Tej Dyal
M13 Great Hercules Cluster via 80mm refractor from London living room window on Alt Az mount - Improved
Yesterday, I uploaded an image of the M13 which I felt rather chuffed with considering its taken in London on an Alt-az mount at my living room window. So I proudly showed my mentor, Rupert. (see my previous one in my gallery for comparison) .
Then he tells me, I can do better with the data I have. Throw away all of the ISO 3200s and ISO 6400s and just stack the ISO 1600s...then do my usual post processing. And bloody hell, sure enough, I get a hell of a lot more detail and colours from just using the ISO 1600 frames (420 X 4sec exposures). This is because the higher ISOs' higher noise levels serve as a bottleneck to extracting all the information possible. lower ISOs retain a wider dynamic range of colour information and less noise. Now I knew this about ISOs but I thought combining all the data from all ISOs with separate master dark frames for each ISO would give me even more data. But nope, my mentor, Rupert was right (as he always is), its the opposite.
So yesterday, I set about showing that we can do deep space astrophotography from inside the house at a bedroom or living room window in inner London but today, I humbly present a better example.
My original writeup on this restricted capture imaging project and my thoughts on The Great Hercules Cluster M13 is on my previous image.
Info:
Light Pollution Bortle grade (1 darkest sky, 9 highest light pollution) : 8-9
Telescope: 80mm Equinox APO refractor with a field flattener
Mount: Nexstar 6/8SE Alt Az on a sturdy table but on rickety floor boards!
Camera: Canon 650D unmodded
No light pollution filters
420 X 4 Sec Light frames
ISO 1600
50 Dark frames
Stacked with DSS (Deep Sky Stacker). Manually adjusted RGB levels.
Used curves and levels repeatedly with saturation in Photoshop and Camera Raw.
M13 Great Hercules Cluster via 80mm refractor from London living room window on Alt Az mount - Improved
Yesterday, I uploaded an image of the M13 which I felt rather chuffed with considering its taken in London on an Alt-az mount at my living room window. So I proudly showed my mentor, Rupert. (see my previous one in my gallery for comparison) .
Then he tells me, I can do better with the data I have. Throw away all of the ISO 3200s and ISO 6400s and just stack the ISO 1600s...then do my usual post processing. And bloody hell, sure enough, I get a hell of a lot more detail and colours from just using the ISO 1600 frames (420 X 4sec exposures). This is because the higher ISOs' higher noise levels serve as a bottleneck to extracting all the information possible. lower ISOs retain a wider dynamic range of colour information and less noise. Now I knew this about ISOs but I thought combining all the data from all ISOs with separate master dark frames for each ISO would give me even more data. But nope, my mentor, Rupert was right (as he always is), its the opposite.
So yesterday, I set about showing that we can do deep space astrophotography from inside the house at a bedroom or living room window in inner London but today, I humbly present a better example.
My original writeup on this restricted capture imaging project and my thoughts on The Great Hercules Cluster M13 is on my previous image.
Info:
Light Pollution Bortle grade (1 darkest sky, 9 highest light pollution) : 8-9
Telescope: 80mm Equinox APO refractor with a field flattener
Mount: Nexstar 6/8SE Alt Az on a sturdy table but on rickety floor boards!
Camera: Canon 650D unmodded
No light pollution filters
420 X 4 Sec Light frames
ISO 1600
50 Dark frames
Stacked with DSS (Deep Sky Stacker). Manually adjusted RGB levels.
Used curves and levels repeatedly with saturation in Photoshop and Camera Raw.