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mtngal Feb 21, 2011 4:58 PM

DA 12-24 issues
I'm having some problems and I think one of them is my DA 12-24. I know I'm not the only one out there that has this lens and it's known for being incredibly sharp. Mine is excellent at objects close up, very sharp. However, objects that are a long way off don't seem to be right. In addition, I've noticed the edges, both right and left look pretty bad, even at f8. I've uploaded a bunch of full sized, unaltered files (either shot in jpg or else uploaded from dng using Lightroom's default settings and Jeffrey Friedl's plug-in to upload to zenfolio. I sometimes think I'm asking too much from this lens, but when I went looking for examples to post I got more confused instead of less. I'd really like for others who own the lens to look at my examples and let me know what they think.

The album is at: , you can tell which camera took which picture by the file name. Most were hand-held, though the last one was taken with the camera on a tripod and SR off. There was a variety of light levels used. If you hold the curser over the left edge of the picture a fly-out panel with a couple of icons on it appears, one that will allow you to download the original files. Or if you don't want to download them, some of the full sized files are at: (this and the next one were taken at different times but from similar locations with two different cameras) This and the following 5 pictures were all taken the same day in Death Valley and the ones I'm most disappointed in - for people who want to pixel-peep K5 pictures taken at ISO 16,000, this file might be interesting. I didn't use any noise reduction, except I think LR might apply some in the default settings, didn't think about turning that off. This was taken the next day The rest were taken more recently.
The next two were taken with the camera mounted on a tripod and SR turned off. The first one the focus point was the rebar - with a subject so far away, I would think the trees behind it would also be sharp. The second one the focus was the bare tree beyond the rebar.

Before I say what I've been thinking, I'd really like someone who's objective to look at them and tell me if I have a problem lens or if I'm just expecting too much from such a wide angle lens. I've been shooting and looking at different shots, taken under different conditions and different cameras and have completely lost objective perspective about it all.

And a final question - can a lens develop optical alignment problems over time either due to damage or some other factor?

nhmom Feb 21, 2011 5:07 PM

I had bought a Pentax 18-250 from someone on Craig's List a while back. It was great up close, but distances it was very blurry. I got my money back from the guy. He did send it into Pentax for repair and said it came back perfect.

He had told me he'd never had any problems with it. Wasn't sure what had happened. He hadn't used it for a while before he sold it to me. And, I was at the zoo using it within an hour of buying it from him.

So, I would say yes they can develop alignment problems over time.


lesmore49 Feb 21, 2011 7:15 PM

"I'm having some problems and I think one of them is my DA 12-24. I know I'm not the only one out there that has this lens and it's known for being incredibly sharp. Mine is excellent at objects close up, very sharp. However, objects that are a long way off don't seem to be right. In addition, I've noticed the edges, both right and left look pretty bad, even at f8."

I looked at your 24 pictures on your sample set and some of the other pictures you had.

I didn't look at all the pictures...just a sampling.

I enlarged those that I could, looked at a few corners, looked at the objects that were near and those that were far away.

I have a Pentax 12-24mm and I use it mostly on my K10D, also on my KM.

Your pictures looked fine to me, whether I examined the edges, close or faraway objects...with blowing them up, when I could.

Now I'm no spring chicken :D and I use I may not be the best person to make a judgment.

But they looked good to me and not to much different from my 12-24 / K10D combo.

I wonder if you should try taking the same pix, same lighting, same approx. angle of view with one of your other Pentax lenses vs your 12-24 ? I'm sure you've done this, but I can't think of any other test off hand.



The last picture...with the #'s 907 in the link....looked a little funny. I felt that the courtyard seemed clearer...both the building and the ivy growing on the wall, compared to the trees in the background...which seemed blurry.

Then it hit me...the courtyard and ivy in the foreground is protected by walls from the wind...the Evergreen tree branches, in the background seem to be, IMO...being blown by the wind...hence the blurriness in the background, but not in the foreground.

Could this be what your seeing ?

mtngal Feb 21, 2011 9:25 PM

Thanks, Les. I think that the first few pictures are fine, the 2nd and 3rd that were taken from a similar location but at different times and different cameras looked very similar as far as distant objects. The Oceanside picture is also fine in my opinion. However, the Death Valley pictures show problems - the first one (taken in low light) show a reasonable foreground but oof distant mountains, while the mountain silhouette (taken within the same minute but in entirely different directions so different light levels) appears sharp. Then the pictures of the dirt road also seem to me to have blurry distant mountains but a sharp foreground - in the one at Leadfield, the Jeep is sharp. The low-light pictures in Scotty's Castle look sharp, even the one that's front focused a bit is sharp where it did focus. But there the subject was quite close. I can't decide about the one with the reflections. While I think it looks better than the couple from the day before, I don't think it looks as sharp as the first few. I don't think it was windy the day I took the last two (I don't remember that it was), but I should probably take some pictures of the high-rises instead, to see if it makes a difference.

If others think the same as I do - that there's a definite difference in the lens from the first couple of shots to the ones in Death Valley, then something happened to the lens from one day to the next (the Oceanside picture was taken two days before the Death Valley pictures). Originally I had thought that the camera had a problem with this lens, then when some comparison shots I took of the construction site with the K7 looked just as bad, I thought perhaps the lens had always been faulty (I don't use it all that much). But as I was pulling examples to post in a thread asking for advice, I took a good look at the two mountain scenes and thought they looked pretty good. So then I started thinking my expectations were just too high for the Death Valley pictures so I thought I would ask for someone else to look at them.

Biro Feb 22, 2011 6:10 AM

Harriet... I took a look at the images you are most-disappointed in and, yes, I can see mountains in the distance definitely look quite soft. I just took a look at some images of my own taken with the 12-24 to confirm that kind of performance does not appear to be normal. I would upload them here but it wouldn't be useful - none of my shots look all that sharp after using iPhoto to upload to outside websites. I would suspect alignment problems - probably quite slight in this case. Do you think you bumped the lens somehow on the trip?

mtngal Feb 22, 2011 10:39 PM

It could have gotten bumped either on the trip or before. We drove the Wrangler and it was in a camera bag in the back - could have gotten knocked around some. I've set it aside for the moment and I'm playing around with some of my other lenses, to make sure that the rest are all working well. I'll most likely send it in for repair, it's such a useful lens and its too expensive to write-off. Though I am a bit scared of how much the repair bill will be (assuming they can fix it).

The one lens that I did drop on the vacation was the DA*200. It rolled off a table onto a chair and then to a cement patio - ouch! I think it broke one of the "fins" on the hood mount, but the lens is fine, used it today as a matter of fact.

mtngal Feb 28, 2011 10:04 PM

I took some more pictures with the 12-24 today. This time I used a tripod for both cameras and took pictures of tall buildings a block or two away. There wasn't a huge difference between the two cameras for the most part. In one case the lens didn't quite focus right with the K5 (picture obviously blurrier), while the other pictures were all equal or better with the K5. The lens has a bit more distortion on the left side than the right, but both sides have a fair amount more than the center. I think there's something wrong with the lens, but I'm not as interested in sending it in as I was, since it's out of warranty. It isn't all that bad, and the one shot that was not focused right, wasn't significantly off, just slightly fuzzy (or maybe I moved the camera slightly. Even though it was mounted on a tripod I wasn't using a remote).

I still don't know why the outdoor Death Valley pictures were so bad.

Biro Feb 28, 2011 10:24 PM

More distortion one on side than the other? That sounds like decentering to me. Will Pentax give you a quote before sending it in? The 12-24 is a great lens - definitely worth repairing (unless you're about to pull the trigger on something truly great).

snostorm Mar 2, 2011 6:00 PM

Hi Harriet,

I hate lens tests, but. . .

Maybe the best thing you could do is test it with a newspaper page taped flat to a wall. Lightly iron the page to take out the creases. Use a tripod and remote shutter release or (probably better yet) flash to eliminate camera shake issues, and measure the distance to each side of the paper to make sure that you're absolutely square. It sounds like more work to set up than it is, but for a lens of this caliber, I think it would be worth it. The point is to eliminate as many variables as possible. Shoot starting wide open, then stop down gradually, all with the same setup.

If the lens is decentered, you'll easily be able to see more distortion or blur in the text on one side of the frame than the other. If nothing else, you may be able to determine at what point stopping down might overcome the problem, so you still might be able to use the lens with confidence with higher ISO and smaller apertures.

If the lens passes, then you have to figure out what you might be doing wrong technique-wise, but at least you'd know the lens is good.


mtngal Mar 2, 2011 9:00 PM

That does sound like the next step, since I'm convinced the lens can really focus to infinity. I'm beginning to wonder about the K5 and focus points - I always leave the camera on center focus point but I was wondering if the switch wasn't quite right or something else was going on and the camera was choosing the bottom focus point, causing the camera to focus on the foreground instead of the distant mountain. Or something like that. I changed the camera to select focus point for a while, then back to center focus and I haven't been able to get the camera to mis-focus again.

Maybe next week I'll get out the classifieds and see about possible decentering.

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