Barlow lens advice

[howson90]

Hi, my first post on this forum, this might be a common question you may have dealed with before but please bear with me! I am waiting for my telescope to arrive any day now, its a skywatcher evostar 90, i understand its not the most powerful but its all i could get within my budget and its rated as excellent value for money, im new to astronomy and it seems like a good telescope to wean me into whats what!

ive been looking into barlow lens, from what i gather its a lens that amplifies your existing magnification range, so is it as simple as say, with a 90 x eyepiece, if i add in a 2x 1.25" barlow lens it will double the practical magnification to 180x??

There must be some catches! I see that there is a range of prices on barlow lens, its seems to be on the how big it is? (if that what the inches symbol denotes!) what are the advantages of investing into a more expensive 1?

basically if anyone can give me some pointers as to what a barlow lens can offer to your telescope outfit and any advice on the best purchase that would be great. I really appriciate it.

Cheers!

Howson:icon_salut:

[oldfruit]

Hi and welcome to SGL. That should be a good starter scope.

A barlow lense increases magnification of eyepieces used with it. Like you have said, 2x doubles magnification, 3x triples magnification and so on. It is really that simple.

[John]

The "catch" if there is one is that it's adding more lenses (a barlow has at least 2) to the optical system so it pays to get a decent quality barlow lens rather than introduce a weak link to an otherwise decent scope / eyepiece combination. Decent quality barlows start at around £35.00 (the TAL ones).

[John]

The other "catch" is that the maximum useful magnification will still be limited by the seeing conditions and scope aperture (usually in that order !).

[Dave-Ryan]

Remember you can have too much magnification. With a Skywatcher Evostar 90 you will not want to go higher than 180 x magnification to get the best out of this telescope.

[starstalker]

another catch is the more u magnify something with a barlow the darker the image will be

[howson90]

thanks guys! i see your point about over-magnifying the telescope, ill keep that in mind to not order a barlow above 2 x. Are all barlow lens universally adaptable to all telescopes or would i have to purchase a lens from skywatcher?

[JamesM]

From what I've read there is certainly a difference between the cheaper ones and the very expensive ones such as Televue Powermates. These barlows lenses include corrective glass in addition to the magnifying element that effectively corrects unwanted effects created by magnifying the image through the eyepiece. There are many reviews written on the Cloudy Nights (USA forum) which provide high praise for this particular product and report that the mantra of "more glass means less light" is not the case with this particular make of barlow lens. As said above, this benefit of course comes at a price. If I was faced with only buying the cheaper models, I would prefer instead to stick to choosing appropriate eyepieces that provided me with the desired magnification rather than introducing additional cheap glass which would ultimately diminish the final image.

James

[John]

thanks guys! i see your point about over-magnifying the telescope, ill keep that in mind to not order a barlow above 2 x. Are all barlow lens universally adaptable to all telescopes or would i have to purchase a lens from skywatcher?

You can use any type that will fit your focusser - I think your scope has the 1.25" fitting. Personally I think the TAL ones are better quality optically than the Skywatcher ones.

[brantuk]

The Tal 2x barlow is a good balance of price and performance and the best vfm I've had in that price bracket. Get it here:

Tal

(FLO will try to price match if you find it cheaper)

[russ]

thanks guys! i see your point about over-magnifying the telescope, ill keep that in mind to not order a barlow above 2 x. Are all barlow lens universally adaptable to all telescopes or would i have to purchase a lens from skywatcher?

They are universally compatible, except, the shorty barlows are better suited to telescopes (refractors, SCT and Maks) that use a diagonal. So the Tal, Orion Shorty Plus and Celestron Ultima would be better suited to your scope than the Meade #140 Apo barlow for instance. This is so you don't stick the long barrel of a long barlow through the mirror in your diagonal.

[acey]

I would suggest that you try using your scope before rushing to buy extras. I got a barlow (a very good one) soon after buying my first scope, and I hardly use it, because of all the catches that others have explained. If I want to double the magnification then I get myself another eyepiece with half the focal length.

[russ]

I would suggest that you try using your scope before rushing to buy extras. I got a barlow (a very good one) soon after buying my first scope, and I hardly use it, because of all the catches that others have explained. If I want to double the magnification then I get myself another eyepiece with half the focal length.

A nice 6mm Planetary clone giving 150X would be a much better bet than barlowing the supplied 10mm.

[sengoksa]

It has to be tal all the way for price and perfomance they are

the best... But if u decide to spend more televue or the

celestron ultima you realy cant go wrong with either of them...

[Geno]

If your 10mm is anything like I got supplied with my scope it doesn't barlow well.

Don't get me wrong it isn't really bad and I have been using it for the last few months, and am still using it on planets/doubles until they let me have my BGO 6mm for xmas.

I did try it with the barlow for observing Jupiter and Saturn but was no good but I still get to see a fair amount of detail without the barlow.