Exposure Variations
by William Lulow
This is a typical “thought process” on exposures and how to tailor them to your particular photographic needs. The family is currently on vacation in Florida and the grand kids just love to play in the pool. I decided to make some images of them playing and swimming. There was going to be a lot of action involved, so I knew I needed to use a fast shutter speed. I also decided to use my medium telephoto lens because I wanted to do some tight shots of the kids with some limited depth-of-field. Remembering that longer lenses limit D-O-F naturally, my lens selection was kind of pre-determined. So, I had some requirements at the beginning. Besides a fast shutter speed, the shallow depth-of-field was necessary so that the kids’ faces would stand out against the pool.
The first exposure setting I changed was my ISO. Again, I knew I wanted to use a fast shutter speed to be able to stop any movement the girls were doing, so the greater ISO setting would allow me to use that faster shutter speed. Here’s the first example:
Exposure for this image was ISO 200, f/7.1 at 1/250th of a second. Here’s another:
So the exposure was enough to stop the movement, separate the kids’ faces from the background as well as provide correct tonal range. This one was made at ISO 200, f/6.7 at 1/250th of a second. Most of the lighting conditions here were the same for quite a few of these images, so it was really easy making them. Here’s yet another one in the series:
The exposures for these pictures were dictated by my need to capture the girls in action.
In each of these shots, I used my “back button” focusing technique and a center spot light meter reading using the meter built into the camera. In each case, exposures were within 1/3 of an f/stop from what the meter indicated. I sometimes underexpose my frames intentionally to provide a bit more saturation than normal. The images were all designed with the same purpose in mind – to make good closeup photos of the kids that would stop any action and be very sharp.
Over the course of several years now, I have experienced that higher ISO numbers, within reason, have not had any bad effects on overall image sharpness, especially when digital lenses are used stopped down a few stops. In the days of film we called this “sharpness in grain,” meaning that although some images were a bit grainier than normal, the sharpness of the image was still preserved. I have routinely achieved very sharp images with ISO settings of 1000 or even 1600. When I shoot musicians in nightclubs with stage lights, I often set my ISO to around 2000 or even 2500. Here is one of those results:
This is an image of well-known singer/songwriter/guitarist, Peter Calo in a very dimly lit nightclub. ISO 2500, f/6.5 @ 1/125th of a second.
So, don’t overlook what higher ISO settings can do. They can give you the freedom to shoot at faster shutter speeds to minimize camera movement as well as use lenses on smaller aperture settings.
