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Old 31-03-2015, 12:53 PM
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ZeroID (Brent)
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Eclipse exposure ?

A bit of advice required.
I'm hopefully (weather permitting of course) going to try to get an eclipse time lapse this weekend but I'm having a little trouble deciding on suitable exposure settings.

I want to cover the event for 4 hours from just before contact point with the umbra (2215 hrs here ) to 0200 where it will have just started to exit the penumbra. ( I'm ignoring our daylights savings time shift here for simplicity ). In Auckland it won't be a total coverage, about 5% will still be visible. I'm hoping to run at 5 frames per minute which should get me about 40 secs of video ( @ 30 fps playing ).

My problem is that the light level is obviously going to vary greatly over this period but I'd like to capture the event and still keep the changing light levels consistent with actuality. Any compensating adjustments with ISO or exposure time would obviously show as sudden changes in the video.

My current guessitimate is to run at ISO 200 and about 1/30 sec exposure for the whole event. Early frames will be overexposed but the moon will already be almost inside the penumbra when I start but hopefully not too overdone and near totality exposures should have enough exposure to be visible. End will be over exposed again as it starts to exit penumbra.
Camera will be the 450D with a 2 x Barlow through the Lunt 102 F7 with BYE doing the control. I will probably run in bursts of 15 mins, ( 75 frames ) so I can pause for a battery change if needed partway.

Sound feasible ? Or would it be better to do some light compensation (ISO or expsure time) when necessary to maintain a more consistent level of light. I will run some early tests on the night to establish exposures at a good starting point.
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Old 31-03-2015, 01:37 PM
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rustigsmed (Russell)
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hi brent,

I did a timelapse last year (first half mostly cloud - and not properly aligned) https://www.flickr.com/photos/80336656@N07/15291875979/

I would recommend taking more photos - I did one every 6 seconds I think from memory.

I don't know if you can on the 450d but I was plugged into BYEOS but did not use it - I used the magic lantern intervalometer. the photos still are downloaded to BYEOS so you can see clearly how the images turned out.

the other advantage (and important in a dynamic event like an eclipse) is that you can tweak the exposure in between photos - simply by pressing iso or swivelling the exposure (which you can't do on BYEOS) without it interfering with the set intervalometer. I changed it constantly on mine to get a result through the clouds.

cheers

rusty
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Old 31-03-2015, 06:13 PM
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ZeroID (Brent)
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If I do 15 or 20 min runs I can tweak ISO or exposure at each break if necessary or pause the sequence. A few frames here and there won't show much difference. Probably do the exposure time, more discrete steps than ISO doubling.
I'd like to try and keep a consistent look to the changing light so I'd try to minimise any changes.
Thanks Rusty
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Old 02-04-2015, 02:51 PM
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rustigsmed (Russell)
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Quote:
Originally Posted by ZeroID View Post
If I do 15 or 20 min runs I can tweak ISO or exposure at each break if necessary or pause the sequence. A few frames here and there won't show much difference. Probably do the exposure time, more discrete steps than ISO doubling.
I'd like to try and keep a consistent look to the changing light so I'd try to minimise any changes.
Thanks Rusty
no worries Brent - I found it super easy on the 600d as you could change iso and/or shutter speed on the go with the frame rate being stable.

but i'm sure your method will work well, good luck and looking forward to the timelapse
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Old 02-04-2015, 03:22 PM
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multiweb (Marc)
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Last time I shot every 15s to 20s. Exposures ranged from 1/250s up to 5s during totality. I only changed ISO close to totality and I think it might have been ISO800. Otherwise it was 400 or 200 during the bright phase. I found shooting every 20s gives you plenty of time to refocus or recenter if you need to without interrupting the imaging. I got a bit over 1000 frames which gives you a nice length of video played at 25fps and also not too much to align and process.

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