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11-09-2008, 12:53 PM   #1
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Testing my second DA*50-135mm

Hello all!

After seeing so many terrific photos from DA* 50-135mm, and ideal focal length for my "likes", I decided to get one. This actually a second copy for me, first one I got early this year, but was really terrible copy, did not focus, and noisy, low resolution images at any settings.

So to be honest with you, I was looking forward to come home and see some quality images after uploading, but that is not exactly how I feel. I never had a reason to test the lens ever before, but after looking through a dozen of images, I decided to question this copy.

Here are my findings (on the tripod, leveled tripod, leveled head, paper on the floor as flat as it could possibly be:

f2.8



f3.2



f3.5



f4



f4.5



f5



f5.6



f6.3




I expected some level of distortion, and did review the chart from photozone (this distortion is almost "inverted"??? I also expected some degree of "less resolution" in the corners, but... And does not improve all that much even at f6.3

Thoughts?

Regards,
D

11-09-2008, 01:00 PM   #2
Syb
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Are these uncropped? What ISO and what distance to the subject?

Those are the questions for me. I could understand some disappointment here. At least I would not be happy about this. Could it be a Front Focusing issue?
11-09-2008, 01:10 PM   #3
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All of these are original uncropped (just downsized in CS3) - raw to jpeg, ISO 100, 135mm about 4.5' from the subject. All EXIF data should be intact...

Focusing point - center, and that is the only area in focus here Even at f6.3... I'm really questioning why is distortion so odd too - misaligned elements?

Regards,
D
11-09-2008, 01:29 PM   #4
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Bummer, Duh Vinci. Have you tried this test with any other lens - preferably a macro? It is possible that the camera lens mount is not in proper alignment. This would be showcased by higher aperture lenses used wide open. High speed lenses usually have more curvature of field also. Looks like bottom of frame is sharper than top. Do you have another body to try it on to see if its the same pattern?
thanks
barondla

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11-09-2008, 02:02 PM   #5
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Tested DFA 100mm macro on the same K10D, wide open at f2.8:



Different, huh?

Regards,
D
11-09-2008, 02:08 PM   #6
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Do you have a filter on this lens?
11-09-2008, 02:12 PM   #7
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Nope, no filter. Fresh out of the box. Cleaned the contacts and surfaces on both, body and the lens too.

Not sure what is the best way to deal with it - got it from Prodigital2000, dunno how their customer service is for exchange works, or send it straight to Pentax?

Regards,
D
11-09-2008, 02:19 PM   #8
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QuoteOriginally posted by Duh_Vinci Quote
Nope, no filter. Fresh out of the box. Cleaned the contacts and surfaces on both, body and the lens too.

Not sure what is the best way to deal with it - got it from Prodigital2000, dunno how their customer service is for exchange works, or send it straight to Pentax?

Regards,
D
For one thing, I don't know how fair it is to test it against a macro prime - two very different lenses. Maybe try another zoom, same tests.

But, you know, I never once tried a test like this with my lens, and my everyday shooting results with the 50-135 are so good, I couldn't imagine being dissatisfied with anything a newspaper resolution test would show me at this point. Before you do anything why not give it a try outside, indoors, shoot some people/flowers/animals/architecture/cars, and see if you're pleased with it?

If there is a problem with the lens, it should show up in everyday shooting also.


.

11-09-2008, 03:05 PM   #9
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Thats just it, I've never been a pixel peeper, and never tested lens on paper before. But all shots (about a dozen shots from this lens) are less than desirable in terms of sharpness. I really don't even have anything to share...

Colors are terrific though:



Regards,
D
11-09-2008, 08:34 PM   #10
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Its not fair to compare it to a macro for sure. The reason that was done was to make sure the camera lens mount was aligned properly. It is. The test also shows what is possible. A perfect high speed zoom will never match a macro in this situation. Macros are designed for flat field. Thats why they are so expnsive. High speed lenses don't want to to flat field!
Doesn't look like the elements are lined up or something. A shame. Have a friend with both 16-50 & 50-135. Her prints will knock your eyes out in sharpness. She let me shoot them once (I got even because she got to shoot my 31 & 77) and they were beautiful. Only Pentax mount zooms that made me think of the Limiteds. Not quite the same look but getting there.
Good luck with your lens,
thanks
barondla
11-11-2008, 05:14 AM   #11
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QuoteOriginally posted by barondla Quote
... Have a friend with both 16-50 & 50-135. Her prints will knock your eyes out in sharpness....
barondla
That is what I was hoping for. Oh well, next copy

Question - on k10d, is it normal that this DA* 50-135mm does not show up under the EXIF - lens name section? If I remember correctly, every one of my Pentax lenses names come up...

Regards,
D
11-11-2008, 07:06 AM   #12
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I think the lens is fine. Don't come to a hasty conclusion that the lens is somehow not sharp simply based on the result of shooting a flat newspaper. I notice you're using a K10D. One of the reasons why I ditched my K10D is the focusing issues. Don't know if you were shooting RAW or jpeg, but from my observation the K10D's jpeg images straight from the camera need to be sharpened. Try the lens with the K20D and the results may well be better. Secondly, it is pointless to compare the lens with the DFA macro as macro lenses are flat field corrected, a must when used for copying.
11-11-2008, 07:57 AM   #13
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QuoteOriginally posted by creampuff Quote
I think the lens is fine. Don't come to a hasty conclusion that the lens is somehow not sharp simply based on the result of shooting a flat newspaper. I notice you're using a K10D. One of the reasons why I ditched my K10D is the focusing issues.
If it is a body issue, then the same should be true for all and any lens on it ...
11-11-2008, 08:35 AM   #14
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QuoteOriginally posted by gkopeliadis Quote
If it is a body issue, then the same should be true for all and any lens on it ...
Not necessarily. For example the DA 21 has had a bad rap with the K10D focusing wise, but on the K20D it is perfect. Coming back to the DA* 50-135mm, a few friends I know who have it with the K20D, myself included, either didn't have to adjust anything or made a slight adjustment to the focus point.
11-11-2008, 08:55 AM   #15
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Got my 50-135 a few weeks back, and its on the edge of blury will send it in and hopefully they will agree with me and fix it. Even with manual focus, tripod, and shakereduction off it wont get sharp
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