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Old Jun 26, 2009, 2:26 PM   #1
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Default DA 16-50mm f2.8

ok so i have been hovering on the buy button all day!!!!

i want a lens in this range and this one is in my price range. now what is stopping me is that i know this lens has had problems in the past. i think it's fixed now but just in case i get a lemon. i wanted to know is how i would tell if it does have issues.

if you have other suggestion for me i am willing to hear them too. i already have it's partner the 50 -135mm. i love it it's my favorite lens.
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Old Jun 26, 2009, 3:17 PM   #2
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I don't have the lens, but the way I go about checking out a lens is to use it in every day situations. Look at the edges of the frame, are the sides significantly blurrier than the center or is one side blurry while the other sharp? Did the lens focus where you pointed it (i.e., back or front focus issues)? Take pictures of subjects at different distances and with different apertures. If a picture is only really sharp at f16, you have a problem. If it's sharp in the center but really blurry at the edges, you have a problem. If you aren't sure, then take pictures of brick walls and ask for help with deciding whether yours is different than others.
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Old Jun 26, 2009, 4:43 PM   #3
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I do not have the lens either, however from what I remember the problems appeared to be early in the production. I do have the 16-45/f4 lens which I like very much. I do not feel the overwhelming need to go to f2.8, since I like landscapes. And for my night low light items, I am going to have the shutter open about 5 to 15 seconds, I do not see the need to go to f2.8 since I usually use something around f8 for depth of field.
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Old Jun 26, 2009, 5:52 PM   #4
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julianne
I just got the DA* 16-50 f2.8 last week. I really like it. I have a few photos posted here http://www.flickr.com/photos/steelmanpa/

Stevie
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Old Jun 26, 2009, 8:08 PM   #5
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Hi Julianne,

IIRC, the problem was decentered lens elements which is a QC problem, not a design flaw. This would cause increased blurriness on one side of the scene. The most common ways to test for this would be to shoot either a brick wall or a large newspaper at the widest aperture (in this case, at f2.8), making sure that the flat surface that you're shooting is very close to perfectly parallel to the sensor plane (measure it to make sure -- the points at the extreme edges of the frame are the same distance from the center of the camera.) Examine the shot carefully, both sides should have very close to equal sharpness, and both edges will be somewhat less sharp than the center. You should test this at various Focal Lengths since it's a zoom, and shoot from a tripod with SR off to get consistent results and eliminate camera shake and positioning as variables.

I think that the problems were largely overblown in the various Pentax fora, and you should be as unlikely to get a bad one as with any other lens from any other mfg. The reality is that just about any lens from anyone could be a bad copy, so the only way to ensure that any lenses that you buy are good are to make sure that the seller has a reasonable return policy, and that you test the lens right away to take full advantage of the return privileges if necessary. Even if the dealer's exchange policy proves to be less than ideal, you still have the Pentax warranty to fall back on if you buy new -- but you really shouldn't need it. . .

You do have a few alternatives though. Tamron makes an SP 17-50/2.8 and Sigma has their EX 18-50/2.8 and the 17-70/2.8-4.5. The Pentax DA 16-45/4 and DA 17-70/4 are some others -- the slower max aperture is offset by smaller lighter designs -- , but none of these is weather sealed (the DA17-70 does have an o-ring on the mounting flange, but isn't sealed anywhere else), so if WR is a wanted feature, the DA*16-50/2.8 is pretty much the only game in town.

Personally, I wouldn't hesitate to buy a DA*16-50 from a reputable dealer if I were in the market for this lens. I think that the manufacturing problems have been long since straightened out by Pentax, and the major dealers have easily had enough time to turn over the old stock of questionable QC examples.

Scott
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Old Jun 26, 2009, 8:26 PM   #6
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I have owned this lens for over a year and absolutely love it. It is my everyday walk about lens. The one complaint I may have is that it is a big lens (77 mm opening). But with the SDM focusing, it is silent and fast.
Here's a link to some pictures I took a couple of weekends ago. http://forums.steves-digicams.com/pe...-memorial.html

When I purchase a new lens, I use the following focus test chart to confirm some of the issues that Mtgal referred to (especially back/front focusing, unusual distortion, etc). I also recommend buying from a seller like Amazon.com which has a generous 30 day return policy (plenty of time to test out a lens).
http://focustestchart.com/focus21.pdf
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Old Jun 26, 2009, 8:59 PM   #7
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As a further note - I wouldn't hesitate buying one either, if I felt the need for one. Even if you decide that yours isn't right after the return period, there's the 1 year Pentax warranty. They were very responsive when I sent in my DA 55-300, replaced it right away.
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Old Jun 26, 2009, 10:11 PM   #8
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Quote:
Originally Posted by jelpee View Post
I have owned this lens for over a year and absolutely love it. It is my everyday walk about lens. The one complaint I may have is that it is a big lens (77 mm opening). But with the SDM focusing, it is silent and fast.
Here's a link to some pictures I took a couple of weekends ago. http://forums.steves-digicams.com/pe...-memorial.html

When I purchase a new lens, I use the following focus test chart to confirm some of the issues that Mtgal referred to (especially back/front focusing, unusual distortion, etc). I also recommend buying from a seller like Amazon.com which has a generous 30 day return policy (plenty of time to test out a lens).
http://focustestchart.com/focus21.pdf
hope you can help
i too have this lens and love it but,i never realised i had a back focus problem until i tried this focus test chart. i have not been able to make any head way with this chart as for some reason i get completely different results if i use different zoom settings and also different chart to lens distances. its never consistant.
is it that you only have a problem if the focus line is not clear?
do you adjust focus to a balance ?
do you adjust at an average of the different zoom settings?
do you adjust to an average to different distance settings?
do you adjust only for the 16mm setting?
my lens takes great pics but yet the focus chart says i have a very bad back focus problem that would require a +10 setting at 16mm, but only a +5 at 30
even my 50-135 lens takes stellar crisp photos, but yet the focus chart also inticates that that lens has a very bad back focus problem

What to do, what am i doing wrong. is this chart really for prime lenses and not zooms

Dave
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Old Jun 26, 2009, 10:21 PM   #9
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Quote:
Originally Posted by mtngal View Post
As a further note - I wouldn't hesitate buying one either, if I felt the need for one. Even if you decide that yours isn't right after the return period, there's the 1 year Pentax warranty. They were very responsive when I sent in my DA 55-300, replaced it right away.
i know you have a K20D and the 50-135
did you have to do any focus adjust for that lens?

Dave
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Old Jun 26, 2009, 11:43 PM   #10
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Wow!!! Thank you all so much I did not except such useful information.

Well itís a done deal. Contacted my local camera store and bought it. I donít have it yet because they have to order it but I should have it within the week. I finally have a wide angle.

I will certainly keep all this info for all my future lens purchases although I have everything I ever wanted now.
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