Memory is cheap. Some shots are rare – especially moon alignments and other ephemeral events. The worst thing that can happen besides a horrible accident or equipment disaster is to leave the scene of a shot-of-a-lifetime and discover every shot is seriously over or under exposed. Of course out of focus is right up there in the kick yourself list.
Film photographers have been “bracketing” shots since the medium started because unlike digital, film people can’t be sure of what they captured until they process the film. Some events transpire quickly enough that even digital photographers can not (or should not) take the time to “check” their exposures. Solution: bracket.
And what about those tricky lighting situations where the foreground is bright and the background is dark – or vice versa. Solution: bracket.
And then there are those situations were a slightly longer exposure – or a slightly shorter exposure will get a more pleasing result. Solution: bracket.
There are two primary ways to bracket shots – set up Auto Exposure Bracketing (AEB) in your camera, or do it manually. There is a third way too: do BOTH. And there is a fourth way described below. In every case I describe I use a tripod. If you’re not using a tripod for this kind of shooting you might as well smear vaseline on your lens since you’re making your life needlessly harder.
What is a bracket?
Bracket means to vary some element of the exposure to capture the possible range of light of interest to the photographer. Usually the best thing to bracket around is the exposure length because varying the aperture may change the depth of field (though that could be interesting), varying the ISO may change the noise characteristics of the result – also potentially interesting.
To catch the best exposure with minimal fumbling I set my camera in Auto Exposure Bracketing mode. As a Canon shooter I generally have it set to -2, 0 and +2 exposures . There is so much latitude in RAW data that it doesn’t make sense to me to shoot in fractional stop or one stop increments. -2 and +2 mean two-stop less and two-stops more exposure than the starting settings. In real numbers if my starting exposure is 1/100 of a second, the -2 exposure will be 1/400 of a second (1/2 of 1/2 of 1/100) and the +2 exposure will be 1/25 of a second (2 x 2 x 1/100). For some scenes -2 to +2 is NOT ENOUGH. In fact, it’s often not enough when you have a bright object like the moon and darker objects like fading light on a landscape.
When Time is Critically Important – Frantic Mode Bracketing
When the moon is setting or rising, I may have mere seconds to get the exact alignment I want. Before the exact moment arrives I have already taken several exposures to be sure I am in the right “ball park”. I look at the histogram, check to see if anything has blown out and select a starting exposure that seems about right. Sometimes I get that starting exposure by just letting the camera pick it. I then switch to Manual mode and dial in the exposure that the camera determined for me.
On my Canon cameras in Manual mode the top wheel adjusts the exposure time. My frantic shooting sequence will then go like this: set the best guess exposure with +/- 2 bracketing. Shoot. Spin the wheel about nine clicks to the left. Shoot. Spin the wheel about twenty-one clicks to the right. Shoot. When I say shoot, I mean the WHOLE bracket, not just one shot. Two ways to shoot the whole bracket are to:
- Set the camera into continuous exposure mode and hold down the shutter button (or better yet, shutter release button), or
- Use the 2-second delay mode which will automatically fire off all three shots in the bracket.
I go nine clicks to the left because I have my camera set to increment in 1/3 stops. Nine clicks is therefore 3 stops less exposure. Is it important that it be EXACTLY 9 clicks – no, not very. By shooting in this way when done I will have shots at -2,0,+2, -5,-3,-1, +3,+5,+7 Arranged in order the shots span: -5,-3,-1,0,1,3,5,7.
It also happens that “nine clicks” is about two “flicks” to the left for me. While twenty one clicks to the right is four “flicks” and a few more clicks for good measure.
Why Don’t I Just Set My AEB to -5 to +7?
There is no camera that I know of that can do this. Notice how I have -1,0,+1 in the mix, but all the other elements are increments of 2? Yeah, that doesn’t exist in any camera (yet), but some Canon models can go 2,3,5 or 7 shots in the range with up to 3-stops difference. Some Nikon models can go to 8 exposures at up to 2 stops (or EV as Nikon calls them). And there is another reason, too. While I have to manually intervene in the process, I can prioritize the shooting order. I tend to favor shooting the longer shots toward the end, but I can reverse that if I think the longer shots are the more important ones.
Method Four – Tell the Camera Where to Meter
What I described earlier is what I’d refer to as “frantic” mode. When every second counts because the scene is changing. If my scene is a bit more static, for example when I’m shooting for an High Dynamic Range (HDR) I use another trick. I make the camera do the work to get the right shots. Imagine this scene: a bright sunset or sunrise, with dark but important foreground elements. Here I need the sky to be on, the landscape to be “on” and some reasonable transition from one to the other to make any HDR processing work well.
On my Canon I set my camera to AV (aperture priority), I use the Live View feature with zoom. By turning off auto-focus a rectangle appears on the Live View. I can move this rectangle around and zoom in 5x or 10x. To get the sky exposure right I’ll move the rectangle to the brightest part of the sky, zoom in so it’s all or almost all bright sky and fire. The camera meters on the rectangle in this case – so my bright sky exposure will be right. If there is a lot of gradation in the sky color, I may find a “moderately” bright sky and repeat. I then find a mid-tones area in the shot, move the rectangle there, zoom in and fire again. Lastly I find a shadow area – move the rectangle, zoom in and fire. In each case I’ve allowed the camera to select the exposures – oh, and I usually have AEB on, too.
I can do 9 exposures in 1EV steps max on my Nikon D700. This is usually enough for outdoor scenes, but not usually interiors with bright windows, and certainly not extreme scenes like looking into the moon at dusk. For all the rest–if I’m on a tripod anyway–I use a Promote Control. This has made bracketing scenes like real estate interiors a whole lot easier for me. Not cheap, but if you do it enough it’s worth the investment…
In an ideal world I could cover the entire range I’d want with say 4 exposures. Minimizing the total number of exposures matters when shooting a scene that is changing pretty rapidly like a moonrise or set through a telephoto lens. 7 or 9 exposures would just take too long. I can imagine doing this whole operation very easily with e.g. CamRanger. I’d click on the bright thing in my scene, the dark thing, and tell it to shoot a bracket which spans the scene in reasonable increments of up to 2 stops. Indeed, a clever enough camera or camera controller could calculate it all and shoot automatically based on the scene and live-view data.