Barlows

[jay1]

Hi all,

I'm new to this forum and so i should introduce myself. I am from Scotland and have had an interest in astronomy for a long time. I will be picking up a Skywatcher 150p newtonian, fits my budget and it should be a good scope.

I've been reading through a lot of the posts and i am finding great information and advice but i have a question, namely;

Can you double up on Barlows i.e. 2, 2x to give a magnification of 4x ?

Thanks for any help.

[idbvideo]

Welcome to the forum. Simple answer is yes, its doable, just remember to tighten things down...

[umadog]

Yes, but there's probably no point if you're observing visually. You'll hit either the scope's magnification or the atmospheric seeing limit.

[jay1]

Hi,

Thanks guys, it's good to know that it is possible.

The reason i want to do it is that i want to use a webcam for a little photography and need a 4x, but they seem rare.

Also, does anyone know where i can get the Billetparts Lifecam adaptor? Don't want to pay £60 however.

Thanks

p.s. you guys reply fast to a newbie, kudos!

[Frank the Troll]

Why double up on barlows?

There are available x5 barlows, which are designed more for AP use.

[jay1]

Hi Frank,

I was thinking of utility. I'll get more use out of 2 barlows with low power e.g. 1-2x, 1-2.5x, than i will with 1 barlow at 5x. Of course cost is also a consideration.

However, a 5x may be worth looking at if the results will be better

Thanks

[umadog]

If I were betting, I'd say image quality would be better with a single 5x barlow than a barlow stack.

[Phaser6]

If you use a 2x barlow with say a 20mm EP this makes it the equivalent to a 10mm EP then if you add another 2x barlow it will be a 5mm EP equivalent with a lot of air and glass between the lenses so the image quality degrades quite considerably indeed. A 5x barlow to me is only any good for imaging purposes rather than viewing.

[jay1]

I thought too much glass would be the reason I couldn't double up. I may just have to pay out for a 5x.

Got my skywatcher 150p today but typically rain means I can't try it out.