To Gain or not to overGain
Posted: Tue Sep 11, 2018 5:29 pm
HI Robin, there has been so much talk with us guys and the AA183M/C hypercams about not getting enough stars to register in Pixinsight , and that has lead to hot discussions about the Gain values ... tool low ( 4) 400) not enough stars Ransac error in PIxinsight .
to hi a Gain 800~1250 (8-12) and now we are dealing with a big star burst. and a noise factor.
the thing is with the sensor analys which i like BTW, it would suggest Gain 350 offset 0... 68 sec subs on a 0.69 -e/Pix/sec
plug those # into SGP and your in big trouble, the ADU is about 78 out of 4098 and PI say " not gonna happen"...
after 6 mths of testing , we have had to get aggressive with Gain ( not so much with offset) to get any kind of image to stack.
then there the competition with there ASI1600MM Pro shooting Gain 200 ( above unity gain of 139) and 300~900 sec subs .with barely any noise
( I have the proof ) but who cares about that . LOL
SO the question is , what happens when we are shooting IC405 or IC1805 a faint target and we have to use the recommended Gain 400 or UNity
and also having to stay under 60 ~120 sec subs. the desired result do not match the expectations.
the other thing is Gain ( at unity ) 4/400 is fine if you want to shoot 300 subs per night and deal with the huge GIGAbyte ( 40-80)(bin1x1) total files in preprocessing. while the ASI1600MM boys only have to deal with 24-48 subs At 300 sec. in SHO.
SO again my Question is where is the happy medium ?
is it (Gain 350/offset 50 x 300 subs @ 60 sec) or (Gain 1250/offset 50 x 90 subs @ 45 sec)
So..low gain tons of subs or high gain fewer subs for the same dynamic range. or image brightness.
in simple terms LOw gain with 100s of subs.... or real high gain with very few subs. not with standing the offset ( blackpoint) always at 40 ish.
take all of this with a grain of salt, its just astro talk to find out why some do this and get great results and other try that and its left wanting.
According to NIck the ASI1600MM is a Panasonic chip and only is 56% QE as compared to our AA183M hypercam 86% @.
i suppose i need to push the Gaineven lower and try 4-8 minute subs and see if i can deal with the Starburst amp blow situation.
CHeers and keep up the great job via changes in SC 3.1 and beyond.
Astrodude / Mitch
https://www.youtube.com/watch?v=QgX9XDZlTfw&t=741s
to hi a Gain 800~1250 (8-12) and now we are dealing with a big star burst. and a noise factor.
the thing is with the sensor analys which i like BTW, it would suggest Gain 350 offset 0... 68 sec subs on a 0.69 -e/Pix/sec
plug those # into SGP and your in big trouble, the ADU is about 78 out of 4098 and PI say " not gonna happen"...
after 6 mths of testing , we have had to get aggressive with Gain ( not so much with offset) to get any kind of image to stack.
then there the competition with there ASI1600MM Pro shooting Gain 200 ( above unity gain of 139) and 300~900 sec subs .with barely any noise
( I have the proof ) but who cares about that . LOL
SO the question is , what happens when we are shooting IC405 or IC1805 a faint target and we have to use the recommended Gain 400 or UNity
and also having to stay under 60 ~120 sec subs. the desired result do not match the expectations.
the other thing is Gain ( at unity ) 4/400 is fine if you want to shoot 300 subs per night and deal with the huge GIGAbyte ( 40-80)(bin1x1) total files in preprocessing. while the ASI1600MM boys only have to deal with 24-48 subs At 300 sec. in SHO.
SO again my Question is where is the happy medium ?
is it (Gain 350/offset 50 x 300 subs @ 60 sec) or (Gain 1250/offset 50 x 90 subs @ 45 sec)
So..low gain tons of subs or high gain fewer subs for the same dynamic range. or image brightness.
in simple terms LOw gain with 100s of subs.... or real high gain with very few subs. not with standing the offset ( blackpoint) always at 40 ish.
take all of this with a grain of salt, its just astro talk to find out why some do this and get great results and other try that and its left wanting.
According to NIck the ASI1600MM is a Panasonic chip and only is 56% QE as compared to our AA183M hypercam 86% @.
i suppose i need to push the Gaineven lower and try 4-8 minute subs and see if i can deal with the Starburst amp blow situation.
CHeers and keep up the great job via changes in SC 3.1 and beyond.
Astrodude / Mitch
https://www.youtube.com/watch?v=QgX9XDZlTfw&t=741s