Is my copy sharp?

[TornadoFarm]

I went out to shoot with my 17-40 on my Rebel XT (time is very limited these days), and it seems to be soft on the left side, but not on the right....... I can't figure out how to post a full resolution, as photobucket only allows me to post 800 x600. Anyways, I'm fairly new here, and have been lurking for some time, and just wondered if anyone could offer some help and/or suggestions?

This is unprocessed, i just converted to RAW then resized. (The other photos I shot were not sharp on the left side either) Thanks....

[LightRules]

We really need to see a full-sized file of your images to see the border performance. If you are getting uneven side-to-side performance consistently, you've got a de-centering issue.

[TornadoFarm]

Thanks....... here is the full resolution

http://tornadolive.com/railroad3.jpg

Those trees on the far left seem way too soft.

[Tsmith]

Exposure Time = 1/15" at f/4 isn't a very good speed and aperture for determining sharpness.

[TornadoFarm]

yeah it was handheld.....but still, would it affect the left side and not the right? I'm a beginner here, so sorry for the questions.

[LightRules]

Originally Posted by TornadoFarm

yeah it was handheld.....but still, would it affect the left side and not the right? I'm a beginner here, so sorry for the questions.

The bottom line here is that it's hard to say from this one image. You need to look for consistent results of this uneven performance. Take some more shots, especially where you have a nice and flat plane of focus, shots with higher shutter speeds. Just report back after you've viewed more images that would make you sure you've got an issue.

[TornadoFarm]

Ok, will do, thank you for your help.

[Tsmith]

Do not get discouraged from this result as I think under the circumstances handheld especially it looks darn good. If testing at f/4 your gonna need a faster shutter speed to control image shake and you can't really worry about the corners at a wide open aperture, more so center sharpness and I see that in your image above.

Around f/8 is where you need to be concerned about edge sharpness.

[joegolf68]

The entire image looked soft to me.

[DenZ]

I think its soft due to shake, also, what focal length are you shooting at? I think the 17-40 (according to charts) is sharpest at 17mm. However, it should also be very sharp at 40mm.

Try shooting your 17-40mm lens box from about 8 feet away with a tripod on at f/4 with good lighting. Set focus to center point and focus on the large EF 17-40mm letters.

[cosworth]

Don't forget that contrast is how your eye sees sharpness.

Pick and image with lots of nice contrasty action on it. Shooting a grey winter day with nothing in the shot won't tell you.

Go find some nice brick or bare concrete wall and get someone stand there with some colours on. Big smile. We'll see sharpness in the corners fall off, sharpenss in teh eyelashes etc.

Best way to test this lens is a sunny day. Tripod. Set the lens to 20mm. AV mode and f/8. Lowest ISO you can get. Set the timer to 10 seconds and shoot. That way you eliminate %99 of the guessing:

Camera shake (tripod, shutter speed)
Contrast (sunlight)
Settings (focal length rule etc)
Natural lens limitations. (this lens is bland at 40mm)

Until then... who knows.