Ok so I shoot basically one thing....real estate. I am in the market for a new camera so I borrowed a friends canon 50d. I have been using a Rebel xti and been getting good results but I want to upgrade. I took some exteriors today and they came out like crap. Very soft! I shoot with a tripod because i use the AEB functions and layer all of my shots so it wasnt hand shaking. I have a canon 10mm x 22mm lens, set the iso at 200 and f-stop at 6.3. I really dont understand much else and could really use help.
Rodger Cicala over at LensRentals.com would suggest that in fact your lens is not soft, or at least you only have a 3-7% chance of that being the case. You said that you used this lens previously on a Rebel XTi body with good results, and now with a new body the 50D you receive poor results. Rodger contends that this is due to slightly different characteristics that each body can have.
A lens may be fine on one camera and not another. A camera may do fine with one lens and not another.
Another great quote to note
Until recently, wide angle lenses tended to be soft in the edges and corners and people just accepted it. Recent lenses are so much better that differences from one side to the other became noticeable (the difference between sharp and soft is more obvious than the difference between soft and softer, apparently).
It is possible that you have a miscalibrated lens or body, or even both, but a respected(in my opinion) professional with a great deal of experience believes that it is due to the differences between bodies and lenses. A suggested solution would be to send the lens and body combination into Canon and the can properly calibrate the two together.
More could be determined if you could provide sample images. If you find this reply to be the best that you receive, please mark this as the accepted answer.
The 50D supports manual calibration for lenses; therefore it is possible that your friend had it calibrated for their lens, which might be far enough off to impact your shots. (This is assuming your friend has the same lenses, otherwise the 50D would have used Canon's calibrations.)
A few other possibilities, but we we really need to see some example shots in order to give a valid observation:
- What sensor was used for AF? Center? One of the others? Did you adjust them, or use what your friend had used? (Which may not have been right for your shot...)
- Had you gone from an air-conditioned environment (like a car, house, etc.) to a humid environment? Lenses react very badly to sudden changes in environment, and they can take a long time to acclimate.
- Did you use Mirror Lockup? (This helps reduce vibrations when shooting longer exposures.)
- Did you compare at pixel-level or at the same relative size? Your XTi is 10mp vs 15mp. Technically not that large of a leap, but any focus or lens issues that were minimized on the XTi are going to be more present at the pixel-level on the 50D simply because each pixel-sized sensor expects the light to be focused better. I suggest reducing the size of your 50D images to the same size as your images taken with the XTi and then seeing if things still look soft. (This is only a guess. I could have seen it being an issue going from, say, 8mp to 18mp, but I doubt this is your issue. But it's worth throwing out there.)
- Did you have anything else on the lens that you haven't used before (like a UV filter or Polarizer. A bad filter can do very bad things to an image.)