Using automatic exposure lock as an alternative for manual exposure

[Ed Erkes]

I thought I’d share an exposure technique described in an article I’ve written for the most recent Nikonians Ezine ( http://www.niknians.org/ezine/eZine51.pdf ). The technique may be of interest to wildlife photographers who, like myself, understand the advantages of using manual exposure when light levels are constant, but REALLY don't like using it. I much prefer the flexibility and ease of aperture priority mode when making creative exposure adjustments. Too many times I’d be in manual exposure mode when photographing wildlife and something would happen suddenly and I'd want to get either a faster shutter speed or more depth of field quickly. I'd end up screwing it up because I'd be attempting to rapidly rotate both aperture and shutter speed dials at the same time in opposite directions to maintain proper exposure.
The article describes a way to program Nikon cameras so that, in an automatic exposure mode such as aperture priority, you can lock the exposure value with the press of a button and the exposure value will remain locked until either the button is pressed a second time or the camera is turned off. With the exposure value locked you can easily make adjustments to depth of field or shutter speed by rotating only a single dial. Below is an excerpt from the article’s conclusion.
1. Automatic Exposure Lock provides the same key benefit of manual exposure--the
ability to set an exposure that the camera cannot override --yet it retains the speed
and flexibility provided by automatic exposure modes. Aperture and shutter speed
remain linked. When the photographer selects one, the camera automatically selects
the other to maintain the same exposure.
2. The third exposure variable, ISO, is also linked in AE Lock. In aperture priority
mode, a change in ISO will change the shutter speed to maintain the locked exposure.
Similarly, in shutter priority mode, a change in ISO will result in a change in
aperture to maintain exposure.
3. The use of AE Lock keeps photography simpler. One doesn’t have to worry about
switching exposure modes or using camera dials differently. I work in aperture
priority mode at least 98% of the time. Instead of having to switch over to manual
mode to “lock” exposure, I simply press the exposure lock button. Keeping things
simple helps me avoid making mistakes in the heat of the moment of fast action.
I think this advantage is particularly important to the serious amateur (such as
myself) who photographs sporadically – usually on week-ends, more or less frequently
at certain times of the year, with occasional lay-offs of several weeks.
4. Automatic exposure modes also enable you to be always ready for sudden photographic
opportunities. At the start and end of every shoot, I try to make sure my
camera is in aperture priority mode, exposure compensation zeroed, with matrix
metering and ISO 400 selected. Whether my camera is slung over my shoulder or
on a pillow on the passenger seat of my car, these camera settings allow the opportunity
to get an image by quickly bringing the camera to my eye and shooting.
In manual exposure mode, you would have to adjust aperture and shutter speed
to null the meter before shooting.


Note: Only the top-end Canon cameras can be programmed this way.

[John Davenport]

I kid you not I came here this morning to ask the similar questions. I do the same as you sometimes. I shoot a 1d mIV you can also learn the camera and given light and use exposure comp. I think either way its the some what the same as M mode depending what you are looking for. This is only true for most of my situations because i shoot wide open 2.8 or 5.6 depending if i use the teleconverter 2.0 mk III. I know there are many variables to this but I can make the proper changes to this practice. In decent light i use around 400 iso. In less light I have to bump the iso up where my shutter speed will be up to the point that i want have motion blur. And of course I and looking for the blinkes. Some say focus and recompose it don't work that way but if I use AL servo focus and recompose it locks the exposure at the focus point. I only use evaluative metering. I know you can use m mode and get some more control but this works for me in most situations.

John D

[Charles Glatzer]

Ed,

AEL works beautifully, and quickly, especially when combined with a familiar meter pattern where comp can be determined and added to the base exposure ahead of time.
I use the AEL function with Av and Spot Metering when the light is frequently changing, as I can define the pattern to a specific tonal value and apply exacting compensation.
Example; I can use Av or Tv adding + 2EV comp spot metering off the white chest of a penguin in changing light and my exposures are dead on. The problems comes when
using Eval/RGB metering with Auto modes and the subject size changes relative to the background, requiring you to change the compensation to maintain the same exposure.

The new Canon 1DX will allow you to use the AEL, locking in the exposure until you tap the button again. No longer will you need to re-AEL after a burst.
Now that is a useful function to be sure, and I for one am greatly looking to employ this feature in practice.

I will say it again... Meter Patterns determine exposure, Priority Modes change the variables.

Best,

Chas