This blog is my attempt to keep track of some of the things I learn along the way, with my Canon 7D, G12 and accessories. All images copyright Brad Calkins, not to be used without permission (or purchase). I do not attempt to monetize my blog, other than to promote my stock photo portfolio on Dreamstime.

Tuesday, May 20, 2008

Over on dtnguyen's blog, there was an interesting article on managing a telephoto to get sharp photos. Someone commented that the photo used as an example wasn't sharp, and there was a bit of a 'challenge' for a sharper photo from a telephoto. I started looking through a few photos, and although I have a lot of 'sharper' examples, they are not from telephotos, and are almost in every case a larger portion of the frame. I tried to find some that were about the same percentage of the frame. What I found was that almost all my telephoto shots (70-200 f/4) are a little less sharp than my shots from my 17-55 f/2.8. Here are a couple of examples of what I would consider typical sharp photos my lenses seem to deliver in REAL shots, either outside or in the 'studio'. Another way of saying that is that I don't think I get any sharper results in my telephoto shots (with a great lens that is very capable) than in the example enlargement.

This is from my 17-55mm at 55mm, stopped down a stop:
This is from my 70-200mm at 189mm, wide open at f/4:
Both are processed through Phase One Capture LE with no output sharpening. I didn't adjust any of the settings from the shot defaults. The top photo is a flash capture indoors, and the bottom is a sunlight/shade shot outdoor. I used a 1/250s shutter speed in the telephoto shot (plus IS), and I shoot on an APC sized sensor (Canon 20D).

I'd informally judge them to be about the same sharpness, but the bottom shot was a relatively rare find among my telephoto shots. Perhaps I tend to use the telephoto more often for 'action' shots whereas the shorter focal lengths get more use in controlled lighting situations (i.e. studio/flash). In any case I think it speaks to the need to take time to ensure sharp results from long lenses - the original point of the article.