Bino viewers

[Okeydokey]

As a concept... would it make any sense to spend my limited budget on bin viewer's that I could use on a Dobsonian in the garden, and then the same set of viewer's on some kind of scope significantly more transportable for when I go camping?

I got to this by trying to understand what 'deep sky viewing' is, then thinking that would be nice... but I do like the idea of seeing the planets i n 3D, and for some reason better views of the moon, something to do with my star sign I suspect (Cancer).

I will find out what and how a barlow does what it does, by the end of today.

[brantuk]

A barlow magnifies the object you're looking at (e.g. 2x, 3x, .....5x etc) depending on how it's designated. 2x is probably the most predominant type of barlow and the magnification most newbies go for. Effectively you can double your eyepiece collection overnight by getting a 2x barlow.

Be careful how you choose barlows though - over magnifying an object will make it go faint and grainy because you will also be magnifying the atmosphere that we all look through as well. I find 180x to 200x magnification more than enough for most sessions - but higher mag is possible with the right gear and more transparent skies. I also find higher objects magnify better than lower ones because the atmosphere is denser looking towards the horizon.

A 2x barlow effectively doubles your scope focal length (or can be thought of as halving your eyepiece size). For example a scope with 1m focal length and a 10mm eyepiece will give 100x magnification. Pop a 2x barlow in and it yields 200x mag.

Binoviewers are very impressive and work extremely well in Sct's and Mak's because you have a larger focusing range. But you have to have two identical eyepieces so it's more expensive. They can also be used in refractors but I never tried them on newtonian scopes. You need to be sure they come to focus in your scope.

Some BV's require a barlow to work properly and may or may not come with one included. It's a personal preference thing but some folks don't get on with BV's. Personally I find them awesome - star fields become totally immersive making it feel like you're right in the middle, planets look more rounded, and the moon feels like you're flying over the surface as if in a low plane. HTH

[Okeydokey]

That is really useful, thanks Brant. My Barlow knowledge is now up to speed, and curiously I now know what a Sct and Mak is, which is also entirley useful.

Your comments in respect of the BV's are very encouraging, just the kind of experience I am looking for tbh!

[brantuk]

You're welcome - but do try them first - find someone at a star party or astro soc with BV's - most folks will be happy to do that for you just to check you can get on with them.

Oh - I did look at the sun with them as well - it was phenomenal - but the rig was all TV, double stacked, and with 13mm Ethos eyepieces - very very expensive but totally unforgettable.

[Okeydokey]

Sorry for being a nuisance but when you say 'You need to be sure they come to focus in your scope' (I currently don't have a scope), what are the variables here?

[brantuk]

Well I'm not too good at the maths - but on some scopes you may need extra "back focus" or "forward focus" in order to make them work because some BV's may not focus within the range of a particular scope's focuser. That's why Mak's and Sct's are a reasonably safe bet cos they have a very wide range of focus positions.

The best thing to do is ask the retailer where you buy the scope if it will focus with binoviewers. They mostly know - but if not they will be able to try some out and confirm for you. Do ensure you use a proper astronomy retailer - high street stores are a bit useless.

It may be as easy as buying an extender or an appropriate barlow - but the retailer will know (or find out for you) cos they want to sell you a scope. I'd recommend FLO (SGL sponsors at top of the page) - they're excellent on advice and prices.

[Okeydokey]

That's great Brant thanks again. I have spent many hours looking through both twin and single optical devices having spent a few years in the Armed Forces and know the ergonomics well. I will endeavour to get behind the math and share what I find.