Filling in those magnification gaps

[ixalon]

I'm thinking about picking up another Ethos (oh, yes, I've well and truly been bitten by the bug).

Since these things don't grow on trees, I'm trying to pick one which, when combined with Powermates and a reducer in various combinations would give me nice even gaps between magnifications without too much redundancy.

So... here's a little tool I quickly knocked up (basically visualising TV's calculator). If anyone would like other EPs/reducers/barlows added let me know and I'll add them...

Hope someone finds it useful!

Eyepiece / Reducer / Barlow Selector

[John]

Thats an interesting tool.

One of the good things about the Ethe (and the Naglers to a slightly lesser extent) is that you don't need so many of them because of their huge fields of view.

My 13mm Ethos replaced 13mm and 16mm Naglers and I've found I don't use the 20mm Nagler that much now either. The Ethos 13 in fact shows more sky than 25mm plossl would - both are 1.25" eyepieces of course.

Having been bitten by the same "bug" that you have I have added the 8mm and 6mm Ethe to my collection. I combine these with the excellent Antares 1.6x 2" barlow lens to give 5mm and 3.75mm focal lengths. Given that the last focal length is rarely used with my typical observing conditions I don't think I can justify the 3.7mm SX. A 21mm would be nice but the "bug" has not bitten so hard that I feel able to invest £700 in one yet !.

[ixalon]

Yep, that 21mm is so very tempting (typically has to be the most expensive - this money-saving idea of mine has somewhat backfired!) Combined with the 17mm, x2 and x4 powermates and f/6.3 reducer I already have it would give me pretty nicely spaced magnifications from x84 to x660 (max useful magnification of the C11 - one day I'll live somewhere with good enough seeing): 84, 104, 133, (165 & 168), 208, 267, (329 & 336), 415, 533 and 659.

If I went for the 13mm instead I'd have: 104, 136, 165, (208, 215), 271, 329, (415 & 431), 543, 659 and the rather useless 862. I'd rather have that extra on the wide end - but it's hard to justify those extra £££!

[John]

To be honest, I've found anything much over 300x to be pretty much unuseable in any of my scopes (and others I've used) under the observing conditions we usually get in the UK. My 6" refractor has a special corrector fitted which means that it can go to around 350x on a really good night, but that's the absolute limit I find.