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Why I shoot in Av or Aperture Priority mode

09 Apr 2012 / 10 Comments / in blog

I hear it over and over again “real photographers only shoot in manual mode”, and every time I just shake my head. Yes there are plenty of photographers, real or otherwise that shoot in “Aperture Priority”, “Shutter Priority”, or even (gasp…) “Program” mode.

I, myself, shoot in “Av (Aperture Value, in Canon parlance)” otherwise known as “Aperture Priority” about 95% of the time. There are many reasons for this, but I would like to talk about the single most important reason as it applies to wildlife photographers.

Getting the shot!

Wildlife is unpredictable, and in the outdoors light changes very frequently. Often we have just a few seconds to get the shot, sometimes less, and often times with unpredictable light. This is not the time to be fiddling with and making gross aperture and shutter speed adjustments. If you do, chances are you will miss the shot, or get an image that is grossly out of proper exposure.

My process is to set the aperture appropriate to the image that I am looking to make and for the lens I am using, then set my exposure compensation to the middle or “0” position. With these settings I am ready to react quickly and trip that trigger at the exact moment, knowing that the exposure may not be perfect, but will be close; I call this my safe shot. Once I get this one, two or three, safe shots, I will then use the exposure compensation dial on my camera, WITHOUT taking my eye off the viewfinder, and tweak the exposure to achieve the look I am after. I will then fire off a few more shots, then “chimp”, that is, look at the screen on my camera and take a look at the histogram. At this point I may make some further adjustments and shoot some more, if my subject is still around that is…

You may be wondering, how do I know how to tweak the exposure without taking my eye off the viewfinder. Well I have gotten to know the metering system on the Canon system pretty well, and can reasonably predict how it’s going to react to an specific scene. This just takes time and practice; it also helps to have used Canon film cameras which did not have a screen and histogram.

I very often also hear how camera meters are dumb and that they try to expose everything to a middle grey…. that was true many years ago, any modern digital camera will have a very sophisticated metering systems on which camera manufacturers have spent millions of dollars and countless hours engineering. Modern metering systems are very smart indeed and they can, for example detect that you are trying to shoot something that is white, such as snow and make sure the snow comes out white, not grey. Many of these metering systems are color and scene aware and in the vast majority of cases will get you within a stop or two of the right exposure; in my personal experience within less than one stop.

I for one want to take as full advantage of all the tools at my disposal, and one of the most crucial to me is the meter in my camera.

As an example, take the image above of this Red Fox, this was taken on Mt. Desert Island in Maine while walking along the shoreline in search of a Bald Eagle nest that I had been alerted to. As I was walking along looking for the nest, I saw, out the corner of my eye, this fox sprinting along the edge of the water, mostly out of sight as the coast line in this area is very rocky. I noticed the direction the fox was running in, looked further ahead and tried to predict where I thought I may get an opportunity to make an image. I pointed my camera at that location and pre-focused where I thought the fox would make an appearance, I adjusted my aperture to give me some depth of field and waited for the fox. I was extremely lucky that the fox came out exactly where I had predicted and as soon as I saw the composition I was looking for I squeezed the shutter.

As you know, in any SLR, when you press the shutter your viewfinder goes dark as the mirror moves up to allow the light to hit your sensor and capture the image.

Well, my screen went dark as I pressed the shutter and when the mirror went back down and I was again able to see thru my viewfinder the fox was gone! I quickly checked the screen on the camera and saw that I had gotten the image! JUST ONE IMAGE. The cameras metering system did it job, and I would say that the image was dark by 1/3 or maybe 1/2 a stop, something that I can very easily correct in post-processing.

This whole event took place in all of 2-3 seconds!

If I had been relying on manual metering the chances that I would have gotten a properly exposed image would have been very slim, mostly because there would have been NO time for me to do any manual adjustments, I would have had my exposure for a bald eagle nest with the sky in the background, would have rendered this image way over exposed.

This Red Fox image is my second best selling image, and one of my personal favorites. Glad for “Av” mode.

I hope you found this information useful, and as always, if you have any questions or comments use the comments section below or you can reach me via Google+.