Light Gathering Power

[mert]

Anyone have a link for how well different sizes of mirrors perform? I had one once buy cant find it,

Many thanks

[Capricorn]

Basically (D1/D2)squared.

The calculator on your PC will do that.

If you want to know how much more an 8" will gather then a 6" then: D1=8, D2=6.

So 64/36 = 1.777. So an 8" gathers 77.77% more then a 6".

[mert]

Thanks, that is helpful

[umadog]

The rule of thumb is that for a "significant" difference in the views you'll want to at least double the area.

[Josh Wilson]

Here's a good one: Light Grasp. It's interesting to see how limiting visual mag, seems to stop gaining significantly as the aperture gets larger. Anyway, hope you like it.

[Peter Drew]

It's just the numbers that stop gaining as fast, not the light grasp. Brightness (magnitude) is not linear unfotunately, if it was then if a 6" could see mag 12 then a 12" would see mag 48.

[E621Keith]

It's just the numbers that stop gaining as fast, not the light grasp. Brightness (magnitude) is not linear unfotunately, if it was then if a 6" could see mag 12 then a 12" would see mag 48.

but magnitude scale is not linear either, it's logarithmic. The brightness of each magnitude is differs by 2.5 times. So a 12" scope (4x light gather) will go less than 2 magnitude deeper than a 6".

edit: sorry miss read you post, I totally agree.