These are the important points to consider in SharpCap when attempting to capture a reasonable video of Jupiter:
· Set the Gain to 60 – 70%. (70% if using a Barlow).
· Start the Histogram ensure the Logarithmic checkbox is selected.
· Adjust the Exposure until the right-hand side of the histogram is at 80%.
The following need to be considered when trying to balance gain, exposure and frames per second (fps).
· Using a filter may require more gain (or longer exposures) to increase brightness levels.
· Using a Barlow will require more gain (or longer exposures) to increase brightness levels.
· Higher gain adds noise but this can be averaged out in stacking.
· Blurring caused by atmospheric seeing fluctuations cannot be cured hence a high frame rate is desirable to improve image quality.
· Exposures of less than 30ms have a chance to ‘freeze’ the seeing thus try to capture at 30 fps or better.
The calculation is:
fps = (1 second)/(exposure)
fps = (1000)/(exposure) [with units in milliseconds (ms)]
As an example, an exposure of 250ms would give:
1000/250 = 4 fps
As an example, an exposure of 30ms would give:
1000/30 = 33fps
All this will vary depending on factors such as atmospheric conditions, proximity of the moon and equipment. As a general guideline:
lower exposure => higher frame rate => better image
For this scenario, a large planetary disk, the shape of the histogram (with a logarithmic vertical scale) should be a ‘whale’. See http://docs.sharpcap.co.uk/2.9/#The%20Histogram for further information and background reading. In the picture below, SharpCap is shown ready to capture with the histogram undocked.