Asteroid occulation photograph ScopeX 2014
By Johan Smit, September 2014
The final image, Patientia, did not come easily.
The star that was occulted is very faint. There is always a problem with light pollution.
Test images showed that the best I could do was on a high ISO (6400) and a 4 second exposure.
That captured the faint target star reliably with manageable noise and light pollution.
A Canon 650D with 17-55 kit lens was used.
The lens was set to 35mm to cover a decent area to ensure that the event can be captured.
Aperture was set to F5.6, to get a good focus. The lens does not work well fully open.
A test image--named original is included. The area of interest is marked and the little star can just be seen.
The camera was mounted on my homemade camera tracker to follow the target area.
Then a sequence was taken from a minute or two before the event until I could hear my colleagues, who was timing the event visually, confirmed that it was over.
One 4 second image was taken every 5 seconds. Nearly a 100 images was taken.
Great was my happiness when I studied the sequence and found one image where the star was gone.
That image and the ones before and after were cropped and the light pollution removed to make the final collage.