[jsmoraes (Jorge)]

An analyse of capture of an object with different time of exposition and ISO. They should contain the same data (amount of signal) although.

a) 120 seconds and ISO 800
b) 240 seconds and ISO 400
c) 480 seconds and ISO 200

All photos were conveted from RAW CR2 to JPG in Photoshop without any processing.

Diference of Histogram.


In animated GIF we can perceive:


1) less time exposition, more sharp the star.
2) less ISO, less noise
3) There isn't sifnificant color difference
4) There is loss of visual resolution when long time exposition.

Question:

The apparent loss of focus and shaprness with long time is due to:
a) RMS of guiding
b) capture of background glow (perhaps for humiditiy) around of star
c) capture of true data (signal) emited by star
d) contamination from excessive luminosity of adjascent pixels of sensor
e) others issues, inclusive those above ou some one of them.

The other animated GIF shows the difference having the 120 seconds 800 ISO as reference.


note: I will stack in DSS and compare the difference. I did a number of frames that will be the same total time of exposition for each one.