Screwing Barlows straight onto EPs

[CumbrianGadgey]

This is a thought that came to me when I saw that unscrewing certain Barlow elements and screwing these directly onto the filter holders of EPs gave a good image and reduced magnification. This could be a really useful feature when buying EPs on a budget because you could well get a whole raft of useful magnifications with two or three carefully selected EPs and one Barlow.

You may know that I'm also fiddling with a spreadsheet to advise on what EP sets to buy and I wanted a section to handle Barlow lenses, too.

The problem is, no Barlow Lens manufacturer seems to state whether their equipment can be used this way. Even if they can be screwed out and have the same thread, there's always the chance that the lenses fall out all over the floor in the process.

So the question is, how many of you have tried this and with what result? I know it can sometimes be done with a x2, giving 1.5 to 1.6x. Anyone tried it with other Barlows, X3, x1.5 etc?

[Damo636]

The barlow element on the Baader 2.25x can be unscrewed and fixed directly to the eyepiece for 1.3x. John reviewed it a little while back and I'm sure will chime in in due course.

[Reeny]

The problem is, no Barlow Lens manufacturer seems to state whether their equipment can be used this way. 

At least two manufacturers make a clear statement about the removable magnifier lens.

Skywatcher via FLO http://www.firstlightoptics.com/skywatcher-eyepieces/skywatcher-deluxe-2x-barlow.html

And Telescope house http://www.telescopehouse.com/acatalog/info-BL201.html

"The Revelation Astro 2x Barlow Lens comes with contrast-boosting blackened edging and an unscrewable, removable optical assembly, which can be screwed into a wide variety of eyepieces and accessories via a standard 1.25" filter thread. This alters the effective magnification of the barlow element, and is dependent on the spacing of optical surfaces. The ususal spacing in an average sized 1.25" eyepiece yields a magnification of around 1.5x when used in this fashion. This element removal can be very useful when attempting webcam imaging of the Moon and planets"

I have an unbranded Barlow similar to the skywatcher verison which needs to be used with the magnifier lens removed.

The 2x Barlow itself is rubbish, but the screw-in magnifier is tolerable at 1.5x

My proper Barlow is a 2.5x Revelation.

It won't come to bits because it has 3-elements which work properly.

Instead of using cheap Barlows, on cheap eyepieces - I would recommend getting a 2.5x Revelation 3-element barlow for £32, and some decent eyepieces.

http://www.telescopehouse.com/acatalog/Revelation_Astro_2_5x_Barlow_Lens.html

If you put rubbish gear in the scope, you will get rubbish results out.

I've tried it, been there, done that. 

[CumbrianGadgey]

The barlow element on the Baader 2.25x can be unscrewed and fixed directly to the eyepiece for 1.3x. John reviewed it a little while back and I'm sure will chime in in due course.

At least two manufacturers make a clear statement about the removable magnifier lens.

Skywatcher via FLO http://www.firstlightoptics.com/skywatcher-eyepieces/skywatcher-deluxe-2x-barlow.html

And Telescope house http://www.telescopehouse.com/acatalog/info-BL201.html

"The Revelation Astro 2x Barlow Lens comes with contrast-boosting blackened edging and an unscrewable, removable optical assembly, which can be screwed into a wide variety of eyepieces and accessories via a standard 1.25" filter thread. This alters the effective magnification of the barlow element, and is dependent on the spacing of optical surfaces. The ususal spacing in an average sized 1.25" eyepiece yields a magnification of around 1.5x when used in this fashion. This element removal can be very useful when attempting webcam imaging of the Moon and planets"

I have an unbranded Barlow similar to the skywatcher verison which needs to be used with the magnifier lens removed.

The 2x Barlow itself is rubbish, but the screw-in magnifier is tolerable at 1.5x

My proper Barlow is a 2.5x Revelation.

It won't come to bits because it has 3-elements which work properly.

Instead of using cheap Barlows, on cheap eyepieces - I would recommend getting a 2.5x Revelation 3-element barlow for £32, and some decent eyepieces.

http://www.telescopehouse.com/acatalog/Revelation_Astro_2_5x_Barlow_Lens.html

If you put rubbish gear in the scope, you will get rubbish results out.

I've tried it, been there, done that. 

Thanks for that people.

On a personal note, I'm undecided about Barlows but with the EPs I have (starguiders) I was a bit too conservative. A 2x Barlow also duplicates most of the range while giving me a tiny bit extra magnification using the 8mm and a stupid magnification that I'll probably rarely use with the 5mm EP. If that Revelation Astro is any good, the 1.5x feature is really useful and gives me the silly magnification (x400) if I'm feeling really optimistic or stood in Kielder Forest on a clear night! I'm a bit wary of using Barlows on my Skywatcher 130 because of the relatively flimsy focuser. Hanging all that lovely mass of Starguider an extra couple of inches out may not be a good thing, but its worth a try.

I'll do a search for John's review of the Baader.

In the meantime, I'll hope that more people step forward and tell me if they've used other Barlows like this and what they achieve.

Maybe the reason manufacturers aren't often keen to let us know it can be done (or deliberately make it impossible) is that they know we would not need to buy so many of their EPs if we could get a superb range with just one purchase and a couple of EPs...or am I being too cynical again?

If I get enough data, it could be worth incorporating into my spreadsheet but I have a feeling that this is not going to happen.