+1/-1 EV exposure ramping

[agour]

Hey,

I'm wondering if it's possible to implement a new mode for timelapse shooting. As you know, sunsets/sunrises have extreme exposure changes. The easiest way to shoot them right now, is to shoot in manual mode, and wait for the meter to be 1 stop under (or over) exposed. When that happens you adjust the exposure to bring it back to 0EV.

It's a pain in the arse to manually do, so it would be great if we could automate the function. I know there is a mode in ML that gradually ramps the exposure, but it's not as useful as this.

You would be able to input what values you want to ramp to change the exposure, so could set any combination of shutter speed, aperture, ISO. Also being able to set limits on each would be great, so don't use a shutter speed longer/shorter than XX.

Any ideas if this is possible, or how difficult it would be to implement? I have absolutely zero coding knowledge unfortunately..

Cheers
-agour

[dmilligan]

You are describing almost exactly the module that I have created. More info here:

http://www.magiclantern.fm/forum/index.php?topic=8431.0

Just download the lastest nightly and the .mo file linked in that first post and add it to the modules folder.

[dmilligan]

Also see this:

http://www.magiclantern.fm/forum/index.php?topic=5705.0

I've gotten some great results with AutoETTR combined with my module.

[agour]

From what I understand in your description, your module just ramps values based on the time/frames that you set?

The issue I have with that is that it's mainly guesswork trying to calculate times and so on. If you start it to ramp aperture too early, the whole sequence could be ruined.

I've not tried auto ETTR yet, but will give it a go soon

[Danne]

Dmilligan. Youre module is really good. I, m  curious how you would apply autoettr to your ramping module? For instance, how would you apply it going from day to night? Are you using  xmp sidecar files aswell?

[guilhermemartins]

@agour
I think there is also a "how to" about - ettr timelapse - that you will find very helpful. http://www.magiclantern.fm/forum/index.php?topic=5705.0

[dmilligan]

@Danne,

I ramp the aperture and WB with my module and aettr sets the shutter and ISO. You can also have aettr only set the ISO and ramp shutter as well with my module.

Yes, I use the XMP sidecars and process in Bridge/ACR and AfterEffects. I usually have to go through and manually fix some of the sidecar exposure decisions that ML post deflicker made (either a quick transient change in the scene threw it off, or it failed to run for a particular frame and no sidecar was generated). This is pretty quick and easy with ACR in Bridge. Unfortunately adobe did not include the multifile ACR mode that's in Br, in AE. Why they didn't is beyond me, but everything you do in Br is saved in the sidecars and applied by AE.

ML deflicker usually tries to pull up the exposure too much once it is fully dark, but aettr hits it's limit and doesn't change the expo settings, so it's easy to just modify the exposure down of all frames taken after full dark is reached.

[Danne]

Thanks a lot. Also noticed a couple of sidecars has to be adjusted in post but the deflicker ratio is very good, almost 100%.

"ML deflicker usually tries to pull up the exposure too much once it is fully dark, but aettr hits it's limit and doesn't change the expo settings, so it's easy to just modify the exposure down of all frames taken after full dark is reached."

The exposure pull up when going from dark to light or other way around is sometimes to strong. Do you experience that as well or do you get smooth ramping?
Still, thanks a lot for sharing your work. Gonna try out your workflow next time