Geoff, some comments below:
Quote:
Originally Posted by geoffsims
Colin - thanks for your insights. Do you really think it's feasible (possible?!) to use multiple cameras for the one sequence? Not only would you need identical optics, but surely with wide angle shots alignment would be a royal PITA?
Yes, probably not something for most people, but it is feasible and I have done it with 2 cameras (same body and lens - 24mm), where both cameras used the same shutter but separated by 4 stops of ISO. Worked nicely on a city HDR scene with moving lights - cars, etc. You need an intervalometer with Y-splitter or a dedicated splitter - http://forum.timescapes.org/phpBB3/v...hp?f=43&t=8612 , then mount the cameras side by side on a stereo bar...some bars allow for 3 cameras. Parallax is the biggest issue, so no close foregrounds.
I don't see any reason why the ISO or aperture would need to be modified (in general). For example, set the ISO to 400. As long as you can expose fast enough during the partial phases (?), this would make the exposures times quicker during totality.
I guess bulb ramping may be enough for the period 1 min -> totality. I'd like to see a published light curve for this period though. Do you know if any exist (in terms of EV)? With the latitude of RAW, it may be enough.
You could shoot, say, 1/16s and 1/2s exposures (with the intent of blending the landscape/sky portions) in quick succession not by changing the shutter speed (slow), but just sticking with bulb mode controlled via serial cable. From memory, bulb can be accurate to as fast as 1/30s (??? any ideas here).
Yes, bulb only accurate to about 1/30 s. You need a microcontroller though to achieve this. Via PC I think the limit is around 1/10 s (due to PC/windows timing accuracy). No idea if Mac is better or worse.
It still doesn't combat the issue of the ~5-10 minutes pre/post totality.
This is where I was thinking iso and aperture stepping would be needed. The entire sequence will cover around *16 stops, from sunny 16 -> totality (assuming totality = full moon light)
It could work out to be easiest to shoot three sequences:
1. Main partial
2. 5-10 minutes pre/post totality
3. Totality (incl +/- 1 minute either side)
And then cross fade them. Sequence #2 could be a fixed exposure, hopefully with enough latitude to allow smooth transitioning using LRTimelapse for example.
Yes, probably the best compromise in terms of difficulty vs reward.
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* I should say my thinking is based on the goal of tracking the light to yield an optimal exposure throughout. It's influenced by day-nights I've done and 3 lunar eclipses. May not be entirely relevant for a TSE.