Hello Colin. Long time no see... about 18 years 11 days and 8 hrs this Nov isn't it?
Interesting thread Geoff.
Colin & Geoff wrote :
"By the way, I have not seen any light curves, but will have a look.
Thanks. I had a quick look but couldn't find anything in terms of EV."
I have an eV light curve here:
http://joe-cali.com/eclipses/PAST/TS...tse990811.html
It's about 3/4 way down the page and measured in eV. I took the dome off a Sekonic incident light meter and pointed it at the sky not straight at the eclipse so it's not a measure of exposure but of ambient light levels from the sky and eclipse falling on the sensor. If you want the dome on incident light values, subtract about 2eV from the readings.
Auto exposure works quite well with a very wide angle lens. The sky in umbra is pretty evenly lit. Dial in a bit of -ve compensation (0.5ev - 1eV) or else the sky will come out 18% grey.
You could also try to dial in -3eV then use an rfc to pull up the shadow detail. The -3eV will give you some mid-outer coronal detail.
Foreground detail can be brought up by stacking and masking in the landscape from numerous "under exposures."
When we were on the beach at Tatakoto, I ran the timelapse camcorder at 1 frame per 30s for about 2 hrs which gave about 10 s of footage covering that period. I started it as soon as I could get the camera set up on your tripod after we arrived. About 20 mins before the eclipse I put in a fresh battery and changed it to 1 fps for 40 mins. gives about 80s clip of the time around totality. I probably could have slowed down the first 2 hrs to 1 frame per 10s to give 30s of footage but then the evaporating rain off the lens wouldn't have been as interesting.
I think to be kind to a viewer and keep their attention you need to time it so that the ingress partial and total are about the same length of time and the egress partial is about half the length of the other two.
I am very definitely trying to record umbral passages and I'm not so concerned with coronal detail which I capture in close up in other ways. I know that Geoff is trying to capture inner, outer corona, sky and land.
The camcorder timelapse of the 2010 eclipse and another captured on a film SLR can be viewed on this page :
http://joe-cali.com/eclipses/PAST/TSE2010/joe.html
and another of the 2008 also with a film SLR can be viewed on this page :
http://tinyurl.com/9zm637o
Even though the landscape is dark in these cheap machine jpg scans off colour neg film, the landscape can be easily brought up by stacking two landscapes and adding the pixels. Joe