Photodigitary

I recently had a superb question from a reader about using a telephoto lens for close ups. First, telephotos can be outstanding for close-up and macro work (there is a difference between the two, one is closer than the other, but for purposes of this blog, I am going to lump them together as the ideas for using telephotos are the same). Several things are really great with the telephoto up close:

1. You gain a lot of control over your background. Because of perspective changes, you are enlarging your background, which means a slight movement of the camera will usually give a big change in background color and tone.
2. You can gain a very nice blended background because it is much out of focus (your camera position relative to the subject and background has a lot to do with this).
3. You gain some great selective focus effects that can really set off a subject.
4. You can step back from a wary or sensitive subject, or you can work farther away from a “dangerous” subject that could bite or sting.

There is a disadvantage to using a telephoto for close-ups and that is the limited depth of field (which is also an advantage when used right). You have to be very careful about your focus point.

How do you get a telephoto or telephoto zoom to focus closer? While many zooms have close focus settings, and a few standard telephotos do, most do not focus close enough. Extension tubes, achromatic close-up lenses and tele-extenders all work to help you get better close ups. Extension tubes are probably the most useful. They are relatively inexpensive and are simply an empty tube (with connections to the lens electronics) that fit between the lens and camera body, allowing the lens to focus much closer. How much closer depends on the focal length and the length of the tube. You will find, for example, that the same extension tube will make your zoom focus at different distances when set to different focal lengths. Extension tubes add no optics, so image quality is generally very high, but this is going to depend on the original lens. Some lenses do great up close, some do not (and this is not necessarily about the price of the lens — some high-end pro lenses are so geared toward focusing at moderate to longer distances that they do not do well up close). The only way to know this is to try the lens. One advantage of extension tubes is that they will work with every telephoto lens or zoom you have. They will reduce light some to the sensor.

Achromatic close-up lenses such as those from Canon (250D and 500D, which work on all lenses — you just need the right filter size), Hoya, Century Optics and some others, screw into the front of your lens and work great. They don’t always let you get as close as extension tubes (especially if you buy a set of three tubes for a lot of extension), but they do work well. Again, results will vary depending on the lens. And they only fit one lens filter size, so you may have to use filter ring adapters.

The tele-extender fits between camera and lens and magnifies the focal length. It doesn’t actually let you focus closer, but magnifies the subject from the old close-focusing distance of the lens, so you do get more of a close up. They do cut light significantly and often look best when the lens is stopped down from the maximum aperture. Some lenses work great with extenders, some do terribly.

With my Olympus gear, I have used the 50-200mm extensively for close-up work, including with the Olympus extension tube and also with the 1.4x extender. I think it is fantastic for that purpose. It does a wonderful job. The biggest problem for sharpness with it is not the lens itself as I think it is wonderfully sharp, but camera movement.

Camera movement during exposure is a problem for using all telephoto lenses up close. When you are using a telephoto up close, you are focusing on a small area with magnification so camera movement is intensified. How can you know that camera movement can be the problem? When you see two photos, the same basic composition and settings, one is sharp, one is less sharp, you have a big clue. Then when you look closely, look at the specular highlights (bright spots from the sun or other bright light). If you see specular highlights that are tiny lines (from the movement) rather than spots, that is camera movement.

This entry was posted on Wednesday, November 4th, 2009 at 8:46 am and is filed under Digital Photo Techniques, Digital camera techniques, Equipment thoughts, nature photography. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.