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Old Feb 12, 2010, 5:57 AM   #1
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Default Testing the DA 55-300, opinions please...

I've finally received the DA 55-300 about which read some very positive user opinions from the forum. So, no wonder the minute I took the lens out of the box, I started testing it with such a joy : )
My initial impressions are; I'm quite fond of the colours and the corner to corner sharpness between the focal lengths 70-200mm. However thigs change especially @300mm, at which the center still remains sharp but the quality drops significantly towards the borders, which may sound typical of zoom lenses but above my expectations! I'm even considering to return the lens so would be happy to read your assessments.

Below are some crops from a picture of some distant brick building shot @ 300 mm ;F/8; iso 100 and using a tripod.


Left border




Right border



Center



The whole picture

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Old Feb 12, 2010, 6:21 AM   #2
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I can certainly see your concern, the differences from center to edge are obvious even with these on-line images. I have an of F 100-300mm f4.5-5.6 zoom that I should test sometime, although I suspect the result will be similar to this.
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Old Feb 12, 2010, 8:50 AM   #3
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Quote:
Originally Posted by Monza76 View Post
I can certainly see your concern, the differences from center to edge are obvious even with these on-line images. I have an of F 100-300mm f4.5-5.6 zoom that I should test sometime, although I suspect the result will be similar to this.
Thank you for your kind interest. I'd like to know about the result of your test. I really wonder if I have a defective copy!
My concern is; I often prefer off center compositions, but with an IQ such as this, I won't be able to do that anymore contentedly, at least, @300mm : (
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Old Feb 12, 2010, 9:15 AM   #4
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That looks like a de-centering issue. My lens does the same thing though maybe not quite as bad. I have decided to live with mine, and just enjoy the camera. Mine is only noticeable in a small portion of the lower left corner. You may want to send yours back, and get another copy.
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Old Feb 12, 2010, 9:16 AM   #5
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Hmmm - your pictures look very similar to the ones my first copy of the lens gave me - maybe not quite as bad as mine ended up being, but similar. They did sharpen up at the edges at about f16 or f20. Over time mine got worse and I finally sent it to Pentax Repair, who replaced the lens with a much better one.

I was just looking at the original, unprocessed street scenes I posted yesterday, especially the one of the welder, which were taken with the replacement 55-300, and there's hardly any difference where the fence is in focus (but not useful for comparison as it was taken at ISO 2000, so very noisy.

While I'm home and there's no brick walls handy, I'll take the 55-300 with me on a walk and see if I can't take something where everything is on the same plane, so you can compare.
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Old Feb 12, 2010, 9:32 AM   #6
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Hello Bahadir,
I no longer have them but, last year I took a number of test shots of a brick wall at work at different settings. While I did have some mild distortion it wasn't nearly as much as I see here. I don't know how you were set up for your test but, I would try it again and make sure your focal plane is parallel to the target both up and down and side to side, then try several different stop settings and focal lengths before you send it back.

I wouldn't part with mine although, sometimes it performs quite well and other times it can be rather disappointing. This lens seems to do its best work in well lit scenes.


... well, while I was slowly replying, two other good ones came in. I know Harriet has had some problems with her first one and is better able to guide you than I am so I'm glad she poped in.
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Old Feb 12, 2010, 12:12 PM   #7
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Bahadir, life is full of compromises, and the suitability of a lens depends on the use you intend for it. I don't take pictures of brick walls, so I can't comment on how my copy of that lens does under those conditions. I can only say that I have noticed no such problems in actual real-world use. You might check to see if the edges focus at a different plane than the center. This is not a macro lens that is calibrated for a flatness of field. You might have a defective lens or one with more curvature at the edges, but still within manufacturing tolerances for a lens in this price range - a different copy might give better or worse results. It may be possible that a curvature of field would be most noticeable at the longest focal length where the DOF is least - certainly at wider apertures, but if it is there, it might not be a problem in some types of shooting at all. I usually use mine at 300 for shooting birds, which are invariably centered for focusing and metering, and often cropped, so edge sharpness would less critical, and it serves my purpose well. I may use bench test results as a guide in searching for a lens, but I am more interested in how it performs in actual use than on the bench in static testing, so I also rely on user experiences, and they have been mostly quite favorable for this lens. You could have Pentax check it out, you could try another copy, or, in the end, it might not be the lens for you. Good luck with whatever you decide to do..
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Old Feb 12, 2010, 12:36 PM   #8
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Penolta, I fully agree. Mine also has a problem in the lower left corner, but in real world shooting, it is totally acceptable. I say enjoy the camera, for the money the lens is a good buy. If your happy with day to day use then keep it, if not send it back.
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Old Feb 12, 2010, 3:37 PM   #9
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@ Tony: Thanks for your assessment. Ah, learning to live with sth. is really not so much of an issue for me considering especially my recent copy of WA lens of 10-20 I reserved for interior architectural pictures and cloudscapes ; )

.................................................. ..................

@ mtngal: Thank you for the heads up Harriet! So, I should do sth before things go worse. Cracking up the f number somewhere around f/14 helps but, you know, then diffraction kicks in! Besides that makes me lose some very useful stops of light in terms of shutter speed. I've just seen your recent examples of street photography which quite appealed to me as usual : ) Thanks in advance for the comparative shot you mentioned.

.................................................. .....

@ Goldwinger: Thank you for your kind reply my friend! Actually I wasn't standing just opposite the building, which might be the reason of the distortion you noticed. Well, the first thing which surprised me with this lens was how prone it was for hand shake at 300mm without the OS, but the on board SR does a good job indeed!

.................................................. .......

@ Penolta: 'Bahadir, life is full of compromises...' Yea, which is doubly so of photography, starting even at the very basics of exposure, ain't it? Actually, I've been enjoying the good old K10D for the past three years with a single lens simply looking for ways of upgrading my abilities and taste : ) It was only when I started to feel the problems of real world use such as smudged foliage when I decided to shoot such a tasteless test shot with a hope of nullifying my concerns, but alas...I remember having to send back my 17-70 walkaround lens for three times so as to attain the present one I've been using knowing that I'll be the sole responsible for any failure in my compositions. As for my intend of buying the 55-300; shooting far off cottages, paths and ancient edifices while trekking...
Thank you heartfeltly for your kind reply which makes a lot of sense.

Last edited by bahadir; Feb 12, 2010 at 4:07 PM.
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Old Feb 12, 2010, 11:23 PM   #10
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I didn't really find anything that was flat, but I did have a great time snowshoeing and taking pictures with the several lenses.

While mine isn't perfect at the edges at 300 mm, it's not all that bad. I learned that it's not a good idea to compare it to one of my *300 lenses - there's a reason why they cost as much as they do (did) and why this one costs what it does. Rather than spending time with cropping etc. I just uploaded three full sized pictures. There's no flat surfaces in a pine forest, but I tried.

Full frame picture (reduced by zenfolio to fit here). It's not a beautiful picture, but I was pretty square to the two trees. It doesn't tell you anything about the center, though. I took it raw and then used Lightroom's default settings to convert to jpg and upload to zenfolio (there's a plug-in that will do that). Taken with the K-7 at f8 (exif should be included).



Full sized file at: http://mtngal.zenfolio.com/img/v5/p726760950.jpg

I hate taking test shots - so much can go wrong. Here I thought I was square to both trees, but it looks like I wasn't, or else the one on the left was larger than the one on the right. Also taken at f8.



The full sized file: http://mtngal.zenfolio.com/img/v8/p579751103.jpg

This is probably the fairest picture, though the subject isn't very good for telling about distortion. You'll get the idea I think.



Full sized file: http://mtngal.zenfolio.com/img/v4/p996710442.jpg

To give you an idea of what my first lens was like, you can see some of my pictures, they start with the one picture that convinced me I had a problem with it, includes wall pictures that I took with the old one, and then some walk-about pictures of the new one (but no more brick walls). http://mtngal.zenfolio.com/p691012471/e236d9aed

I'm going to be out of town for the weekend, and perhaps I'll find better subjects.
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