Aperture and exposure bracketing

I have occasionally used exposure bracketing, sometimes for sunset scenes with the sun in the shot or, on only a handful of occasions, for botanical shots with a flower against the sky. Mostly though for contre-jour botanical shots I expose for the highlights and do deep shadow lifting. On reflection, it might be better if I used exposure bracketing more often for both these types of shots.

On the other hand I have used aperture bracketing a lot, always for botanical scenes. For me, one of the issues with botanical shots, especially flowers, is trying to get a pleasing balance between the amount of the subject that is in focus and the look of the background, both of which change as the aperture changes. Before capturing a shot I can't tell how that balance is going to work out for a particular aperture. Often, with micro four thirds or APS-C, it may be around f/8 to f/13, but from time to time it can go as far as f/4 or f/16, and occasionally right out to f/22 or, very, very rarely f/2.8. Trying different apertures and reviewing them on the LCD slows down the flow of a session, giving it a very different feel, dulling my creativity. And in any case it can be ineffective because it is difficult to judge accurately from what appears on the LCD, especially in bright sunlight, and even more so if the capture has been underexposed to protect highlights.

Starting with the G80 and now with the G9 I can use aperture bracketing; with one press of the shutter button I can have exposures all the way from f/2.8 to f/22, and I can then take my time choosing which to use when viewing them in subdued light on my PC, if necessary after some initial processing to lift the shadows. I have found this to be very effective for my purposes, in terms getting results that I like the look of and also in terms of keeping capture sessions moving at a good pace.

There is a downside to aperture bracketing that needs to be weighed against the advantages. The ISO is constant during an aperture bracket sequence. That means that the shutter speed doubles in length for each stop reduction in aperture. I therefore need to use an ISO that will give a tolerable shutter speed at the smallest aperture that I am likely to want to use. Quite often that means using ISO 800 or sometimes ISO 1600, and even then the f/16 and f/22 exposures may sometimes be too slow to avoid motion blur. That means that if I use one of the shots with a more typical aperture then the ISO will be higher than I would have set it if I had been shooting a single shot with that aperture. So, using aperture bracketing, ISO is suboptimal a lot of the time, which can make the processing more complicated than it would have been for a lower ISO single shot, and my degrade the perceived image quality in some cases.

On balance I thought the advantages of aperture bracketing outweighed the disadvantages, and so I used it a lot with the G80 for botanical subjects, at first mixing it with single shots and then eventually using it most of the time without using single shots.

This changed when I got the G9 and soon started using focus stacking most of the time for botanical subjects.

I have never tried aperture bracketing for invertebrates because getting the maximum DoF coverage of the subject is my primary concern for invertebrates.