HDR/Bracketing - Shutter/Aperture/ISO

Started 3 months ago | Discussions thread
Garry2306 Regular Member • Posts: 108
Re: HDR/Bracketing - Shutter/Aperture/ISO

Bill Ferris wrote:

sakibnaz wrote:

Hi there ... generally we do HDR/backing by changing ShutterSpeed. What are the use-case of Bracketing by ISO or Aperture?

Will it be useful doing Bracket by blending ... like Under-expose by Shutter and Over-Expose by ISO?

STOP -1 (Adjusted by Shutter Speed)
STOP 0 (Base Exposure)
STOP +1 (Adjusted by ISO)

Exposure is the same in your base and +1 shots. You've not overexposed the +1 shot. It's made using the same exposure by ids rendered 1-stop lighter.

Any benefit of it?

In my experience, ISO bracketing is of limited usefulness. It doesn't offer any improvement to raw image quality, which is largely determined by the total light used in the making of a photo. ISO has no direct influence on that. It's the amount of light available in the scene, f-stop, and shutter speed that determine how much light is captured during a shutter actuation.

Exposure remains constant in a set of photos bracketed by ISO. In most circumstances, a photo made at a certain ISO and selectively lightened in post will look no different from a blended set bracketed by ISO. F-stop bracketing might have some usefulness in creating a composite image having a deep depth of field. That goal can also be achieved by using the same settings, focusing at different distances within the frame, and blending the resulting images.

I've read a few posts by folks who shoot ISO bracketed sets because of a workflow preference over processing a single image. Hey, if a person prefers one workflow over another and gets good results, by all means, use the workflow of your choice.

Bill as I suggested in my response, I think ISO bracketing has a place when handholding, eg in a location that forces you to handhold and has high DR.
One caveat on this is what camera system you are using, ie does it have a full ISO invariance from the base ISO, or, like my Canon 5D3, say, ISO invariance only kicks it at around, say, ISO 1600 . Hence I will limit my ISO shooting to 1600 on this camera and it’s different on my other cameras.

As long as you have captured sufficient photons, you will not get much out of ISO bracketing, if shooting with an ISO invariant camera system. With a camera where ISO invariance starts at a higher ISO value, ISO bracketing when handholding may have some benefits, ie allowing you to blend in the cleaned up ISO image with you base image, to address shadows.

Finally, I sometimes ISO bracket for the wind, ie when focus stacking, where I wish to ‘freeze’ wind motion on near parts of the scene .

Bottom line: understand how your camera responds to increasing ISO and use this knowledge to decide when to ISO bracket, if at all.

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