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View Poll Results: Is this DA*16-50mm good or bad?
Keep it -- it's good. 2388.46%
Return it or send it in for repair. 311.54%
Voters: 26. You may not vote on this poll

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04-04-2008, 05:56 PM   #631
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QuoteOriginally posted by thear Quote
Your focus chart is not flat; which, may affect your test results. I thought my 16-50mm lens was bad; but, it turned out to be user error when I was performing the test.
I've done this test dozens of times, with an even flat focus chart, on tripod, SR off, and got the same result...

04-04-2008, 06:06 PM   #632
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The chart does not appear to be parallel/leveled correctly. Retest the lens at different focal lengths and aperture on newspaper or a book. Make sure the lines on your focusing screen is parallel to the lens on your focus chart.

Last edited by thear; 04-04-2008 at 06:12 PM.
04-04-2008, 08:34 PM   #633
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QuoteOriginally posted by reddream Quote
I've done this test dozens of times, with an even flat focus chart, on tripod, SR off, and got the same result...
And are you absolutely sure that the plane of the focus chart and the plane of your sensor (focal plane) are parallel? At such close focus distances and wide apertures any sloppiness in your test setup will end in misleading results. I'm not saying that your lens is perfect and you're imagining things, I just think that we all need to step back and take a breath, and remember that there are a lot of variables that need to be taken into account when attempting to do any kind of empirical test.
04-04-2008, 08:57 PM   #634
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QuoteOriginally posted by reddream Quote
I've done this test dozens of times, with an even flat focus chart, on tripod, SR off, and got the same result...
then why did you post an image with what looks like a crumpled up focus chart? What do the other ones look like? Distance from the target? Does it change when stopping down?

04-05-2008, 01:14 AM   #635
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Sorry if this is off topic, but I have a question.
At school we are doing a triangles unit (which is verrry boring) and I was wondering something:
In my picture, wouldnt the edges be out of focus because they are not in line?
If you stopped down, of course it would minimize those effects, so they would be covered up?
So based on that, by focusing in the center shouldnt the edges actually be out of focus, when the lens is wide open?

BTW this is a very rough sketch, but I would expect if I measured it out it would be accurate.
Please forgive me if I make no sense .
Thanks
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04-05-2008, 01:19 AM   #636
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QuoteOriginally posted by ranamar Quote
Sorry if this is off topic, but I have a question.
At school we are doing a triangles unit (which is verrry boring) and I was wondering something:
In my picture, wouldnt the edges be out of focus because they are not in line?
If you stopped down, of course it would minimize those effects, so they would be covered up?
So based on that, by focusing in the center shouldnt the edges actually be out of focus, when the lens is wide open?

BTW this is a very rough sketch, but I would expect if I measured it out it would be accurate.
Please forgive me if I make no sense .
Thanks
I wonder the same too; but my guess is that's what Klaus is referring to as field curvature in his review. Good lenses are supposed to have a flat focusing plane(as in your horizontal line)? Also, I believe the circle should be centered at the person/dot.
04-05-2008, 02:04 AM   #637
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You are right to a point. Lenses are very different than a straight geometrical graph though. They have corrective elements (aspherical glass and other correction characteristics) So they are designed to give the best corner to corner image possible for a given design. Better glass does a better job of this but even cheap lenses are pretty good at rendering a "flat field". The masters of this are the macros. Any decent macro lens will give the best flat field image of any lens in a similar focal range. It's why most will say that a FA SMC50mm f1.4 is a great lens but the FA SMC 50mm f2.8 macro is one of the best lenses, period. It's just sharper across the entire image and needs to be in order to work as a macro at such close focus distances and limited DOF's.

The issue here (and I can't offer an opinion to the OP with such a poor image/setup to evaluate) is that one side appears sharp and the other is soft. Assuming that the paper is flat and parallel to the camera, then this should not happen. Particulalry with a lens of this calibre and cost.

I would set the camera on a tripod and tape a flat test chart to the wall. Then measure each side of the camera body from the back to try and get the camera as parallel as possible to the test chart. That would tell me if there is an issue.

Personally I've given up on this lens (2 tries and no luck-sadly as I really wanted and needed one). Pentax has an issue here and they need to do something about it. It's like selling pace-makers with faulty batteries that work 50% of the time. Eventually the doctors will realize the product is no good and switch to another supplier.
04-05-2008, 04:51 AM   #638
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QuoteOriginally posted by Andrew Faires Quote
I've been pleased with mine. It's got better colour than my 14mm and at 16mm & 24mm, it resolved better than both my 14mm and 24mm primes, edge to edge. The only lens I have in that range that beat it was my 43mm.

The only draw-backs to this lens (my copy of it) is that it has a bit of zoom creep going from 16mm to 18mm, I can't use my singh-ray polarizers on it without vignetting at the wide end (Cokin size 'P') and while it's a very solid lens, it's not as solid as my old FA*24mm.

The advantages of this lens are that the SDM is very quiet, which I appreciate and it's weather-sealed (which I've tested quite thoroughly and been pleased with). Just for the weather-sealing, I consider this lens worth it.

My piece of advice is you go to the store and try the one you're thinking of buying out. There have been a lot of duds out there and it'll save you a lot of grief if you can confirm you've got a good one before you pay.

many many thanks,

of what I have to pay attention?

Davide

04-05-2008, 06:55 AM   #639
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If you do walk around in bad weather, sit on sandy beaches or travel over dusty savanna's, what other good alternative do you have, except for taking exceptional care for your lens?
There is none, except for the 16-50mm!

Also, why have this weather sealed camera if you do not buy weather sealed lenses with it?

I got lucky, I'm satisfied and very happy with my copy.

- Bert
04-05-2008, 11:19 AM   #640
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QuoteOriginally posted by Davidex Quote
Hi to everybody,

i would like to know your opinion.

is it worth the money?

Some people says no other yes.

What do you thin about?

Davide
Italy
I am very happy with my DA* 16-50. That f/2.8 combined with the 16mm makes it a great walk around lens. Here is a shot from a concert last night. I took this sitting in the aisle using available light (?). Image was processed in DxO using defaults. AWP, Program mode with USER settings.
1/30 @ f/2.8, ISO 800.
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04-05-2008, 11:28 AM   #641
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Simple answer: yes!

Even if there are more bad copies than would perhaps be allowable, consider this lens good. I answer yes even if I have had my share of troubles with this lens.

For the money you very practical normal range, good IQ, fast and silent focusing, fast aperture and weather proof build combined with excellent Pentax smc coating.
04-05-2008, 01:48 PM   #642
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QuoteOriginally posted by Peter Zack Quote
Personally I've given up on this lens (2 tries and no luck-sadly as I really wanted and needed one). Pentax has an issue here and they need to do something about it. It's like selling pace-makers with faulty batteries that work 50% of the time. Eventually the doctors will realize the product is no good and switch to another supplier.
I went to 3-4 different stores to try 4 different models before I found one that was really good shape. I didn't do any sort of graph test though. I could tell that the back-focusing and front-focusing was going to be an issue the moment I just took it in a test run in the store. Put the lens on camera, focus on object at a 50mm and 16mm (at F2.8) and see if it's sharp or fuzzy.

I haven't done any ruler test yet, and I'm afraid I may find some 'error' on my lens if I do so. But if this lens has little blurs here and there, I take it as part of the character of the lens (I know it's not going to be uber prime sharp across the entire picture... but it's pretty darn close). Otherwise, I'm still quite happy with this lens and just have to learn it's character.
04-05-2008, 05:49 PM   #643
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dugrant153. But that's exactly my point. You had to test 4 lenses to get one good one. Even Ben K returned his copy. This isn't a $89.00 kit lens (which remarkably, has better QC and IQ than 75% of the DA*16-50's). It's a $700+ premium lens from a company that was and still is renowned for some of the best glass in the business. Just unacceptable in my book.

I want a good sharp and fast wide zoom for personal and paid work. I wanted this lens partly because it's a bit wider than the Sigma and Tamron and because of the SDM and weather seals. No other supplier offers all this in one package. I have to have it by the end of May so I guess in my case it will be a Sigma Macro 18-50 f2.8 or the Tamron 17-50 f2.8.
04-05-2008, 11:25 PM   #644
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Don't know what all that fuss is about, that lens is a keeper. The crumpled paper bit is a bit sus to me.
04-06-2008, 12:24 AM   #645
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QuoteOriginally posted by Peter Zack Quote
dugrant153. But that's exactly my point. You had to test 4 lenses to get one good one. Even Ben K returned his copy. This isn't a $89.00 kit lens (which remarkably, has better QC and IQ than 75% of the DA*16-50's). It's a $700+ premium lens from a company that was and still is renowned for some of the best glass in the business. Just unacceptable in my book.

I want a good sharp and fast wide zoom for personal and paid work. I wanted this lens partly because it's a bit wider than the Sigma and Tamron and because of the SDM and weather seals. No other supplier offers all this in one package. I have to have it by the end of May so I guess in my case it will be a Sigma Macro 18-50 f2.8 or the Tamron 17-50 f2.8.
You're right in that it's quite unacceptable. Heck, even I gave up on the lens when it came out a few months ago. I do think it's quite an issue when the failure rate is pretty high. I think I would've been like you too in that I would've purchased a Sigma or Tamron F2.8 similar zooms, but I got lucky and found this copy. Good luck to you on finding a good lens, reddream. I heard the Sigma was a decent competitor For me, it was either a Sigma 18-50 F2.8, or two DA limited prime lenses.

Anyways, I guess what I was trying to say was that I prefer to test lenses in the real world, versus taking the numbers of a focus chart. The 4/5 DA* lenses I tried that failed were tested right in the store/convention, and they failed miserably from the get-go. That was more than enough for me to put my money back in my pocket.

I'd like to see how reddream's lens does in real world pictures.
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