Red channel - long exposures??

[AstroJay]

Hi,

Quick question regarding modified camera (canon 800D, filter removed, clear glass replaced) - Checking the histogram in APT it looks dangerously close to clipping the red channel on 180s exposures, iso 800. I’ve dropped down to 120s to move that channel back a little, pictures attached to show what I’m seeing. 

How do people manage the 3 min+ exposures with a modified camera and not clip the red channel? 

Target is the horse head nebulae.

Thanks

[wimvb]

I think you can safely lower the exposure to one minute, or iso to 400. There is basically no information to the left side of the histogram, so you are losing dynamic range. Otoh, if you overexpose the stars, you will end up with star cores that are difficult to repair. Try to find the exposure time that works best for you. Neve mind what others are using. Your gear + imaging conditions are unique for you. That's why it's important to experiment to find the best settings.