Bortle 2 and Bortle 8

[ZiHao]

How long should the total integration time in a Bortle 8 location be, in order to achieve the same image quality as in a Bortle 2 location. Let's say, I could recall I saw on Internet, that 1 hour in a dark site is equivalent to 10 hours of integration time in a light polluted area, is this true? I am asking this as my brother will be going to a very dark site, about 21.93 magnitude, Bortle 2 according to Clear Outside. Sadly I couldn't follow along as I still have to go to school  . Thanks in advance. Clear Skies!

[vlaiv]

That very much depends on several factors, one of them being the target brightness.

Other factors include, sampling rate, aperture, other noise sources and how they relate to LP noise (small or comparable).

I've run some calculations for my case, since I plan to move this autumn to darker location, and for my setup and some basic parameters (like target brightness about mag24-25) difference between mag 18.5 and mag 20.8 skies is about x6.

So in this particular case 1h of imaging in mag20.8 skies will achieve same SNR as 6h integration in mag18.5 skies.

Quoted figure of x10 is not far off, but actual value will depend on number of factors.

[Thalestris24]

2 hours ago, ZiHao said:

How long should the total integration time in a Bortle 8 location be, in order to achieve the same image quality as in a Bortle 2 location. Let's say, I could recall I saw on Internet, that 1 hour in a dark site is equivalent to 10 hours of integration time in a light polluted area, is this true? I am asking this as my brother will be going to a very dark site, about 21.93 magnitude, Bortle 2 according to Clear Outside. Sadly I couldn't follow along as I still have to go to school  . Thanks in advance. Clear Skies!

Hi

Samir Kharusi gives some numbers and examples

Louise

[Prolifics]

I am Bortle 5 here. Having light pollution filters help alot. Especially if in cities or urban areas.