I understand the concept of (auto-)bracketing, in general. And I understand that exposure bracketing is used for HDR and focus bracketing is used for focus stacking. But I am unable to imagine what DOF bracketing is or what its use could be. Any pointers?
DoF bracketing is essentially the same as focus bracketing, but rather than change the focus point/plane for each shot, you change the aperture to vary the depth of field.
Imagine you are taking a shot of, say, a cluster of cherry blossoms. You want the background blurred so you open the aperture right up. But this means only part of the cluster is in focus. So you stop down the aperture a little, which gives you deeper DoF, so more of the flowers are in focus, and so on.
Once you've got the shots you need to get the entire cluster in focus, you can put them all together in post - sharp flower cluster and blurred background. Bracketing in small increments means you can get a nice transition between the fore and backgrounds. If you just took one at f/2.8 and another at f/16 it would be tricky to get a natural looking result.
Depth Of Field bracketing is performed by taking several shots of same scene with different aperture (compensating change in exposure by adjusting ISO, shutter speed or lighting power).
Bracketed images are then used to have a wider selection of images to select the one with most appropriate depth of field in post. Or you could use masking and combine background from wide aperture shot with subject from tight aperture shot.
In general "bracketing" means taking a series of shots near the settings you or your camera has chosen.
There are two kinds. Exposure bracketing attempts to achieve the perfect exposure (sort of a shotgun approach) while the goal of Depth of Field (DoF) bracketing is to achieve the perfect composition.
Exposure bracketing involves the photographer or camera takeing an exposure at the suggested speed, aperture and ISO, then one or more exposures while varying either the speed, aperture or ISO setting. Usually, there is one or two over and one or two under the suggested by a full, half or third stop.
DoF bracketing can be considered part of the composition and artistic interpretation, something better left to the photographer rather than the camera. First, one exposure is taken at the suggested speed, aperture and ISO settings, and then one or more exposures are taken while varying the aperture and a complimentary change in speed or ISO setting that compensates for the change in aperture. So, two settings are changed not just one.
Canon cameras once had a function also called DoF bracketing that allowed the photographer to focus to select the nearest and furthest points they wanted in focus. This locked in that focus range by setting the aperture even while modifying the other two settings. I haven't owned a Canon or worked at a camera shop since Moses' time so I'm not sure if Canon still uses that terminology.
I do depth of field bracketing a lot. I shoot at different apertures to see what background I like best.
On the K-5, it's not that hard to use exposure bracketing as depth of field bracketing when using RAW. It's close to an ISOless sensor due to it's dark read noise— it's digital gain performance performance is near equivalent to it's analog amplifier gain. On other sensors, you will get somewhat higher noise at the smaller apertures than manually doing it. Here are the steps:
- Set the camera to take the overexposed shot first
- Go to shutter priority and turn auto ISO off
- Set exposure bracketing. Calculate what X.X EV stepsize and number of shots you want to get the apertures you want (too much and you'll hit f/22, which is a bit worthless)
- Use -EV compensation so the overexposed shot is at 0 EV, to not clip highlights
- Set your shutter to what you're comfortable with regards to motion blur and camera shake, if applicable
- Set your ISO such that your aperture is the widest that you want
- Shoot your images
- In post, set each shot +X.X EV (or use auto tone in lightroom)