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06-05-2009, 11:52 PM   #16
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Agree, I think there is something wrong with your lens. I have done lots of brickwall with my copy and never remember seeing that much distortion or softness in the corners. Its late I will continue this latter and have a finale IMO for you.

I found a test pic at 210mm and it needed -3 for the distortion imtheguy is right on the money. The softness is not there in my pics however only 'very' slightly. So I am not adding much to what imtheguy is allready doing. I can only backup his findings with my copy.

Send it in IMO and get it fixed, its well worth it...


Last edited by jamesm007; 06-06-2009 at 12:12 AM. Reason: Found a test pic
06-06-2009, 02:05 AM   #17
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Ok, pbase file limit is also 10MB but Zenfolio came through for me for next 14 days. Here is my brick in the wall. Keep in mind I was between thunderstorms so my pic lacks that nice direct sun contrast yours has that really shows off the sharpness. I also did not have things quite leveled but did not want to do anything in PP before posting. Once leveled in PP, the pin cushion correction is just like yours.

full size download here ---> http://stilltheguy.zenfolio.com/img/v1/p113864861.jpg

DA 55-300mm, f/8, 210mm. 100 feet or so to wall, 1/125 shutter, ISO 100, tripod leveled as best i could with bubble level and 90 deg to wall

Zenfolio account will be closing soon so brickwall may be gone without notice. In the future if anybody needs full-size brick wall shots to re-open this issue just pm me and I will repost pics else where.

After analyzing the wall, I had to run out and get a quick critter pic just to remind myself that for my purposes I can't see the pin cushioning or corner softness. Still don't like it though. But after this pic I feel better.

Last edited by imtheguy; 06-25-2009 at 08:27 PM.
06-06-2009, 06:42 AM   #18
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Good thing I don`t need to take pictures of brick walls. Cause all those shots, as far as pin cushioning, look like the way my 55-300 performs.

Cheers. Mike.

No brick wall, a brick chimney, only thing avail.
f8, 210mm , 1/350, ISO 800, under heavy cloud cover. About 50' away.

Last edited by Ex Finn.; 12-29-2013 at 10:40 AM.
06-06-2009, 08:21 AM   #19
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critters

After analyzing the wall, I had to run out and get a quick critter pic just to remind myself that for my purposes I can't see the pin cushioning or corner softness. Still don't like it though. But after this pic I feel bette

I felt better too, imtheguy. I think some bricklayers might be the ones at fault here.

Here's another critter shot with my nice new 55-300!

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06-06-2009, 08:52 AM   #20
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Maybe the 55-300 does not like brick walls.
Works lot better on airframes.

Cheers. Mike.

Last edited by Ex Finn.; 11-11-2014 at 05:52 PM.
06-06-2009, 09:18 AM   #21
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Yep, fusilage looks straight enough to fly to me.

I have been happy with it on most everything, even as my primary closeup with a Raynox stuck on the front as I dont own a true macro. But this doesn't impact MTNGAL's issue which in my opinion is the moderate edge softness, particularly the lower left corner assuming the camera was reasonably perpendicular to the wall. The word "distortion" threw me, probably all of us, in the beginnning.

MTNGAL, I hope you send it in for adjustment for your peace of mind and so the rest of us can find out exactly what Pentax can do about the observable difference between your sample and mine. Please let me know how it turns out.

edit - had to add a point. you can see from my critter shot, which is my TYPICAL usage, why I would never notice corner/edge softness. DOF is my friend and everything but my subject is blurred anyway if I can get as close as I want. No, not a zoo shot.
06-06-2009, 09:26 AM   #22
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Mike,

You are right. I didnt bother measuring the adjustment on your pic since it looks just like the wall pics. Thanks for increasing our statistical sample size by 50%!

06-06-2009, 09:53 AM   #23
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My main use for the 55-300 is airplane pictures, so little distortion is acceptable.
I feel that the lens is pretty good value for the money.

mtngal, do let us know of the outcome, if you send the lens in for repair.

Cheers. Mike.

Last edited by Ex Finn.; 06-06-2009 at 10:33 AM. Reason: Deleted irrevalent rambling.
06-06-2009, 10:23 AM   #24
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QuoteOriginally posted by jamesm007 Quote
Agree, I think there is something wrong with your lens. I have done lots of brickwall with my copy and never remember seeing that much distortion or softness in the corners.
The Photozone review states:
The Pentax lens exhibits negligible distortion at 55m. In the 100-300mm range you can expect a medium degree of pincushion distortion which may be visible at times in field conditions.
The amount of distortion in the brick wall photos posted here seems similar to that shown in the graphics on the Photozone site. I won't comment on the sharpness question, but it looks to me like for this lens there's nothing abnormal about the distortion people are seeing.
06-06-2009, 01:07 PM   #25
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Thanks for all the sample pictures of the brick walls, especially imtheguy's full sized wall. It does look like the edge blurriness of mine is significantly worse than everyone else's examples, so as soon as I finish this post, I'll print the return form and post it off to Colorado on Monday. I'll let you know what happens.
06-25-2009, 07:26 PM   #26
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As an update to this thread - today I arrived home to a box on my front porch. Pentax replaced the lens with a new one. I promptly went outside and took a real uninteresting picture of the rough wood siding on my house. What a BIG difference! This lens is reasonably sharp even wide open, and by f8, there's little difference between the center and the edges, like imtheguy's samples. Tomorrow I'll take a walk and see what it does on something real-world, but right now, I'm delighted.
06-07-2014, 03:23 PM   #27
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Hello. I have this problem with my da 55-300. i turn the lens to 300mm, focus at that mm (auto or manual). then if i turn the lens to any wider position (280, 250, 2oo mm or everywhere else), the subject goes out of focus. So far i l knew that in a zoom lens if you focus on the telefoto end, it will keep being focused at all wider positions. Has enyone else seen the same problem? thanks


06-07-2014, 07:46 PM   #28
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As far as I know the lens is varifocal, like most zoom lenses today - meaning the focus changes as you zoom. That's a completely different problem than the OP experienced. You should always focus at the focal length you'll be using. You should be thankful if you have a copy that's sharp across the frame at all focal lengths, and not worry about having to refocus when you zoom.
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