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04-06-2010, 11:27 PM   #16
TKH
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QuoteOriginally posted by twitch Quote
I'm no expert, but those shots (assuming they are not cropped) look like they were taken with a seriously decentered lens. The right edges are sharp, whilst the left are very blurry. If that isn't a decentered lens then I don't know what is. I wouldn't hesitate to return that lens and get another DA15.
QuoteOriginally posted by Marc Sabatella Quote
I don't see that at all. The crops are only from the left side, so how can you tell anything about the right side?
QuoteOriginally posted by tokyoso Quote
how about a crop from the boats on the right side from the second pic?
I think the same way twitch thinks.

Lets see again:

f8; 1/1000


crop left


crop right




Rainer

04-06-2010, 11:33 PM   #17
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Same here:


f6.7; 1/350


Crop




twitch hit the point.

To show it correctly I will take pics with a tripod from a big stone wall where the dof is equal.
But I dont think that the result will be in any other way. IMHO its a shame that Pentax Germany (März Servicecenter Hamburg) checked the lens two times (after buying) and quoted it as OK and adjusted.

Rainer

Last edited by TKH; 04-06-2010 at 11:49 PM.
04-06-2010, 11:38 PM   #18
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The $42 dollar question is are we, or are we not, looking at a cropped picture. If it is not cropped then that lens is unacceptably decentered and should go back. If we are looking at cropped then seeing the whole image would help....
04-06-2010, 11:42 PM   #19
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thanks, are you comparing the bricks on the buildings or the boats? i can't really tell the difference and i really don't know the difference if i see it, tbh. i guess i'm luckky the good and bad all look good to me. hehe

actually, i'm considering to get this lens as well. is it appropriate to ask if the DA 15 is more "optimized" for close up centered subjects such as portrait shots than say something like landscapes?

04-06-2010, 11:45 PM   #20
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QuoteOriginally posted by twitch Quote
The $42 dollar question is are we, or are we not, looking at a cropped picture. If it is not cropped then that lens is unacceptably decentered and should go back. If we are looking at cropped then seeing the whole image would help....
The first pics in the last two postings are always nearly the whole image. (I only adjusted the right angel).
Here you can see for example the second one with all settings back:


Last edited by TKH; 04-06-2010 at 11:53 PM.
04-07-2010, 12:49 AM   #21
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I hadn't seen your post with crops before I posted my $42 response, I was a bit hasty with my assertion it is was unclear whether we were looking at crops.

Now, given those crops you've posted I'm even more sure that your lens is decentered to the right & bottom. It's not acceptable IMHO.
04-07-2010, 03:36 AM   #22
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I agree also. It is decentered badly. Maybe you should you demand a new one if they can't seem to repair it properly.

.muus
04-07-2010, 03:43 AM   #23
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well from what I have seen, it's a crap lens

The kit at 18 is better as is the 16 end of the 16-45.

For the price of that one lens I reckon it's better to have the zoom 16-50 2.8

04-07-2010, 07:22 PM   #24
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QuoteOriginally posted by dylansalt Quote
The kit at 18 is better as is the 16 end of the 16-45.
Based on the photozone test results, the zooms have more pronounced barrel distortions. The 15mm is very well corrected - even better than the 21mm. The only one coming close to it is the 14mm. Lack of distortions is a big deal for a wide-angle.
04-07-2010, 09:03 PM   #25
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QuoteOriginally posted by dylansalt Quote
well from what I have seen, it's a crap lens

The kit at 18 is better as is the 16 end of the 16-45.
I assume you are referring to this sample only? Because quite clearly looking at the general range of images as well as objective tests, neither statement is close to true. the 15 *blows away* the 18 end of the 18-55 in every possible way, and it also beats the 16 end of the 16-45 quite handily in almost all respects - the 16-45 wins only in corner sharpness wide open, and considering it isn't as wide as the 15, that might not be a real win in practice. In all others respects - center sharpness, corners stopped down, distortion, CA, flare resistance, etc - the 15 wins.

I would agree that now that we see the right crops, it does look like decentering on this copy, although I also agree that it would be prudent to do a more controlled test to verify this.

QuoteQuote:
For the price of that one lens I reckon it's better to have the zoom 16-50 2.8
Well, a 16-50/28 is far more versatile, of course. But you pay for that - it's a big big heavy zoom that don't go as wide, it costs significantly more, and it isn't quite as good optically (very similar in overall sharpness results, but with significantly more distortion and CA). There's really not much comparison between the two overall; they serve different needs.
04-08-2010, 01:18 PM   #26
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i think it's safe to say the DA 15 is a real nice lens. lemons and sample variations happens with all brands. it's probably just a matter of warranty issues.
04-08-2010, 03:07 PM   #27
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Threads like this make me want to test all my lenses. Paranoid, moi?

QuoteOriginally posted by Marc Sabatella Quote
the 15 *blows away* the 18 end of the 18-55 in every possible way, and it also beats the 16 end of the 16-45 quite handily in almost all respects - the 16-45 wins only in corner sharpness wide open, and considering it isn't as wide as the 15, that might not be a real win in practice. In all others respects - center sharpness, corners stopped down, distortion, CA, flare resistance, etc - the 15 wins.
That's not what I have seen in images I've looked at. Wide open and in the corners the DA16-45 seems to have the edge, as does the DA12-24. The DA15 only gets very good stopped down a fair amount.

However, I do not own the DA15 and so this is only second-hand.
04-08-2010, 05:22 PM   #28
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QuoteOriginally posted by rparmar Quote
That's not what I have seen in images I've looked at. Wide open and in the corners the DA16-45 seems to have the edge, as does the DA12-24.
That's exactly what I said: the one and only respect in which the 16-45 wins is in the corners wide open, and the same is true of the 12-24. Centers, the DA15 wins at all apertures (if not by enough to matter), and stopped down (which is the the only way you normally get corners in focus) the DA15 corners match or exceed the others, too. And when you compare distortion, CA, or flare resistance, it isn't even close - the 15 just *smears* the others.
04-08-2010, 05:29 PM   #29
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QuoteOriginally posted by Marc Sabatella Quote
That's exactly what I said: the one and only respect in which the 16-45 wins is in the corners wide open, and the same is true of the 12-24.
Sorry, I did understand you, but made perhaps a confusing use of that annoying English "and". I meant that the DA16-45 looks better everywhere wide open and in the corners all the time.

Now we at least know in which respects our opinions differ.
04-08-2010, 08:20 PM   #30
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QuoteOriginally posted by rparmar Quote
Sorry, I did understand you, but made perhaps a confusing use of that annoying English "and". I meant that the DA16-45 looks better everywhere wide open and in the corners all the time.

Now we at least know in which respects our opinions differ.
I originally had something in my post wondering if that's what you meant, but ended up editing it out. Anyhow, you're right that we disagree on this. Feel free to point to samples that you think support the notion that the 16-45 beats the 15 in the center wide open or in the corners at f/8 or f/11. I'll just observe that photozone agrees with me :-). Center MTF results wide open are 2308 to 2261, and corner MTF results at f/8 are 2086 to 1896 ("border") and 1951 to 1809 ("extreme") - all in favor of the 15. I'm not claiming any of these differences are significant enough to actually matter, but I am suggesting that the notion that the 16-45 beats the 15 in these respects doesn't hold up well to testing. I'm guessing your opinion was formed by sample images - not controlled tests - that just happened to show differences in DOF / focus plane.

I don't have the 16-45 to compare with, and I've never seen direct controlled tests performed by anyone else, so the photozone numbers are all I can really go on here. But I would say that when corners are in focus at f/8 on my DA15 - not by any means a common occurrence, because while DOF might be pretty big, so is the FOV - the results are pretty much exactly as sharp as these numbers would suggest.
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