Sharp, in focus night scene with Christmas lights

[dikjenkins]

I've been somewhat successful at capturing a fairly large landscape containing buildings and palm trees adorned with Christmas lights. However the image is not as sharp as it can be. Because of the vastness of the scene I've chosen the Canon EFS 18-55mm AF lens. The camera is the EOS 50D on a sturdy tripod. These are night shots therefore it is difficult to achieve a good focus. I've tried focusing on the farthest building with its big Orvis sign but the majority of the scene is not tack sharp. I've tried focusing on a crisp object about 1/3 of the distance into the scene hoping I'd nail the hyperfocal distance but now Orvis is blurred. See my attached image please.

Here are my average settings: f/22, 1.3 sec., ISO:800, Evaluative Metering. Self-timer: 2 sec. and some degree of (-) Exposure Compensate to handle the lamp post lights.

[Bob Atkins]

Three things come to mind.

First, you're going to see some degree of diffraction blurring of the whole image at f22.  It shouldn't be too bad, but I suspect that in the sharpest areas you'll get better results at f16.  For more on this see http://www.bobatkins.com/photography/technical/diffraction.html (I need some better example images on that page, but the theory is good).

Second, you may simply be expecting too large a DOF. It may not be possible to get everything (at all distances) in sharp focus. Stopping down increases DOF of course, but at the expense of diffraction blurring. Stopping down past f16 may well increase the sharpness of the areas at the limits of the DOF, but it also blurrs the parts of the image that are at the focus distance. If you're at 18mm, you should have enough DOF even at f16 or f11.  However if you're at 55mm, you may be running into DOF limits.

Third, the 18-55 isn't a bad lens, but it's certainly not Canon's sharpest, especially when you get some distance from the center of the field.

Remember that the limits of DOF are the points at which the image is not unacceptably blurred. You don't get razor sharpness across the whole DOF range. For more on this see http://www.bobatkins.com/photography/technical/dofcalc.html

[dikjenkins]

I think your answer is right on target Bob. Thank you so much. I'll go back and shoot the scene again at f/16 and post the results. I spent a good amount of time since your reply re-examining my original, full size image, and I've noted that the text on the signpost directly in front of me (near left in the photo) is sharp, and the "Orvis" sign on the building 600 feet in the distance is also fairly sharp. Let's see what f/16 does for me. I've noted the focal length of this image is 41mm. I also have a Canon 28-135mm f3.5-5.6, AF, IS lens. Perhaps I'll shoot the same scene with this lens if I can take it all in. The focal length should lessen some.   

[Bob Atkins]

If you're in the same spot and use the same aperture, it doesn't matter what lens you use since you'll need the same focal length to get the same angle of view.

Using a shorter focal length will give you more DOF, but of course you'll get a different nagle of view too.