Shooting in Aperture Priority Mode

So of course I recommend that people serious to photography learn to shoot in manual mode. It helps them to better understand the Exposure Triangle, the workings of their camera and locks the exposure giving you full control over everything. But once you fully know and understand all of that, the truth is 80% of the time I shoot; I am using one of the Semi-Auto modes; Aperture priority or Shutter priority. Today we’ll talk about shooting in Aperture Priority or AV mode in Canon and Pentax, A mode in Nikon, Sony andO lympus 

What is the basis of shooting in Aperture Priority? 

When shooting in Aperture Priority mode, you select the desired aperture (f/ number) and the camera will automatically set the correct shutter speed for that aperture and ISO you have selected. Since a good deal of what we shoot we rely on Aperture for the artistic decision of what we want our DOF to be, it’s a very often used mode. 

Shallow DOF

Deep DOF

The advantage of it over manual is; if we are in a fast moving situation or we are moving amongst varying lighting scenarios quickly, the camera will get us the shot without much dial twisting on our part. 

But, it’s not a free lunch and it still requires you to keep an eye on the one thing the camera is deciding for us: Shutter Speed. We still have to be aware of that shutter speed and if it is either fast enough to stop motion we may need to stop or simply just fast enough that we can hand hold the shot. The other side may be, is that shutter speed slow enough to show the motion we need show. 

In those cases we can make some decisions, we can either change our aperture: Open up the aperture to raise the shutter speed or close down the aperture to slow it. If it is not an option to change our aperture because we are seeking a certain Depth of Field (DOF), then our option is to change the ISO in order to get a correct exposure. 

What are some of the other things to consider when shooting Aperture Priority? 

When we shoot in manual mode we lock our exposure. It doesn’t change unless we physically change the settings. In Aperture Priority, we are locking the aperture, but the shutter speed is free to change. This could be a problem if you are someone that locks focus and then recomposes. If you have a person that in your composition is off to the side and you center them to lock focus most times you want the exposure to be correct on them. Now if you were to recompose and now say the sun or a bright sky is being metered by the camera in A/AV mode the exposure (Shutter Speed) will change and you may no longer have a correct exposure on your subject. 

We can do one simple thing to correct for this AND lock our exposure. Most DSLRs have an Exposure Lock button on them. On Canon’s it is on the back of the camera designated with a *, On Nikon it is designated by AE-L/AF-L and it does dual duties of Auto Exposure Lock and Auto Focus Lock. On Some Canon’s there are separate buttons for each but the truth is in the custom function menu of your camera you can choose how these buttons operate so read the manual well. 

 

Using Aperture priority to get your highest shutter speed 

I learned this little tidbit from my good friend sport shooter Jim “Homer” Cayer. Jim shoots a lot of sports and a good portion of that is “Under the lights” which may look bright to a sporting event’s fans but photographers know is some of the worst lighting conditions you can work under, especially if you don’t have a camera with great ISO noise handling at high ISOs. The other hurdle ( pun intended) a sports photographer has to jump over is that they are shooting a fast moving subject so they need fast shutter speeds to stop the motion of those subjects, hopefully 1/500thor faster. 

Stopping Action

So while you may think using shutter priority would be the norm because they can lock the shutter speed where they need. In reality it doesn’t always work that way, simply because you may not have enough aperture to open up far enough for the exposure. So while the camera will still fire, your image will be underexposed. You can tell if this is happening you will see the Aperture setting flash in the viewfinder. This is telling you there is not sufficient light.

 When shooting fast moving sports, that one more thing you don’t need to be watching instead of the action. So to counter-act this, it’s best to use Aperture priority, set to either wide open or the aperture you need for the DOF required. Then you can be assured that the maximum shutter speed will be used no matter what. You may need to up your ISO and you may even run out of ISO. But it will set the maximum Shutter speed for that combination of Aperture and ISO 

When do I not use Aperture Priority or any Auto mode for that matter? 

There are a few situations that I just won’t use AV/A or any auto or semi-auto mode. They just aren’t worth the little extra speed/convenience you may get.

They are:

  • Shooting with Flash and even more so with studio strobes. Shooting with flash you just don’t get the results or the consistency with other modes than manual. Shooting in the studio with strobes as your primary light source it’s just not possible in any mode but manual
  • Shooting in conditions where I know the meter is getting fooled. When the subject is Black or White that reflective meters get wrong.
  • Shooting in very low light situations that camera meters just don’t handle correctly and always over expose. Night Street shots or cityscapes at night.
  • Concert situations, where the meter either sees too much light because it meters a spotlight momentarily or gets fooled by the expanse of darkness surrounding the artist.

Now of course I could use Exposure compensation to make up for the meter getting fooled. But that still does not lock the exposure. So say as in this situation I was shooting this woman in a black outfit and then the next character was dressed in orange. The exposure would be thrown off in AV/A mode because now it had a more neutral subject. In manual mode the exposure would still be correct because the light had not changed, only the subject’s reflectance See the article on advanced metering for more on this. 

So as you can see there still are many instances where you can use Aperture Prioroty mode to  quicken the pace of your shooting and get the same results as manual mode. Some people think that isn’t true. BUT if you are relying on the camera’s meter and believe it is telling you the truth, the exposure will be exactly the same whether you chose Manual Mode or Aperture Priority 

How YOU choose to work, is up to you

 

PT

One Comment

  1. JBowman September 5, 2012 at 5:30 pm #

    Great tutorial Peter. Thanks

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