Sharpcap live stack

[Jonathancilia]

For 5 second exposures what gain and frames should i use for darks

[admin]

Hi,

the best gain to use depends on the model of camera you are using, which I don't think you've mentioned so far.

cheers,

Robin

[Jonathancilia]

ASI178MC i am using

[Jonathancilia]

whirlpool galaxy 1.png (498.58 KiB) Viewed 834 times

IMG_20230215_124119_001.jpg (98.68 KiB) Viewed 834 times

messier 3.png (737.7 KiB) Viewed 834 times

These are some images i am getting from sharpcap, what do you think? Sharpcap is amazing

[admin]

Hi,

for that camera I would be tempted to use a gain in the range of about 100 to 250 to begin with. If you look on the product page (https://astronomy-imaging-camera.com/pr ... 78mc-color), there is a graph of read noise changing with gain, and by 100 you have already taken advantage of the steepest part of the drop in read noise. By 250, it's pretty much reached the lowest value it will get to.

Nice images - the spiral galaxy has come out particularly well

cheers,

Robin

[Jonathancilia]

Thank you i will try that next time i go out. Your software is wonderful, i am having a great time watching all these DSO live in real time. Another question is can i use a canon eos 700D for live stacking? I heard that sharpcap wont support a dslr though

[admin]

Hi,

SharpCap does not support DSLRs directly. There is a free software project called 'ASCOM.DSLR' that might do the job of making your 700D work in SharpCap, but people's experiences with it have been mixed. Some people get it working nicely, others have no end of problems. There is a discussion on CloudyNights : https://www.cloudynights.com/topic/7076 ... ntax-sony/

cheers,

Robin

[Jonathancilia]

Is the ASI178MC a noisy camera? I am getting tons of noise when live stacking galaxies, maybe its because of my camera. I am applying darks and adjusting the gain and varying it and images still be noisy like this one. The histogram i keep the black and mid level close to each other otherwise the image will be very dim, but the noise will be far less when i move the mid level away from the black level.

sunflower galaxy.png (485.91 KiB) Viewed 734 times

[admin]

Hi,

it's not particularly noisy, but it is an older generation, so noisier than some of the more modern sensors.

One thing to be aware of is that the 178 sensor has very small pixels, which means that each one doesn't collect much light, so you may need longer total exposure (and longer sub frames) than you would with a larger pixel camera. This can be made even worse if you are using a high f-ratio telescope like an SCT.

Do check that you are using 16 bit mode on the camera (RAW16, not RAW8). Also it is odd that the image is totally monochrome in spite of the fact that it is a colour camera.

To give any more detailed advice, we'd need to know more details about your equipment and what camera settings you were using to take this image, along with how dark your skies are and how many frames went into the stack.

thanks,

Robin

[Jonathancilia]

I used raw 16 yes, my telescope is a skywatcher 6 inch virtuoso gti with focal ratio of 5. I use no reducer at all just the straight camera in the focuser.

Camera settings i used 5 second exposures with 350 gain but even with 10 second exposures and 350 gain bode galaxy was still noisy. This camera i know that its purpose is planetary and not dso