INSIDE PHOTOGRAPHY SEPTEMBER,2017

1) clear sky
2) remote control shutter release / intervalometer
3) tripod
4) camera
5) wild angle lens
d T h e L e n s
n
y R u d r a S h e k h a r D a s
B
We know that earth rotates on its own axis from west to east in every 24 hours. That means it rotates
360 degrees in 24 hours, which makes 15 degree rotation in one hour and in every 4 minutes
rotates one degree. I was able to get an exposure of 67 minutes and 30 seconds because after that
the sky was overcasted with clouds.
Now as per the previous calculation of the exposure I got the
trail of 16 degree, 52 minutes and 30 seconds. In this context I must mention to minimize noise
reduction I took a dark frame by attaching a lens cap.
Requirements to click a star trail:
Predetermination
Infinite focus : To get an infinite focus one has to fix the camera on the tripod and set the lens on
manual focus keeping the live view on. Then zoom in and when the stars appear as a dot you get an
infinite focus.
Exposure determination: While determining the exposure we have to keep in mind that the black
portion of the sky doesn't appears grey or else the faint appearing stars won't be visible.
Set up: I didn't had any tripod. I just took the camera and kept the lens towards the sky giving an
exposure of 30 seconds. I went on clicking photos one after the other and at last I took a dark frame,
since I knew that if the camera is on
for a long time it gets heated up and the level of noise
increases gradually. To reduce this noise
I took the dark frame.
Processing:
The processing of the photos was done by using a software named star track. I commanded the
software to add only the brightest points. Next the output was copied thrice, since for gap filling
minimum three photos are required. An object named threshold is present in gap filling which
enables the pixel size to either become small or big. As two photos have been merged it had a little
gap, which was filled in by increasing
the pixel size.