2 August 2017 at 10:34 am #573803
Just a quick check not having imaged a total solar eclipse before. I shall be using a 400mm telephoto and a Canon 100D camera. I have a Thousand oaks filter for the front of the telephoto. In order to image Bailey’s beads/ diamond ring I assume the filter should be removed, with an exposure of about 1/4000 sec at f11. Is this in the right ball park? For totality I am looking at bracketing shots from 1/2000 down to 1/4 sec, keeping the aperture fixed at f11. Any hints, tips or suggestions would be most welcome.
Tom Moran2 August 2017 at 10:37 am #578412
Forgot to mention I would use 400 ISO setting.
Tom Moran2 August 2017 at 8:37 pm #578415Grant PrivettParticipant
My copy of Covington’s book suggests that at f/11 and 400ASA/ISO, an exposure of about 1/250th is about right for prominences and 1/15th for corona. Well worth bracketing from 1/1000th down, but how are you mounting the camera? Driven? Undriven. Fixed tripod?
Handheld and without autofocus and stabilisation, the suggested minimum exposure for a half decent photographer in the film days was 2/FL where FL is focal length in mms or, in this case, 1/200th of a second. But a tripod and cable release should improve on that by nearly a factor of 10 I think.
For 1999 I went from 1/1000th to 1/20that 400ASA. Pics were a little soft, but usable.
But really we need an expert like Nick James who has seen total eclipses more times than most. 🙂3 August 2017 at 5:20 am #578418Nick JamesParticipant
These days I prefer to operate my DSLR in HD video mode with manual exposure and the ISO fixed at 400 I then adjust the exposure during the eclipse to suit. I use a Megrez 72 and x2 Barlow operating at around f/13. I tend to take my filter off around a minute before second contact and adjust the exposure so that I get correct exposure on the inner corona which is visible even before C2. This leaves an overexposed photosphere but generally works well then for the diamond ring and prominences. You can see an example of this at around 0:25 in to this video. For Baily’s beads You would leave the filter on until C2 and use the same exposure that you use for the thin crescent.
During totality an example exposure for prominences, inner corona and chromosphere at f/13 is around 1/1600 at ISO800 which is what I used for the attached image. This is a raw image just scaled to 50%. This would be good for the diamond ring at C2 and C3 without a filter but you would wind up the exposure to get more corona. Depending on your field of view of course since really long exposures are only worth doing if you have a shorter focal length.
A huge advantage of digital over film is that you can see things in real time using live view so you can adjust exposures to suit the conditions. If this is your first eclipse though I would strongly suggest that you don’t spend too much time imaging but use binoculars and the naked eye to enjoy the view.3 August 2017 at 12:17 pm #578419
Thanks Grant. I will have the camera on a tripod un driven. The fov with the 400mm lens is sufficient that even if the eclipse moves off centre I will have plenty of room to capture the image. At totality I will bracket exposures down from 1/1000 and keep doing so for the allotted 2 mins or so of totality.
Tom.3 August 2017 at 12:20 pm #578420
Thanks for the information Nick.
I did watch the 1999 eclipse in France so this time I intend to get image it. I shall play around with live view and use it to adjust exposure accordingly.
Thank you for the advice.
Tom3 August 2017 at 12:52 pm #578421
Just played around with the video mode on my Canon 100D. Yes! This is the answer for totality. Allows me to adjust the exposure from the touch sensitive screen and look at the eclipse via the mark 1 eyeball.
So my routine will be to image the partial phase as a series of timed still shots in raw mode. Just before totality take off the filter and switch to switch to video mode at 1 minute before totality, adjusting exposure on the touch sensitive screen of the Canon. I will ensure that the video is at its highest setting and it is shooting in raw mode.
Hope this works out.
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