Exposure times

[AstroVinny]

In practicing for the eclipse I have run into something that I do not understand.

I am using a Nikon D810 camera, a ZWO FF80 APO telescope F7.5 600mm focal length 80mm aperature, and an ND5 solar film filter from Spectrum Telescope.

When I use the Configuration Wizard to create a script, it is using an ISO of 100 and calculating an exposure of 1/1000 for the partial phases. I tested this on and the images of the full disc are VERY dark. So dark that you can barely see the image of the sun. I edited the images and I need 4 to 5 stops before the disk becomes a dark orange color (which I believe is properly exposed).

I can certainly edit the script to increase the ISO or the exposure time, or both. But my question is, how do I know that the calculations for the exposures during totality are going to be correct if the calculated exposures for the partial phases is not correct???

Any explanation of why these images seem so underexposed and what to do about totality would be GREATLY appreciated.

Tim.

[Rgalloway11]

Tim

ISO 100 @ 1/1000 def sounds too dark. I have been using a Celestron SCT 8 which has a focal length of ~2000mm, f10 and exposures approximately 1/100 to 1/250 and I am getting good results with the Thousand Oaks solar filters. Try utilizing this exposure calculator to adjust your script. http://xjubier.free.fr/en/site_pages/So ... osure.html
This calculator will give you good exposures for the partial phases as well as totality. Plug in the ISO and f-stop and it will give you the shutter speeds to use. Be sure to bracket exposures in the script.

Clear skies
Rick

[szigler511]

I've used a Baader ND 5.0 with an f/7.4 100 mm telescope. My exposures for partial phases have been 1/640 sec at ISO 100. Still, I'm planning to bracket +/- 1 stop on eclipse day. I have read that there is considerable variability in the ND values between different filter manufacturers, but I have only compared the Baader ND 5.0 to the Seymour Solar Glass filters. The exposures on the Baader ND 5.0 are stop or two brighter (sorry, I don't remember the exact value). During totality, I'm bracketing 14 stops, so I don't worry about exposure for totality. I talk about exposure in a talk I gave a while ago on the astroimaging channel. Here is a link if you want to check it out: https://www.youtube.com/watch?v=SpyrhhIckAg