Filters & Stuff

[Crackers (Craig)]

Before I start with the dumb questions, a big thanks must go to everyone who helped me to choose a scope (SW 10"dob) and associated bits and pieces, great advice and I'm having a ball discovering the heavens. Particular thanks to Eric, Rob, Steve and Brendan. I've been out every night since it arrived and every night I find something new and amazing.

Tonight is cloudy and with the happy coincidence of being sober, it's time to ask a handful of questions that have popped up over the last week.

1. Barlow lenses. 2x seems to be the most recommended, but are 3x worth considering. Being a bloke, I'm biologically programmed to thing bigger is better, but I'm assuming that there is a trade off somewhere.

2. Are 2" eyepieces worth the extra expense?

3. While I was looking at the Orion neb, I noticed it was green-blue (much different to all of the photos that I have seen). I thought that I had read somewhere that most visual observation would be b&w, but obviously not. Would filters help give the actual colouration of DSO's? Reds are visible in stars, so why not in DSOs?

One final point, whoever invented the Telrad should be awarded the highest honour afforded by amateur astronomers - it's brilliant

Cheers,

Craig

[mark3d]

we have seen the green colour in orion nebula in a 10" dob too! just a hint of colour though.. i understand you need to go up in aperture to start getting more. i think people say 'no colour' to prepare people who might otherwise be expecting magazine photo style colour

my guess at why stars have colour but generally not other objects is that the stars are brighter? more photons to make the cones in your eyeballs work?

the factor of the barlow depends on your eyepiece selection... as the magnification gets higher, the ability to use it depends more on the conditions. so your 21mm eyepiece, with a 3x barlow acts like a 7mm... but a 2x makes it 10.5mm - that might make the difference between usable and not, depending on the seeing any particular night. plan your eyepieces carefully to get the best value from your $ i dont think there is a technical reason not to get a 3x.


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