Siebert Star Splitter or Burgess/TMB Planetary

Hi Folks,

I am in the market for a 5-6mm planetary eyepiece, and am looking to spend $100 or there abouts. After some research I have decided to go with either the Burgess/TMB Planetary or a Siebert Optics orthoscopic Star Splitter. I will initially be using the eyepiece with an 8"F5 dob and in a few months with a 12"F5 dob.

I am drawn to the TMB, but I already own a 12.5 mm siebert standard eyepiece and am quite happy with it.
What do you guys reckon?
is there any other eyepiece I should be considering. Any advice would be greatly appreciated.

Trevor,
is this towards imaging, or just visual? You know yourself about the whole gretaer magnification is not always better thing. I have the clubs 12" Dob, and I rarely go past the 12.5mm eyepiece. I keep between that and the 25mm, sometimes using the barlow to try andmake out extra detail. I have a 6mm eyepiece (all these are 1.25" btw), but usually try and keep that for the star fields and clusters etc.

Seanie.

I agree, 200x is probably the limit of magnification that you'll get to use regularly. You'd get some use out of a 5-6mm eyepiece with the 8" but when you move up to a 12" f/5 the most you're ever likely to find use for is 8mm and even that won't be useful on many nights.

It might be a good idea to try using a Barlow with a 12mm or 12.5mm eyepiece instead of buying that 5-6mm eyepiece.

The real advantage of aperture isn't extra magnification, it's resolution. The limit of useful magnification in our atmospheric conditions is seldom better than 200x on a good night, though that's not to say that some like to push it more, even when it affects clarity. That's a personal choice. Really short focal length eyepieces are most useful on short focal length telescopes (like my Scopos 66 ED (FL=400mm) or Televue Ranger (FL=480mm), or even the N6AT I bought from Lidl (FL=762mm)).

Hi Guys,

I will purely be using the eyepiece for planetary and lunar work, so photography does not come into it.

At present I have two 6mm which I use on my 8" dob regularly but I am not happy with the image in either, one is a little soft and the other has ghosting issues.

I find that the 8" will take a 6mm on over half of the nights I want to use it.
On a 12" f5 the 6mm will give X250. This should not be pushing the 12" too much. Granted I wont be able to use it every night but I should get some use from it.

I reckon the TMB would be a safer bet. anyone have experience with these?

I have the 2.5mm TMB Planetary, which I use with my shortest FL scopes when conditions are suitable. It gives me 160x with my new Scopos 66 ED or 192x on the old Ranger. On the right night or on a clear day it's excellent, if atmospheric conditions are not right it has to stay in the box.

Apart from the 6mm I've seen nothing but good reports about the TMB Planetary eyepieces. Apparently there are 6mm eyepieces of the same name but an earlier design on the secondhand market (and possibly still sitting on dusty shelves in some shops) and those did have problems. The current 6mm gets the same kind of positive reports as the others.

Thanks for the heads up on the old 6mm