Loss of detail in the corners

I've mentioned this problem on the website before, and now figure it's time to solve it.

My everyday setup is a Nikon D700 with Tamron 24-135 zoom lens. The Tamron is a CPU lens.

I'm noticing major distortion on the lower corners of my images. It looks like motion blur! I don't know why this is happening and I need to try the same thing with a few other lenses (I also have a Nikon 24-120mm zoom), but I'm always had good quality photos with this Tamron. I've always felt that it produces better pix than the Nikon zoom.

Here is an image with the problem. The top of the posted image shows the full area in question. It was taken at f10 so that isn't the issue. The bottom sections are from the middle, the approximate 1/4 point from the right, and the far right in that order: you can see a very distinct loss in detail there, like motion blur.

Any ideas what this is?? I had a Nikon D200 before and never noticed this issue. I wonder if it's an issue between the 700 and the Tamron lens.

G

http://www.gregbulla.com/Photography...t1_Problem.jpg

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Originally Posted by GB1

Any ideas what this is?? I had a Nikon D200 before and never noticed this issue. I wonder if it's an issue between the 700 and the Tamron lens.
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You never noticed that with your D200 because the D200 only uses/see through the central part of the lens.

As AE pointed out, its because teh D200 uses only the sweet spot of the lens (of an FX lens anyway). The variety of imperfections in the corner of a full frame image is typical (vignette, detail loss, distortion, etc), especially on the wide end of the zoom. If you zoom in 5-10mm, you'll most likely improve the corner quality quite a bit. This is the cost of full frame, you're now using the lens' entire image circle! Some lens have particularly better corner performance than others. another way to deal with it is to simply frame your image slightly loose.

You have a Tamron 24-135 AND a Nikon 24-120? Why? lol.

I think you received exactly the right answer to your question. I will probably always stick with the smaller censor due to the fact I can't afford the more expensive full frame lenses and also enjoy the benefit I get from the crop factor as far as the telephoto end, Jeff

Same stuff I saw on my Nikkor 18-35 on film. Full-frame cameras really require top-shelf glass. The above posters are 100% correct.

Sorry to rub salt into the wound but the edges show not only reduced definition but also light falloff. Notice how the edge extract is darker than the section taken from the center?

I've been through the reviews and the 24-1xx lens that I would put on a full-frame camera is the very latest Nikon 24-120.

Hmm.

This is really SAD. I know that some lower end lenses suffer some loss of detail and darkening in the corners, but this is not really a lower-end lens, nor has just a little loss of quality - it's pretty severe in my book.

I will have to do some experiments w/ it against my Nikon zoom @ 24mm. Also, since I don't recall every having this issue with my Nikon F100 with either lens, I will do some experiments with that and closely examine its output. It sure seems like the problem, but I need to make sure.

Charlie, I got the 24-120 Nikon awhile back and was never happy with its sharpness. I finally came to conclude that it just wasn't a very sharp lens, and online forum posts showed a lot of folks unhappy with it. I got the Tamron and noticed an improvement. I was going to sell the Nikon but then bought the F200 DSLR, so keep one zoom on my digital and one on my F100 (it's a bit of a pain swapping the lens in the field, especially if the wind's blowing a bunch of junk around).

Many thanks for the analysis !!! I will post my results here before too long.

G

I think ALL zooms that start in the super/ultra wide angle spectrum exhibit this to some degree. Faster, wider ones on full frame cameras are going to be the most pronounced.

I had the Canon 16-35mm f/2.8L mark II and got rid of it because it was so bad on the 5D.