There are a couple of specific challenges to taking good photographs of critters in an aquarium: namely the water and the glass. Water affects light (and hence photography) in a couple of ways. Firstly, water absorbs the different wavelengths of light at different rates. The warmer colours are absorbed faster than the cooler colours. Red is removed first, followed by orange and yellow. This is why underwater photographs that are taken without artificial lighting typically look very blue. The warm colours disappear rapidly—objects viewed through even a couple of feet of water will look noticeably “cool” in colour. Secondly, water is much denser than air and readily holds tiny particles in suspension. Unless it is carefully filtered or distilled, even water that looks clear to the eye will hold plenty of suspended material. As a result, the farther away an object is underwater, the lower the visible resolution and contrast will be.
Although the loss of warm colours isn’t likely to be much of an issue for photography in a home aquarium, loss of resolution due to suspended particles will be. In my home aquarium I have sand, wood, stones and a lot of plants. The inhabitants include three species of shrimp, three species of snails and three species of fish [three of each, isn’t that odd?] all of which are moving around, picking through the sand and plants and generally stirring things up. I have 2 filters on the tank and change water on a weekly basis so the water looks clear enough to drink. But in reality I can see a significant loss of resolution in a photo of an object more than a few inches inside the tank. The obvious solution is to try and photograph subjects that are close to the glass.
The challenge is that the glass of the aquarium also causes problems: light sources and light coloured objects may show up in photographs as reflections; and “stuff” on the glass will reduce resolution (and may be visible in the final image). [“Stuff” usually means dirt and fingerprints on the outside and/or algae and diatoms growing on the inside of the glass]. The solutions are to keep the glass very clean (inside and out), focus on subjects that are not too close to the glass so that any “bits” on the glass will be thrown well out of focus, and to place the lens as close to the glass as possible (to avoid reflections).
In summary, the best aquarium photos will be of subjects that are close to the inside surface of the glass—but not too close—taken with the lens close to the outside of the glass. In other words, aquariums lend themselves nicely to close-up and macro photography.
Below is a series of photos I took yesterday of a pond snail (family Lymnaeidae) crawling along a strand of hornwort plant (Ceratophyllum). I realize that this is the second post in just over a week that featured pond snails. But I must admit: I really like these cute little critters. Besides, I thought this was a fun little series of pictures.
This little snail crawled back and forth along this strand of plant two or three times before it found a suitable way off. I said they are cute, not smart.
The technical stuff:
Camera: Olympus E-620 digital SLR
Lens: Zuiko 35mm macro
Settings: manual exposure (F14 @ 1/125 sec)
Lighting: On-camera flash