Depth of field and hyperfocal distance concerns when shooting cityscapes

[dikjenkins]

I will be shooting a series of panoramas from the 51 floor of a building in Manhattan. These panoramas will be taken both during the day and at night as well. Here is a list of my equipment and conditions:

Canon EOS 50D
Canon 28-135mm f/3.5-5.6 IS USM

I'm wanting to take in the cityscape in all directions from the top of this building, but my panoramas will probably span approximately 90 degrees each. I will shoot in portrait mode using Nodal Ninja panoramic head. The direction in which I shoot will be determined by the position of the sun.

I foresee that the closest building will be 300 feet away (across the street) and the furthest, infinity (the Manhattan skyline).

Being that the lens displays no DOF data I want to ensure that the city's buildings will be sharp and in focus.

Looking at the hyperfocal calculator found on the web I believe I should be shooting at f/8 and a focal length of 28mm. If I consider my "subject" to be 500 ft. away my DOF begins at approximately 16 ft. and extends to infinity.

I plan on bracketing my shots by 2 to 3 f/stops. I'll use High Speed Continuous shooting when bracketing. The bracketed sets will be post-processed using Photomatix Pro HDR software.

Questions:

1. Would you AF on the buildings initially and then switch to manual focus for the series of shots comprising the panorama?

2. Would you use the aperture and focal length I'm considering?

3. How would you achieve a sharp focus on the cityscapes after dark?

4. Would you use Live View mode to verify DOF and exposure levels?

5. Any suggestions to improve my chances of good results?   

[KeithB]

Unless you want depth of field effects, I would bracket with the time, not the f/stop.  I would think that f/8 is a good aperture - right in the sweet spot between lens distortion and diffraction effects.  You might stay away from "high speed shooting" unless you are using mirror lock-up, to prevent vibration.  I think setting the lens at the hyperfocal point should be fine since the subjects are so far away - so no auto focus is needed - especially at 28 mm.

[Bob Atkins]

DOF isn't an issue. Focus on infinity and you'll be fine. The difference between 500ft and infinity focus at 28mm would be infinitesimal.

I would switch to manual focus just in case the AF system screws up (it can).

I'd also set exposure manually in order to make sure that you don't get changes in the image brightness at the "seams".  f8 sounds fine. That should be small enough to minimize vignetting and maximize sharpness.

I'd use a good deal of overlap between the images since extreme edge and corner quality will be lower than center image quality. You don't want to be using the very edges of your images in your stitched panorama.

I think you should be OK with 28mm on a 50D. With very wide lenses (especially on full frame) there is some edge distortion due to the inevitable stretching of wide shots using rectilinear lenses. It's not a lens defect, it's an optical characteristic of such lenses.

[whizkid]

Why not just rent a Canon EFs 10-22 lens .  Used horizontaly it's horizonal field of view is over 90 degrees and vertically it is over 70 degres. Just one shot needed and DOF is a given.

[eriq samson]

Zoom lenses are not the best choice for clarity - a fixed focus 28mm would be much better choice here
(at best a zoom lens is a compromise with max sharpness in the middle of the range and issues at both extremes; then, too, they have to have more elements - pieces of glass - each of which adds a little blurriness while trying to correct larger issues

the 10 - 22 would introduce the infamous pincushion / fisheye effect; worse it is a zoom - see above

Should you have the money or someone rents them look into a gigapan - it is essentially a motorized cradle on a tripod that you set for size and number of exposures (for example 3 high by 30 wide) to stitch and it does the rest for you - the software included does the stitching. Their photo site gigapan.org has user submitted examples of pictures NOTE: it WILL do 360 degree images

[whizkid]

Zooms may bring compromises but good ones exist and Canon's 10-22 is such a lens. I would rate it's images as being as good or better than my Canon 28mm f/1.8 lens provides.