hi everyone i,m newish to astromny and have recently purchased a nexstar 102slt and am wondering what size lenses should i get as i have only the two a 25mm and 9mm i got with the scope . i.ve recently bought a 3x barlow ,well still waiting for to come in the post,and would like some advice as to what attachments ie. lenses and the like to get to improve my viewing .
3x barlow I recon will be an over kill on your scope...
Regarding lenses 9mm will be sufficient for planetary views and 25mm for deep space.it really depends what you are after.if it is deep space then get something low power with good FOV (they are really expensive tho) or if it is planets the higher mag like 12mm or 10mm.Another option and I think would be the best for novice is to get a zoom lens.Plenty of magnifications to play around and to understand how it works.
Hope that helps.
  