Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Aug 14, 2017 3:45:12 GMT
A few months ago I picked up a second-hand 20cm f/5 Newt. It's not the AP version but it has plenty of in-focus - I can just squeeze in a 0.8x reducer. Took it for a cruise around on Saturday - first time out. Camera - GStar Ex3 Telescope - 200/1000 Mount - Heq5 Focal Reducer/Barlow - na Filters - na Exposure length - 25s Stacks - 0 Software - ToupSky Settings - Gain 0, Gamma 0.5, Histo 30-40 Any Processing - Auto Dark Subtraction Conditions - No moon, hazy but steady, ~ 30° alt, dark blue zone. General Location Esk, Australia -
|
|
elpajare
Member
Posts: 438
home town/country: Girona-Spain
time zone gmt +/-: 1
|
Post by elpajare on Aug 14, 2017 6:52:57 GMT
Good pick
Why do you put the gain to zero?
What advantages do you find?
|
|
|
Post by Dragon Man on Aug 14, 2017 9:42:54 GMT
Wow Robert, nice result! A single 25 second frame. Quite good detail for a single frame. Well done. The zero gain has helped with noise I usually prefer zero gain on all my stuff.
|
|
elpajare
Member
Posts: 438
home town/country: Girona-Spain
time zone gmt +/-: 1
|
Post by elpajare on Aug 14, 2017 15:55:53 GMT
I use always maximum gain with all my IMX224, stacking reduces noise and high gain reduces exposure time.
Im my opinion high gain can capture something more light from the stars and the object. Although the exposure is lower.
I have the same object at max gain ( with IMX244) and seems that are a little more stars. The same nebula seems with some more detail. But they are very small differences.
|
|
|
Post by Dragon Man on Aug 14, 2017 17:51:33 GMT
I use always maximum gain with all my IMX224, stacking reduces noise and high gain reduces exposure time. Im my opinion high gain can capture something more light from the stars and the object. Although the exposure is lower. I have the same object at max gain ( with IMX244) and seems that are a little more stars. The same nebula seems with some more detail. But they are very small differences. The difference is that not all of us stack. And low to no gain means that you can have a cleaner single frame for a quick view. Some objects do need stacking though if they are too faint. In those cases Gain can be raised a bit. Also I find that the darker the sky (no light pollution) the lower the gain can be.
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Aug 15, 2017 1:43:51 GMT
Thanks for the kind words.
I've only just started to try out 0 gain (ie gain set to 1 in ToupSky).
I've never had a fast enough scope to do it before. As Ken says, if you don't intend to stack then getting a clean image straight up is important.
Here's a quote from the camera manual "Gain - the Gain tab adjusts the sensitivity of the camera’s sensor. A standard 1.00 Gain is the camera’s default Gain, i.e., its normal sensitivity. Gain should be increased if object’s light is not sufficient and when longer exposure time is not available or desirable. Important: Increasing Gain introduces noise to the image."
I don't know anything about digital phtography so I refer back to the film days. We would always prefer a slower film (assume ASA = Gain) where possible to keep the grain small. ie try to achieve an acceptable result through exposure manipulation first.
|
|
elpajare
Member
Posts: 438
home town/country: Girona-Spain
time zone gmt +/-: 1
|
Post by elpajare on Aug 15, 2017 6:44:19 GMT
Thanks Ken and Robert.
Your answers have helped me to understand a little more how this type of photography works.
|
|