Author Topic: New Hand Held Bracketing Script  (Read 585 times)

garry23

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New Hand Held Bracketing Script
« on: October 01, 2019, 10:04:11 PM »
I’ve decided to update my hand held bracketing script by making better use of the ML bracketing capability. The script is best used with WA lenses.

The script is ideal for use in high dynamic situations such as cathedrals and where you can’t use a tripod.

The script takes the min shutter from the ML ETTR. So set this up.

All you need to do is set the ML advanced bracketing to two frames, bracket type as exposure, EV increment to 3 or 4 Ev, according to your camera, sequence to 0 + ++, and ISO shifting to full. The script works best if your base ETTR ISO value is low, eg 100.

The script allows you to select a triggering button, but you can also do a long half shutter, for more than 3 seconds, to trigger the script. I personally prefer the half shutter approach.

You can add an addition delay if you wish, ie if using a button.

Finally, you can ask the script to show you the button/key value, if you don’t know it. But switch this off after you know the button value.

The script will run in LV or non LV mode.

Once set up, the script should be used as follows.

1. ETTR to set the base exposure. I use SET to Trigger the ETTR.

2. If the base exposure is less than the min shutter, as set in the ETTR menu, then three brackets will be taken: at the base shutter and base ISO, the min shutter and the base ISO, and at the min shutter and base ISO + 3 or 4 Ev.

3. If the base exposure is the same or greater than the min shutter, the only two exposures are taken at the min shutter and base ISO, and at the min shutter and base ISO + 3 or 4 Ev.

Process your brackets as you wish.

Finally, as usual, watch out for conflicts with other scripts, ie switch these off if conflicts observed.

I’ll write more about the script when I get a chance, including some examples. For now, you can download it from here https://gist.github.com/pigeonhill/96ac84ea5f1435b056120b4d03884425

garry23

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Re: New Hand Held Bracketing Script
« Reply #1 on: October 02, 2019, 07:37:00 AM »
A quick note to explain the bracketing logic used in this script.

The base exposure, at low/base ISO, will cover the highlights.

The min shutter exposure, at the low/base ISO, will give you the highest photon capture.

Finally, the min shutter at ISO plus 3 or 4 Ev, eg at 800 or 1600 ISO if the vase ISO is 100, will give you your ISO invariant bracket.

For more info on ISO invariance see https://clarkvision.com/articles/iso/

For example, the 5d3 becomes ISO invariant around 1600 and shooting at higher ISOs than this is not needed, i.e. just adjust exposure in post.

As I said in the first post, when I get a chance I'll give a few examples.

Danne

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Re: New Hand Held Bracketing Script
« Reply #2 on: October 02, 2019, 08:02:22 AM »
Suggestion:
Post a video of your workflow explaining from start to finish about this script. Bet it will attract way more attention this way.

garry23

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Re: New Hand Held Bracketing Script
« Reply #3 on: October 02, 2019, 08:14:23 AM »
@Danne

Good suggestion, but I think you know my response   :D

I write my scripts for my use, but freely share on the ML forum.

As I said in the first post, I will write a bit about using the script: most probably on my blog: and maybe even a video or GIF, as you say.

Of course, any ML user can ask me a question here  ;)

Finally, I will say that, from my perspective, the ML forum appears highly biased towards videography developments. I'm not sure anymore how many photography-only people, like me, are around. This is not a criticism, just an observation.

Cheers

Garry

garry23

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Re: New Hand Held Bracketing Script
« Reply #4 on: October 02, 2019, 07:12:43 PM »
Have added some additional control over the max ISO that the script will use.

Float means the Ev set uplift will be used, relative to the base ISO.

800, 1600 or 3200 means that the max ISO will me restricted to the ISO selected, eg 1600 or 3200 is good on a 5D3.


garry23

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Re: New Hand Held Bracketing Script
« Reply #5 on: October 02, 2019, 10:44:32 PM »
As promised, some insight into using the script: http://photography.grayheron.net/2019/10/hand-held-bracketing-script-version-2.html

BTW I removed the option to trigger off the buttons - too flaky.

Danne

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Re: New Hand Held Bracketing Script
« Reply #6 on: October 02, 2019, 11:08:55 PM »
Had an attempt to test this script out but failed. Tested on my own ongoing eos m build, seems to need some auto ettr stuff. Anyway. Checked you examples on your site. Trying to get a grip of what you are saying. Couldn´t. But then I view you images and I can´t really see why the advanced bracket itself wouldn´t achieve what your script is doing on top of advanced bracketing? Question. If I expose for highlights and then take one or two additional images to capture shadows and then enfuse these two or three images. How would this differ from going thorugh your script? I am very curious. What´s the benefit here?

garry23

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Re: New Hand Held Bracketing Script
« Reply #7 on: October 02, 2019, 11:36:55 PM »
@Danne

All good questions.

Using 'just' ML advanced bracketing would be the same as my script in many cases. However, the advanced bracketing will not cover all situations.

In advanced bracketing you bracket from a base exposure and there is no way to limit the max ISO, i.e. the bracketing is controlled only via the set Ev lift. If your base bracket is, say, ISO 400, and you have requested a two bracket, full ISO at an Ev lift of, say, 4, your highest ISO bracket will be at 6400.

You could play around with using the half ISO option in the advanced bracketing, but again you need to ensure your base exposure is fit for the advanced bracketing settings.

My script uses the advanced bracketing, but attempts to add a little logic, that ensures you get the 'best' bracket set, i.e. max photons and an ISO limited to your max, i.e. 3200 on my 5D3.

Horses for courses  ;)

Danne

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Re: New Hand Held Bracketing Script
« Reply #8 on: October 02, 2019, 11:51:42 PM »
@Danne
In advanced bracketing you bracket from a base exposure and there is no way to limit the max ISO, i.e. the bracketing is controlled only via the set Ev lift. If your base bracket is, say, ISO 400, and you have requested a two bracket, full ISO at an Ev lift of, say, 4, your highest ISO bracket will be at 6400.
Ok, so it´s max iso. Just tested and restricting max iso in canon menu to 1600 works and it won´t push 6400 iso, or is it bypassed by advanced bracketing? Exposures seemed the same although it said 6400 and limit one was 1600. Just tested fast here...

garry23

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Re: New Hand Held Bracketing Script
« Reply #9 on: October 03, 2019, 06:47:42 PM »
@Danne

Quote
seems to need some auto ettr stuff

Doesn’t need any ETTR stuff. So should work, unless the Lua module you have is ‘old’.

Latest version seem to work really well, ie script runs in the background and is simply triggered by a 3 second long half press, from an exposure set for the highlights.

Script handles advanced bracketing settings and switches advanced bracketing off after brackets are captured.

Cheers

Garry

garry23

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Re: New Hand Held Bracketing Script
« Reply #10 on: October 04, 2019, 09:05:16 AM »
Added in a menu item to set your own half shutter delay time, between 1 and 9 seconds.

garry23

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Re: New Hand Held Bracketing Script
« Reply #11 on: October 04, 2019, 11:22:41 AM »
BTW just to reiterate that this script is an extended and convenient way to make use of the ML advanced bracketing.

It exploits the fact that Canon DSLRs are iso invariant above a certain value. Look here to find your value  http://www.photonstophotos.net/Charts/PDR.htm

This is also a good read on ISO https://clarkvision.com/articles/iso/

As I said in the last post, you can dial in your own half shutter delay, ie to deconflict from other half shutter delays.

The script will always give you the ‘best’ hand held brackets, as long as your base exposure is set for the highlights and you have set the ETTR min shutter. But note you don’t need to ETTR to set your base shutter.

Finally, the script’s use case is hand holding a WA lens, ie wider than, say, 30mm.

garry23

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Re: New Hand Held Bracketing Script
« Reply #12 on: October 06, 2019, 03:10:12 PM »