For suburbs.what mm eyepiece works best?

Looking to maximize my eyepieces to see the deeest dark sky objects possible through an 8" Hardon Dob...i noticed where i live i could see more with my 20mm 300 series plossl...fainter stars...than with my 30mm agena astro SUperview EP, big wide view but background is a bit lighter (i was looking closer to down...5:40am)...the 20mm has a 3 exit pupil...the 30mm a 5 exit pupil about...where i live i doubt it's of use to go higher than a 2 or 3 light pupil, due to all the light polution (ivan would know about this 1..lol), wouldnt u say? i live in coconut creek...near boca raton in south florida.

Any opinions would be greatly appreciated.
thanks!

Mike:

A few thoughts here...

- The optimal exit pupil depends upon the target, one really needs are range of eyepieces.

- For many smaller, fainter targets, I find a 2mm exit pupil is near optimal. The trade off when is between visibility and field of view. The widefield of view of a 32mm eyepiece makes locating the target easier but the higher magnification of makes it more visible.

- Widefield eyepieces cost more money, really good widefield eyepieces cost lots of money, many like the widefield view and it makes finding stuff easier.

- In my experience the one exception to this is the 9mm Synta 66 degree Widefield which is sold under a variety of names, Orion Expanse, Antares 8.6mm W70, plus a variety of others. This eyepiece has effective AFoV of 70.5 degrees (measured) and is reasonably sharp up to the edge even in an F/5 scope. These are available used for around $30.

- For some nebulas, deep sky filters are a real help.

jon

mike selz said:

Looking to maximize my eyepieces to see the deeest dark sky objects possible through an 8" Hardon Dob...i noticed where i live i could see more with my 20mm 300 series plossl...fainter stars...than with my 30mm agena astro SUperview EP, big wide view but background is a bit lighter (i was looking closer to down...5:40am)...the 20mm has a 3 exit pupil...the 30mm a 5 exit pupil about...where i live i doubt it's of use to go higher than a 2 or 3 light pupil, due to all the light polution (ivan would know about this 1..lol), wouldnt u say? i live in coconut creek...near boca raton in south florida.

Any opinions would be greatly appreciated.
thanks!

Yes, some what higher power works better than lowest power.
A powered finder scope can put one right on target, better than a finder eyepiece. Then observe the target with more magnification.
Most visual deep sky targets are small. Wide field is keano, but not a necessity. Plossl's are generally high throughput and do well if their eye relief (usually 75% of their focal length) is workable.

Also protect dark adaptation at the ep. With a drape over the head, or strategically placed screens (of any kind) around the scope, positioned to block intrusive lighting.

Mike,
I am not sure how much money you are wanting to spend. But I recently acquired the 24mm pan and it is truly an amazing ep. I share your frustration in that I live north of Atlanta, GA and there is no such thing as a dark sky outside of my house.

In general, increasing the magnification will have the effect of darkening the sky. So for example, my 24mm pan will yield about 15x more power, yet have the same true field of view as a 32mm Plossl. The 24 Pan shows the largest true field of view possible in an 1.25 focuser. Beyond that, it becomes a balancing act if you choose to give up field of view in exchange for better contrast.

There are less expensive versions of the 24mm pan. I recently sold my Meade 24.5, which is basically a "poor man's" Panoptic. I upgraded because with my f/6 telescope, stars showed noticeable distortion in the outer fifth of the field. In slower telescopes, there would be little difference between the two, and the 24 pan is about $200 more than the Meade. Just throwing my two sense in...