DA 55-300 - Problem or normal?

mtngal · 06-03-2009, 09:32 PM

I've had the DA 55-300 for a while now and haven't been completely happy with it. I'm not sure if my copy might be faulty or if I just have become too picky when it comes to lens quality (my usual lenses are the DA*50-135, A*300, Viv Series 1 105mm macro, DA 12-24, and 77 Ltd). I'm trying to decide if its worth it to send the lens in for warranty service or not, or if I should get rid of it and buy a bigger, heavier, higher quality, more expensive lens like the Tamron or Sigma 70-200 f2.8, or DA*200 f2.8 or DA*60-250 (I have a 50-200 which I suspect had problems from the beginning, and which is definitely broken now). I really want something around 200mm - I find I really wish I had something between the DA*50-135 and the A*300.

My problem is the edges. It isn't so much that they are soft, as they are distorted. It doesn't happen all the time, and it's not always at 300mm.

An example (190mm 1/320 sec f7.1):

These pictures were taken in raw and I used a LR plug-in to convert to jpg and upload to zenfolio, using whatever LR's default settings for conversion. The full sized file is at: http://mtngal.zenfolio.com/img/v1/p594385645.jpg if that would help at all.

Another shot, taken at the same spot at 55mm. You can still see some distortion at the edges, though not as much. You can also see that the power lines are not appreciably closer than the trees, they are well into the infinity focusing range.

Full sized file is: http://mtngal.zenfolio.com/img/v3/p680800334.jpg

The edge distortion isn't always there, though. Here's another picture that doesn't show much at all (107mm 1/320 sec. f7.1)

I don't notice much distortion on this one, though you can still see it on the full sized picture ( http://mtngal.zenfolio.com/img/v4/p555544665.jpg ).

I'm not sure these are the best pictures, but they are what I have handy at the moment. I shot some brick wall pictures a while back and thought they looked fairly reasonable, but then I'll get stuff like this. I've been trying to get out of the office this week to take more at lunchtime but haven't managed it.

My questions are, are these normal photos from this lens? If so, I'll probably get rid of the lens and buy a better quality lens, which wouldn't be my first choice since weight is a big issue for me. Does it look like the lens has something wrong with it and should I send it back to Pentax for repair?

Thanks very much for the feedback.

*imtheguy* · 06-04-2009, 01:34 AM

I would like to help but dont have your eye for the problem. i have taken thousands of shots with my 55-300mm this spring but rarely pixel peep the edges as my subjects are always critters. Although I see some softness on the full size pics you linked I have no idea what specific distortion you refer to. If you can provide me samples I can duplicate with my lens such as the brick wall pic and settings maybe my pics can help you decide what to do. I am happy to help if I can.

Dom · 06-04-2009, 01:42 AM

Try taking some photos of a brick wall, it should show up any distortion and make it easier for use to see it.

*deadwolfbones* · 06-04-2009, 08:00 AM

Originally Posted by imtheguy

I would like to help but dont have your eye for the problem. i have taken thousands of shots with my 55-300mm this spring but rarely pixel peep the edges as my subjects are always critters. Although I see some softness on the full size pics you linked I have no idea what specific distortion you refer to. If you can provide me samples I can duplicate with my lens such as the brick wall pic and settings maybe my pics can help you decide what to do. I am happy to help if I can.

Yeah, I agree. I don't really see what's wrong with these.

mtngal · 06-04-2009, 02:27 PM

Thanks for the replies, I'm beginning to think that it's just me and that what I look for in a lens has gotten too high. I spent lunch taking a bunch of brick walls, this time in jpg, with and without tripod, with and without SR, at different distances, focal lengths and apertures. I'll post some this evening. Depending on what I see on the monitor tonight, I might try shooting with the K100, in case its more related to my particular K20 (I'm rather reaching for straws here, I know).

Thanks for the feedback so far.

dylansalt · 06-04-2009, 02:58 PM

The 55-300 is a very very good consumer zoom for sure but why on earth are you trying to justify it's performance against lenses which are are classified as "pro" grade lenses and 4 times the price?

Dyl

Alfisti · 06-04-2009, 03:04 PM

Originally Posted by dylansalt

The 55-300 is a very very good consumer zoom for sure but why on earth are you trying to justify it's performance against lenses which are are classified as "pro" grade lenses and 4 times the price?

Dyl

Because at f/9 and away from the extremes of focal length and frame edges there should be very little difference.

**Marc Sabatella** · 06-04-2009, 03:19 PM

I'm just wondering how we're supposed to be able to judge distortion in a picture of the sky. Do you have an allegedly undistored picture of those same clouds to compare against?

mtngal · 06-04-2009, 10:13 PM

Actually, it wasn't the sky I was looking at - it was the silhouette tree line. But I did take a bunch of pictures of several brick walls, some in shadow, some in relatively bright sunlight, some with SR on, some with SR off and the camera mounted on a tripod. I varied the aperture and the distance (I've sometimes thought the blurriness at the edges seemed to be more noticeable at longer distances). I came to some conclusions - SR didn't make a difference as I saw some blurriness with the tripod mounted pictures. Aperture makes some difference, but not as much as I would have expected.

Here are the brick walls:

SR on, hand held, f6.3, 1/320 sec. 285mm, jpg straight from camera:

Full sized file at: http://mtngal.zenfolio.com/img/v6/p330053405.jpg .

Tripod mounted, SR off, f8, 1/320 sec. 210mm:

Original file: http://mtngal.zenfolio.com/img/v2/p292521651.jpg

Same as above except f11, 1/200 sec.

Original: http://mtngal.zenfolio.com/img/v3/p121241346.jpg

Same as above except f16, 1/200 sec.

Original http://mtngal.zenfolio.com/img/v5/p49921886.jpg

It seems like there's still a fair amount of edge softness at f11, and it only clears up at f16.

Here's the same wall, taken quite a bit further away (it's not at infinity, but it was as close as I could get). The bit of grey bollards on the sides don't count - they are significantly closer than the wall is. But you can still see quite a bit of softness on the bricks.

f8, 1/320 sec. 230mm.

Original http://mtngal.zenfolio.com/img/v8/p349552340.jpg

Compare the one above to this one, which is f22, 1/200. At least the edges don't look blurry here, compared to the center.

Original http://mtngal.zenfolio.com/img/v6/p65393143.jpg

I know that this is supposed to be about as good as it gets for this class of lens. So I really want to know if there's something wrong with my particular lens - in which case, I'll send it in for repair. If this is as good as this class of lens gets, then I'll probably sell this one and move up to a better class of lens. I really don't know if the problem is the lens or what I'm willing to accept, it could be either.

*imtheguy* · 06-04-2009, 10:32 PM

Yikes....I didnt expect to see anything but bricks and i went straight to the f/8 as that should be the top IQ of the bunch corner to corner but wowsa! That looks like a lot more pin cushioning than I figured on at 210mm. I didnt expect any at that length. Whether i can help or not i need to find a brick wall tomorrow and repeat with my lens. I may be in for a rude shock and some new reason to re-up my DxO.

How about notating a couple areas where YOU see the distortion rather having everybody look for it? Not talking edge softness, just the distortion (what kind?) you stated to open the thread.

1 more edit - How far away were you from the wall?

mtngal · 06-05-2009, 08:45 AM

Thanks for the reply - I want to say that the series from the same place was about 20-30 feet from the wall, the last 2 were across an alleyway as well as the plaza - I want to say close to 100 ft or more (I'm terrible at distances). I had even made sure the camera was level.

In the first picture I posted, what I was looking at was the silhouette treeline. I called it distortion but I probably should have used the term "significant blurriness" - it's well beyond what I would call "soft". The sunset picture at 55mm is what I would call soft at the edges. The brick wall doesn't look as bad, though the left and right edges are far softer than I want at f8 and f11.

It's interesting that you pointed out the rather pronounced pincushioning - I wonder if that's another part of whatever is wrong with this particular lens. I don't notice it when I'm shooting since I use this lens for a hiking/walk-about lens and I haven't been shooting much architecture recently. I do notice the very blurred edges, something that really affects landscape pictures.

P.S. I would love to see some of your shots of a brick wall (sorry to include the cement block but the buildings around here pretty much break up the brick pattern in some way).

dylansalt · 06-05-2009, 10:15 AM

Originally Posted by Alfisti

Because at f/9 and away from the extremes of focal length and frame edges there should be very little difference.

To be quite honest - I never realized this

To now know that my kit lens and the 55-300 perform very very close in the middle apertures (IQ wise) to the Ltd's and other "pro" grade lenses - am stoked

Thanks for the heads up

Dyl

mtngal · 06-05-2009, 01:05 PM

If you only look at center sharpness, I think that even my DA 55-300 at f8 isn't all that much different than my DA*50-135 at the same focal lengths. Yes, I did take some comarison shots when I first got the 55-300.

I'm really hoping that someone will tell/show me that my lens is faulty, because the higher quality equivalent lenses have some disadvantages.

*imtheguy* · 06-05-2009, 07:17 PM

I have my 55-300mm pic of brick wall ready to go but cant squeeze it into the allotted web space on my ISP. Time to find someplace I can move >10MB pics which I have not been doing up until now.

bottom line is a shocker to me ---> MTNGAL, your brick wall at f8, 100' took a pin cushion adjustment in PE7 of -3.0. When i took almost the exact same pic except mine was under clouds thus higher ISO but same shutter of 1/320, my brick wall of f8, 100' needed an adjustment of -2.80 which is the exact same thing. I just did it manually without thinking of what your adjust was. Side by side, ours look the same as far as pin cushion. I am really surprised as that was my only new lens so I spent far less time scrutinizing it than all the used glass I picked up. Now as far as the corner blur, your high angle sun provided a nicer sharp/contrast brick than mine but at 100% crop with both side by side its pretty efident that yours falls off much more from center to corner than mine does, especially to the lower left corner.

Since my ISP limits my web files to 10MB I need to find a free server tonight to drop this on and will then post a link here and PM you as well as up date this msg. Not sure how much tuning can be done to your lens but from the 2 shots at f8 i compared it definitely drops off faster in the corners than mine. When you get to compare you can decide if its worth xx weeks without the lens.

mtngal · 06-05-2009, 10:05 PM

Since you aren't planning on keeping your brick wall picture up indefinitely, try setting up a free 30 day trial account with pbase or zenfolio. I'd like to see yours, but in any case, thanks for letting me know that your copy is better than mine. I took some more of the same brick walls today, using a K100 - not much difference, though the blurriness isn't so obvious.

I actually find this good news, I don't mind sending the lens in now for repair. Our next trip isn't until fall, so I should have it back before we leave. I can live without it for the most normal things until then and I didn't particularly want to upgrade to a heavier, larger lens as I don't really need the extra speed and my camera bag is already too heavy with the lenses I already carry on a regular basis. Plus, I think I would have skipped the two 70-200 f2.8 lenses in favor of the DA*200, and that would mean a bigger camera bag, which I probably couldn't manage to carry comfortably anyway.

The pin cushioning isn't that big of a deal for me as I use this lens for walk-about, hiking and landscape, so there's not a lot of really straight lines. By the way, DxO's website has a place where you can request camera/lens combinations you would like them to measure. I've already suggested the K20/DA 55-300, for which they thanked me for the suggestion but said they didn't have it on their list. If more people request it, perhaps they'll add it.

Thanks again for helping me figure out what's going on with this lens.