bramping where initial scene is dark - seeking advice

Started by pdirezze, January 02, 2013, 01:59:20 PM

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pdirezze

I'm taking timelapse photos (every 10 sec) from pre-dawn until post-sunset on my 600D. Right now I'm using aperture priority (F6) and letting ML2.3's intervalometer limit the exposure time at night to about 8 seconds.  I've set the ISO to auto (capped at 400).

I'm finding the night time stuff to be over-exposed.  I'd like to reduce exposure time at night to about a second or two.

I thought of using ML's Bulb Ramping feature, but I'm unable to provide the camera with a well-lit scene during calibration and the camera seems  to get caught in a calibration loop - at which point I have to turn off the camera.

Is there a way to fool the camera during bramp calibration?

Is there a way to somehow set a maximum exposure time that the camera's automatic settings could not exceed?

Any advice, suggestions?

tinyenormous

This is an idea I have had for a while. Feel free to test it out.

Create any number of different images with an average brightness. Either make it a flat %grey in PS, or simply shoot different brightness shots during the day.

Choose those as your sample image, then bramp away. You would need to have a good guess as for how far you want to fudge it, but I have faith in you  :)

tinyenormous

I don't have my t2i at home, and my 7D doesn't have bramping yet.
Here's a link to a bunch of grey card jpgs.

15grey.jpg
20grey.jpg
30grey.jpg
40grey.jpg
50grey.jpg
60grey.jpg

https://dl.dropbox.com/u/2343171/GreyCards.zip
Feel free to give it a shot!