
You don't have to, just don't assume.

01-03-2010, 03:16 AM   #20
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QuoteOriginally posted by Voe Quote
You don't have to, just don't assume.
You can try avoiding dangling modifiers.

You wrote "As the 31mm Limited is famous for being sharp even at f/1.8 it should be much better than the DA* 16-50mm at f/2.8."

"at f/2.8" follows "DA* 16-50mm."

"One morning I shot an elephant in my pajamas. How he got into my pajamas I'll never know." -- Groucho Marx
01-03-2010, 03:26 AM   #21
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With all due respect, you may take your "dangling modifiers" and put them you know where...

If you want to go down to stupid nit picking I never said that just because 31mm Limited is sharp even at f/1.8 it should be better than DA* 16-50mm when the former is at f/1.8 and the latter is at f/2.8, you just assumed it, thus my advice to you, don't assume. If you are not sure you can always ask nicely.
BTW, English is not my native language and I might not always express my self in the best possible way, so don't get too excited to pick on my grammar.
01-03-2010, 03:33 AM   #22
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QuoteOriginally posted by asdf Quote
From a practical standpoint, the main problem with this lens appears to be the reliability of the SDM motor and scarcity of Pentax repair centers. In Canada, there is only one center qualified to fix these lenses.
Bummer, I had no idea there was only one qualified service center in Canookia. No wonder I read people talking about glacially slow repair times. At least here in the US they have gone to CRIS as the main service center...I've had wonderful experience with them.

As for the 16-50 I researched the beastie a fair bit when I made my initial plunge into Pentax this past July or was it June? No matter, what stopped me from buying a copy was not just the SDM potential failure but more so it was the other build issues such as decentering and other things which should not sneak through. I really use this range a LOT it was supposed to replace the Sigma 24-60/2.8 I had with my 40D and was solid as a rock save zoom creep all copies seemed to eventually develop. But instead I grabbed a 50-135 which, suffered crib death of the SDM in the first 30-days. go figure, likely I over thought things... but I ended up with all primes to start in the 35ltd, 43ltd & 77ltd instead of either of the DA* zoom the 35ltd and the 77ltd.

Still, I am hoping we begin seeing less and less reported issues with the 16-50 or even better a newer updated version of SDM this year. If Pentax can shake that black cloud then the DA* are gonna be in my bag...until then I would rather buy the better primes which I never read of having and problems. And what keeps me out of the SDM camp is not only the fact my very first SDM lense failed almost out of the box, but that most reported failures are very soon after the warranty expires...something like that is more worrisome to me as eventually I expect modern zoom lenses with some sort of ultrasonic AF to need, at a minimum a good CLA experience and at worst a repair of the AF components after several years...but in under 2-yrs it seems to happen all to frequently.

But enough of me taking this thread OT...sorry about that...just found the discussion interesting.
01-03-2010, 03:35 AM   #23
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QuoteOriginally posted by asdf Quote
You can try avoiding dangling modifiers.

You wrote "As the 31mm Limited is famous for being sharp even at f/1.8 it should be much better than the DA* 16-50mm at f/2.8."

"at f/2.8" follows "DA* 16-50mm."

"One morning I shot an elephant in my pajamas. How he got into my pajamas I'll never know." -- Groucho Marx
who knew there was going to be a test? I was never told when I signed up for the class.

01-03-2010, 06:14 AM   #24
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If you really want to see a difference between the two lenses, try to take the same picture with both lenses, and put them in large (A3+) format prints. The difference won't be night and day, but you'll see a difference, especially around small details edge.
01-03-2010, 06:16 AM   #25
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QuoteOriginally posted by lawjbm Quote
ASDF and Ash:

Thanx so much for the replies. At the risk of sounding totally green--what is the point in having such an expensive lens (the 31) if it really is no better than the 16-50? Weight and size? If there is a difference at the edges I do not see it and I just took some pictures of my dog to see if I could see any appreciable difference. The fact that I had to go back and forth between the pictures over and over is telling.

I did try the Sigma 24 and was disappointed. Not a poor lens, but not a great one. I also tried the 18-55 WR as an inexpensive back up. About the same as the 24--not poor, only ok.

Anyway, I am just disappointed and was hoping I was missing something.

Thanx so much again for the quick replies.

Gregg
The FA31 is simply more than one full f-stop faster. And if you write, you virtually cannot distinguish images taken with the FA 31 at f/1.8 from those taken with the 16-50 at f/2.8, than this is testimonial to the high quality of the FA 31mm, in my opinion.

Ben
01-03-2010, 09:33 AM   #26
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Please post images. Impossible to advise on image quality without seeing it. The 16-50 should exhibit a lot more CA than the 31 and be softer on the edges, so make sure to include small tree branches against a bright sky in your comparative test.
01-03-2010, 10:51 AM   #27
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Hi all:

Thanx so much for all of the comments. I posted 4 photos. They are at:

Picasa Web Albums - gregg - Pentax

All were taken in manual with the same settings. One set is outdoors, one is inside. Same focus point for all. Of course, when I look at them now I do see some differences, but I would be curious to see if others think the differences are significant. All shot in RAW, processed identically, then saved to same settings as high quality JPEGs.

The slight blurry area on the left of the 16-50 running down the side in the outdoors shot is the side of my house.

Gregg

Last edited by candgpics; 01-03-2010 at 10:57 AM.
01-03-2010, 12:13 PM   #28
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Indoor shots are not very useful Gregg. Not enough detail to make any meaningful comparisons.
Outdoor shots - both sharp, but again not top resolution and not indicated which lens took which image.
There is CA in both images, a green shift in #1 at the snow-capped house in the centre and mild purple fringing at the branches above it, whilst #2 shows more of the blue/green shift in the high contrast areas throughout the image.
01-03-2010, 12:55 PM   #29
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QuoteOriginally posted by lawjbm Quote
Hi all:

Thanx so much for all of the comments. I posted 4 photos. They are at:

Picasa Web Albums - gregg - Pentax

All were taken in manual with the same settings. One set is outdoors, one is inside. Same focus point for all. Of course, when I look at them now I do see some differences, but I would be curious to see if others think the differences are significant. All shot in RAW, processed identically, then saved to same settings as high quality JPEGs.

The slight blurry area on the left of the 16-50 running down the side in the outdoors shot is the side of my house.

Gregg
Gregg, your images show just one thing: with a wider aperture the image gets brighter. You used the same shutter speed, but different apertures for the same shots. Also both images do not contain meaningful image data /washed out snow versus near monochrome indoor wall.) I don't think anybody can make a useful comment based on this.

So, what exactly is your problem with the FA 31? If you are personally satisfied with the DA 16-50, which is a fine lens, and see no need for the FA 31, despite its noticeably faster max aperture (which is also useful to limit depth of field), just sell it.

The finer differences between these two lenses (apart from the aperture advantage of the FA 31) are things like rendering of out of focus blur (bokeh) and colour rendering. Both of which boil down to personal preferences. These differences cannot be demonstrated with the example shots.

Ben
01-03-2010, 02:53 PM   #30
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Thanx Ash and Ben

Ash and Ben:

Thanx for the info. The EXIF info should be available in the Picasa post. Each pair had the same exact settings--same aperture, shutter speed, ISO, etc. Same settings in CS4 (my general default sharpening, clarity, etc).

I think all of your comments and the fact that the shots look so similar to all tell me the differences in optical quality are minimal, if any, and the advantages simply go to build quality, 1.8 vs. 2.8, and perhaps better bokeh. I know these pcitures may not be the best for judging differences in optical quality, but I think that further shows the differences go more to build quality, wider aperture, (size), and bokeh.

Thank you all for your help.

I appreciate the significant input.

Gregg
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