Something Fishy? Check Your ISO

Today’s Post by Mildred Alpern

The first image that I took was blurry and I knew why. My ISO was too low and less sensitive to the light, resulting in too slow a shutter speed. I had entered an aquarium that was very dim in its passageways. The constant maximum aperture on my Olympus M. Zuiko 12-100mm f/4 IS Pro lens was not bright enough in this interior space. I needed to boost the ISO in the darkened hallways lined with fish tanks to get faster shutter speeds.

I wanted to freeze the darting movements of the fish as they swam about, so I went to an ISO setting of 3200 and hoped the images would not be noisy. They were not. I could have reduced the noise in Lightroom if I chose, but it did not seem necessary. With this ISO high setting I was able to freeze both the meandering glidings of the fish and the watchful figures peering through the glass barriers and obtain sharp images that were not grainy.

Once outside, where the seals romped and enjoyed a feeding time, the high ISO was unnecessary. I reduced the ISO to 640. The day was overcast with an even light. I reviewed the first image on the LCD screen and it looked fine. Happily, the zoom lens worked well for the varied candids in indoor dim and outside brighter light as I walked about. It is a good idea to check all settings before shooting, something I often forget to do.

All images were shot with the Olympus E-M5 Mark II and the Olympus M. Zuiko 12-100mm f/4 Pro; the girls observing the fish @ 16mm, ISO 3200, 1/60, f/4, +2/3EV; the fish alone @ 16mm, ISO 3200, 1/100, f/4, +1/3EV; seal feeding time, @ 44mm, ISO 640, 1/800, f/4.


Mildred’s books Winter Garden and Seedhead and St. Agnes Public Library Exhibit are available from MagCloud in print or digital form at most affordable prices.