As I mentioned in my last post, I bought an adapter so I could use my old (1979) Zuiko 50mm / f1.8 lens on my E-510. I’d heard that this combination was really bright, and thought that this would help in situations where I wanted to focus attention on a subject using a tight depth of field (i.e., subject in focus with everything in the foreground and background out of focus).
So I put “shorty” on the ‘510, went out in the yard, and practiced on some early (for Colorado) spring flowers. Here’s one of the pictures I took, of some puschkinia that are just starting to open up (click on the image to go to its Flickr page):
Did I mention that “shorty” gives a very tight depth of field? I originally tried to take this picture at f/1.8, and couldn’t get more than a small slice of the flowers in focus at a time. So I consulted this handy online depth of field calculator and found out what I would have known up front if I’d done my homework: at close range, you have to really close this lens down to get any useable field at all.
The lens will focus down to about about 18″ — at this range, using f/1.8, the depth of field is a bit over 1/8″. The image above was taken with the lens closed down to f/8, yielding a depth of field of about 0.7″ — tight enough for good effects, but still big enough to be useable for small subjects.
To spell out the raw artistic power that is an f/1.8 lens, here’s a quick table of depth of field as a function of focus distance:
| Distance | DOF |
| 18″ | 0.16″ |
| 3′ | 0.67″ |
| 10′ | 7.7″ |
| 30′ | 5.9′ |
| 100′ | 73′ |
| 250′ | 1207′ |
As you can see, things open up quite a bit once you get some distance from your subject!
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