Estimate the distance of that part of the scene that you want the sharpest and manually set your lens for that distance using the distance scale. In most cases this will be infinite or close to it. Your depth of field will be best if you set your aperture to f11 or f13.

Frans Waterlander
pixographer/printer

Frans Water

I was using a Canon 20D with EFS 18-55mm. There is no distance scale on the lens to use as a guide. I think I had the lens apeture set pretty far open since I was using a long exposure already for the moon lighting. I guess I should have stopped it down and increased the exposure to get the dof. I don't know if this lens focuses beyond infinity, but maybe I should have set it to the limit and let the DOF take care of the rest?
Thanks, GH

Blurry photos might have been caused by the long expsoure itself. The moon rises and wind will cause ripples on the water and tree branches to sway.
See if natural motions are not the cause of your problem.

Next time you could auto focus on infinity and other points in the daytime and note what the lens' positions are using masking tape and pencil marks for instance.

Frans Waterlander
pixographer/printer

Right; this is a good idea but the fact you might have to do it is a major problem with autofocus lenses. For the current challenge I think the best thing is to find the hyperfocal distance (based on format/aperture/focal length) and set the lens to that distance by focusing on something that is well enough lit. There are various dof calculators on the web, and your camera maker's website probably has lists. One good site is http://www.dofmaster.com/dofjs.html

I use fcalc, a downloadable little utility that will give you about anything you want to know: depth of field, angle of view, hyperfocal distance, etc. etc.

Frans Waterlander