Last week we discussed how opening or closing the aperture of the lens on your camera influences how much light you let onto the camera’s sensor. If you have a lot of light, you close your aperture, if photons are rare, you open it. To get your exposure right, you need to get your aperture right. BUT: there is not only one correct aperture you can chose. The shutter speed, strength of your strobe and your ISO value all influence your exposure. So you have a certain amount of freedom when choosing your aperture. This is how you use it to create the image you have in mind:
Let’s Look at Two Gobies!
Take a close look at this photograph of a small fish, shot right in front of Salaya Beach Houses in the sand:
It is a shrimp goby, Vanderhorstia ambanoro, shot at f20. The high f-stop gave me a very wide depth of field. Almost all of the scene in the image is in focus: the sand in front of the goby, the goby itself, and the sand behind the fish. A shot like this works very well for ID books or for scientific documentation of marine fauna. We can see everything clearly.
Let’s look at another example, shot in Siquijor (that’s the island you see on the horizon when you are at the beach in front of Salaya):
This is also a goby, a mudskipper (Periophthalmus gracilis). It lives an amphibious life, skipping through the mangrove mud. This shot is hence not, in the narrow sense of the word, underwater photography. I would like to apologize for that 😉
You will notice that only the front of the face of the fish is in focus. Most of the mud around the mudskipper is out of focus: The depth of field is very narrow – I shot this image at f4.5. This kind of image works very well to draw all the visual attention of your audience to that small part of the photograph which is in focus. Shots like that often look really stunning and artsy. It’s up to you which kind of photo you want to take – the right aperture goes a long way in determining the photographic style your shots will represent.
Also check out how to pick the right shutter speed and ISO!
Photographic greetings from the Philippines! If you have any questions or suggestions, email me at firstname.lastname@example.org