lostpleiad

lostpleiad.........I find that if my eyes are averted from the light pollution, then the image from the telescope appears to look better, this is just by having the eyes dark adapted. I have a snood made from camping  underlay foam, but often just forget to apply it to the scope.  My telescope is looking through the light pollution, rather than directly at it, but my eyes are  getting the full glow when looking around the garden, but there are dark areas where I can sit, and my eyes are shielded to some degree, from direct light sources. The best results from my garden is when in/using my my Dob-Tent?

A dark bath towel over my head also helped to keep  some of the light at bay, and reduces the cold around the face, before the tent arrived.

Seriously expensive eyepieces are better corrected off-axis(no edge distortion of the image) and suitable/better for faster focal ratio telescopes and may have wider views, but they wont rid your light pollution. As Moonshane points out, could you tell if there was much difference?

I used to visit nearby Clanfield? I thought it had dark skies, but with so many new dwellings there now (since my Days) that I would assume it has more skyglow now?

I have a big piece of material I wrap around my neck like  a Bedouin, and pull over my head when viewing. I find it helps to cut out light distraction and prevent me straining one eye closed! But I like the idea of a dob-tent. I couldn't find anyone selling them anymore....I' wondering if I should make my own, because there a re a lot of insecurity lights around me where I am

Hi, I'm in the process of learning about this myself, but the contrast is the difference between the objects you are observing. In this case it will be the contrast between the stellar objects and the background of sky. Increasing magnification results in less surface brightness which can effectively reduce the ambient glow of a background sky. As stars are pins of light they have a low surface area and high surface brightness and consequently do not dim as much as an object that is larger like the sky or a huge nebula.

As I understand it, it's getting the balance if magnification right for a particular object to give good contrast but not reduce it's brightness too much.

Regarding the original question, I'd say good EPs will be worth it in any case but understanding the science and math involved can help you make informed decisions about what EPs to buy. I found this site super useful:

http://www.rocketmime.com/astronomy/Telescope/telescope_eqn.html

Great link - thanks!

@BigMakStutov - thanks for your explanation. What I didn't understand is the effect of exit pupil. I thought that the difference between a 5mm exit pupil and a 2mm exit pupil would just be that for a dark adapted pupil, a lot of the 5mm exit pupil would be wasted. But you are talking about it as if it increases the contrast to have less exit pupil - why is that?

Thank you to everyone who has replied on this thread. There's more information here than in most books on astronomy! Particularly thanks for the useful links and explanations - I'm still working my way through them. Unfortunately, it looks like I might be spending some money after all but at least I know what I am looking for....

Thanks for all the replies.

I don't understand about increasing the contrast - does increasing magnification increase contrast? Sorry for the stupid question..

I'm confused about whether to stick with what I've got, or invest in an 18mm EP - I was veering towards the X-Cel after reading a comparison with BST on here. I also had my eye on a 31mm Baader Aspheric - would that be worth getting? It's 82degs I think...

I'm starting to wonder if I should invest in some better eyepieces, but is it worth it, when I have light polluted skies?

I have a an 8inch Orion XT8 dobsonian. My eyepieces are what I could afford after shelling out on the scope.

• Seben 8-24mm zoom 
• 6mm 58 Degree BST Wide Angle Eyepiece
• Series 500 1.25" 40mm Plossl Eyepiece
• 28mm Orion 2inch eyepiece (came with scope)

These days I use the Seben or the 28mm exclusively. The 6mm and 40mm stay in their case all of the time (the first is too dim on anything except the moon, and the 40mm doesn't seem to do anything useful (I bought it hoping for nice wide views, but the 28mm is better for that).

I live in Banbury, near to the town centre with a reasonable amount of sky glow and neighbour's security lights. However, with the Seben I have seen plenty of nice objects - globular clusters, a few planetary nebulae, including some of the smaller ones like the blue snowball,  several galaxies like Bode's nebula, the Leo triplet, what I think was the Whirlpool once. I've never managed to see M1, or the Triangulum galaxy - pretty sure the computer on my scope has me looking right at it!

Hopefully that gives an idea of what I can 'get at' from my location and conditions.

So my question is - would I benefit from investing in, say, a Baader Hyperion zoom, or some Hyperion 68deg eyepieces, or the Celestron Xcel LXs? I mean - would I see more? Or better? Or would my location limit me from seeing anything more than I already can? 

Many thanks..