Eyepiece recommendations!

[Nair al Saif]

Hello all,

I have recently been thinking about good eyepiece for planetary viewing. I have heard that the bst starguiders  are good. What eyepieces would work nicely in an 8inch f5.9 reflector 203/1200

 

There are some Skywatcher planetary eyepieces (most notably the 6mm and 7mm) with a FOV of 58degress?

Edited August 25, 2020 by Nair al Saif

[Louis D]

Both lines reportedly work well at ~f/6.  I can personally vouch for the 5mm and 8mm BST Starguiders.  They work very well at that f-ratio across the field.  Are they as good as my Delos, XWs, and Morpheus, not quite; but they're not far behind.  The biggest difference is the quality of the lens polish and stray light suppression which slightly reduces their contrast and ultimate resolving power.  However, for ~$60, they are hard to beat.

[Nair al Saif]

Ok, and the exit pupil is generous in the 8mm as well, I think on perfect nights I might Barlow it to get 340x magnification.. What about low magnification? Should I get the 18mm, I read somewhere that a 1mm exit pupil and an 3mm exit pupil ep is a must have?

 

on second thought I think a Barlow would be a better choice 2x (Lifehack you can get  1.5x by doing some weird vodoo magic)

Edited August 25, 2020 by Nair al Saif

[John]

Eyepieces between 30mm and 5mm in focal length will all be useful in your scope.

The BST Starguiders are good although there is some variation in quality across their focal lengths - the 25mm is probably the weakest although still a decent eyepiece.

Exit pupil is calculated as eyepiece focal length divided by the focal ratio of the scope. So all 8mm eyepieces will deliver the same exit pupil with your scope, as an example.

 

[Louis D]

4 hours ago, Nair al Saif said:

Ok, and the exit pupil is generous in the 8mm as well, I think on perfect nights I might Barlow it to get 340x magnification.. What about low magnification? Should I get the 18mm, I read somewhere that a 1mm exit pupil and an 3mm exit pupil ep is a must have?

Did you mean does the 8mm have generous eye relief?  If so, it has about 12mm of usable eye relief which is very comfortable when not wearing eyeglasses.

The 18mm is a decent performer compared to simpler designs such as Konigs, Erfles, Kellners, and low cost SWAs.  It isn't as good as the 5mm and 8mm BSTs, however; so temper your expectations.