Dobsonian size and light pollution

[jjz (Joe)]

Sorry for all the newbie questions, but can someone tell me what effect does inner city light pollution have on say a 12 inch Dob versus a 16" Dob?

Does the larger mirror compensate by being more sensitive, is it just drawing in more pollution and making things worse or is there no difference?


Thanks

Joe

[sn1987a (Barry)]

Bigger is better

[AG Hybrid (Adrian)]

Go bigger if you can afford it and physically handle it. A bigger scope will bring more of everything. LP and star light. Filters for nebula's negate most of the light pollution for those objects.

Also, target choice is important when observing from light polluted locations. Go for objects with high surface brightness. Star clusters, binaries, planets, compact globular clusters, planetary nebula's and other bright nebula's with a filter. There are a few bright galaxies as well. But, you wont pull in much detail over the galaxies central core.

[Satchmo]

The contrast ratio between the background sky brightness and the surface brightness of an extended object at any time for any given location is independent of the telescope and is not improved much by aperture. If the sky brightness is brighter than diffuse object - then no increase in aperture will help, but as a general rule the more aperture at your disposal the better . There are always objects that are more composed of resolvable stars that will look better in a larger scope even in a light pollutted sky as has been pointed out.

That being said a larger scope will really spread its wings given a good dark sky!

[AG Hybrid (Adrian)]

Originally Posted by Satchmo

The contrast ratio between the background sky brightness and the surface brightness of an extended object at any time for any given location is independent of the telescope and is not improved much by aperture. If the sky brightness is brighter than diffuse object - then no increase in aperture will help, but as a general rule the more aperture at your disposal the better . There are always objects that are more composed of resolvable stars that will look better in a larger scope even in a light pollutted sky as has been pointed out.

That being said a larger scope will really spread its wings given a good dark sky!

I laughed at your post Mark. I'm wondering how much of it a beginner would understand?

[jjz (Joe)]

Originally Posted by AG Hybrid

I laughed at your post Mark. I'm wondering how much of it a beginner would understand?

I had to read it a couple of times, but it makes sense.... I think.....

[Satchmo]

Originally Posted by AG Hybrid

I laughed at your post Mark. I'm wondering how much of it a beginner would understand?

Joe you are welcome to ask for clarification - you can't always dumb down concepts without risking losing the meaning that was being sought so a little effort to grapple with concepts is always productive

Put it another way - if the spiral arms of a galaxy or the surface of a nebula you want to look at a are fainter than the background brightness of your sky a larger telescope will not help ... If you are looking for faint stars that are brighter than the background sky but out of reach of a smaller telescope then a larger one will help .