I was down in the mountains last week and my wife Christal and I visited the Banff Springs Hotel. Inside they had an amazing fish tank. While waiting for Christal to use the bathroom, armed with my camera, I took the opportunity to try and shoot some tropical fish. I had never tried shooting fish in a tank before or ever tried shooting through glass. The camera has no troubles with auto focus through the glass although I am sure it still does take away from some clarity in the final image. Following the fish wasn't too difficult since they were moving slow but would get scared easily by the lens. I shot 10 or so photos before I moved on but thought this one was nice and vibrant and I was able to keep the clownfishes eye in focus. TIP: It is always important when taking pictures of anything with eyes, that you always focus the picture on the eye and then re-compose before pressing your shutter all the way. It was especially important for me to capture a sharp eye since I was very close to the subject and was shooting with an aperture of 2.8. 2.8 means the Iris of the lens opens very wide when taking the picture which does two things. 1. It allows more light to enter the lens so you can use faster shutter speeds which helps in low light. It is also very nice for portraits or any time you want a very short depth of field. This means that only what you focus on will be sharp and the rest will begin to blur very quickly. Take a look at the background coral in this photo. It is very blurry and has almost no detail. This helps the subject, in this case the fish, to pop out and attract the viewers eye to what you want them to see. When you shoot something like a landscape, it may be important to use an opposite aperture such as F22. This will make what is right in front of you and the landscape in the background all in focus. Of course this is the basic idea and there is some other technical tricks behind these effects but perhaps I will visit these on a different post :)
TECH INFO: Shot with Canon 40D 24-70 L series lens at 48mm, ISO 1600, 1/100th sec, F2.8. Cleaned up in LR and border added in PS. This pic is not by any means 'sharp' or what I would call great quality but I like to push the limits of my camera in low light. It is more challenging and a test to see how steady I can hold the camera and gently press my shutter button. But on the other hand, at 1600 the quality is superb and has acceptable levels of grain.