Total Solar Eclipses have such a wide dynamic range from the dimmest phenomena of Earthshine, to the brilliant prominences of the chromosphere, that the best way to capture all this information is to take multiple images of increasing exposure known as brackets. However, since those brackets are dependent on a single "metered" setting, you need to know the full range of exposures beforehand to ensure that your bracketed sequence will cover the exposures required per the Solar Eclipse Exposure Calculator. At least for my Nikon cameras, the software does not specify anything more than the selected frames and EV interval. For this reason I created this bracketing calculator to estimate the exposures of 7 and 9 frame bracket sequences and I include tables that will calculate the estimated time it will take to perform them based on the equipment used and user preferences.

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The calculator is set up to automatically calculate based on the data entered in the white boxes. Start by updating the location, time in totality based on the location (refer to your location data or the Solar Eclipse Exposure Schedule). Then update the max FPS for your camera as this may affect the estimated shooting times. I have estimated that it will take me about 30 seconds to transition from my previous settings to bracketed exposures based on the process required for my camera, and then at least 5-10 seconds for the rig to settle after touching it. Test the time it takes you to make your own changes and update as required.

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In order to get all the exposures for all the eclipse phenomena, I will need to take two sets of brackets. This is not required, but since my camera limits larger bracket sets (7 and 9 frame) to only 1 EV increments or less, I don't have a better way presently. To determine the optimal 0 EV setting, I have modified the denominator of the shutter speed in the white box of step one and two so the -4 EV of Step 1 will cover the bright components such as the chromosphere, and +4 EV of Step 2 will properly expose Earthshine. Change these 0 EV values and/or the EV Incrament to fit your setup, and make sure to manually change your exposure settings to this 0 EV exposure when starting the bracket sequence during the eclipse.

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If you are using a 2 step process, you can also modify the time it takes to change settings and let the rig settle between bracket sets at the bottom of the Step 2 table. I have set up the modification time initially to 15 seconds, and rig settling time to 5 seconds.

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In the "Potential Bracketing Iterations..." table I have added an efficiency factor to normalize the max possible iterations with a number that is more achievable. Slight mistakes, the camera's buffer filling up and slowing write speeds, or anything else that inadvertently slows down your process could cost you valuable time that will throw off the whole process and cause you to miss frames. I have estimated roughly 10% inefficiency to help compensate for these types of unexpected delays, but modify this number as you see fit based on your own comfort.

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Lastly, there are multiple possible methods for interlacing the two steps of bracketing. I cover three options at the bottom of the calculator.

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If you find this calculator helpful for your eclipse preparation, please consider supporting my work by purchasing something from my Store​, or by donating to my Paypal account using the button below or @ShaunCTPhoto

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