Replacement Barlow.

[Charic]

Just sold my Revelation 2.5x Barlow, too powerful for Jupiter on my system on anything below 8mm?

Is there any benefit in buying two separate Barlow's  or just  a 2"  Barlow with the 1.25" adaptor.

I still feel the need  for a Barlow for extreme work on the Moon, but mainly  to Barlow my laser when tweaking the primary out in the field. I thought I'd get a way with the plastic Celestron 3XBarlow..........lol

The new Barlow will be 2x 

[rory]

The ultima is apparently a superb Barlow and one is for sale on the classifieds .

[Charic]

Cheers rory......seen that one, its  probably twice what I want to pay for at present, and I know, at the end of the day, you only get what you pay for, with regards to quality. The 2.5 I had was good. I think it was your recommend to me. But I only really used it on the Moon, as it was too powerfull for anything else planet wise, especially Jupiter, but now its gone, I cant Barlow my laser and dont have the 300x + power for the Moon when needed?

Edit. Having the Panaview brings an added dimension, so maybe get a 2"  2XBarlow with 1,25" adaptor. Still thinking about the Revelation version.  Just wandering if there is any reason not too? 

[John]

Barlowing long focal length eyepieces does not always work too well. As well as amplifying the power, a barlow pushes out the eye relief a fair amount and in the case of eyepieces that already have a fair amount, this can lead to the eye having to be held someway off the top of the eyepiece which lets light onto the eye lens causing unwanted reflections and loss of contrast.

The Celestron Ultima 2x is a very nice barlow as is it's clone, the Orion Shorty Plus. It's worth being aware that they are actually 2.2x though so you may find they deliver just a bit too much power. But if you can cope with 2.2x they are optically really nice.

The best 2x barlow I've used was the Tele Vue but we are in the Celestron Ultima price bracket, or higher even.

[Naemeth]

I personally prefer not to use barlows, and just to have a nice range of eyepieces to suit the conditions - I realise however that this is not a cheap option, however, so I'd suggest to get a barlow where the 2x element can be unscrewed (giving 1.5x when screwed into an eyepiece). I believe the Skywatcher premium barlow (~£30) does this.

HTH

[Charic]

Cheers John........and Naemeth......the  2x - 1.5X option sounds more like what I need, not to over-powering.  I think  I read somewhere  that  was an option for the  TAL 2x ?   I'll check out Barlows that unscrew. 

Any practical reasons for the full or shorty versions of Barlow?

[Naemeth]

Cheers John........and Naemeth......the  2x - 1.5X option sounds more like what I need, not to over-powering.  I think  I read somewhere  that  was an option for the  TAL 2x ?   I'll check out Barlows that unscrew. 

It is an option with the TAL, I've tried it myself .

[John]

The TAL 2x that I had used a conical section to mount the lens in. I didn't try actually unscrewing it from the barrel but it may have fitted into an eyepiece barrel - if Jonathan says it does, I'm sure it does ! 

Finding a TAL 2x barlow can be a bit of a challenge though as they are out of production now.

I happen to have a Skywatcher Deluxe barlow at the moment and tried it out a few nights ago out of curiosity (I don't usually use barlows either). It actually worked rather well in normal 2x mode and the lens element of that definitely can be used screwed directly into the bottom of an eyepiece to give 1.5x. The Skywatcher barlow seemed optically noticeably better than an Antares 2x (not an ED one) that I also had a couple of weeks back.

[Charic]

I just wish I'd kept my Revelation 2.5x until I tried another Barlow first. At least I'd still have a Barlow. A bit of an oversight on my behalf on this occasion.

[Naemeth]

It is a bit fiddly to do though, easy enough in the light but not so difficult with cold hands!

[Charic]

........Back to the benefits of the 2" adaptable Barlow. With the 1.25" adaptor in place, and the EP only using the centre section of the Barlow rather than the full 2" of glass, would there be any improvement or loss of optical quality?

 In the first instance, I was never going to Barlow a 32mm wide angle, but seems strange to completely omit that option if its available by having an adaptable 2" should the need arise. The Revelation 2" Adaptable is within my price range.

[John]

The Revelation 2" 2x ED barlow is good quality and great value for the price. It's heavier than a 1.25" barlow of course. The only other thing to note with it is to make sure you can insert it's long barrel into your focuser drawtube. Some drawtubes have a ring or baffle down inside a little way which would prevent the barlow from being fully inserted and that could affect how easy it is to get eyepieces to focus.

Using 1.25" eyepieces in a 2" barlow won't present any optical issues though, as long as the above point is not an issue for you.

Sorry nothing seems to be entirely simple ! 

[Charic]

To true John,  

So now, I'm hoping someone is using the Revelation  ED 2" adaptable version on their Skyliner. 

[Charic]

.........looks like I'm back with just a 1.25" Barlow. The list is getting bigger of possible candidates?

[Charic]

The TAL 2x that I had used a conical section to mount the lens in. I didn't try actually unscrewing it from the barrel but it may have fitted into an eyepiece barrel - if Jonathan says it does, I'm sure it does ! 

Finding a TAL 2x barlow can be a bit of a challenge though as they are out of production now.

I happen to have a Skywatcher Deluxe barlow at the moment and tried it out a few nights ago out of curiosity (I don't usually use barlows either). It actually worked rather well in normal 2x mode and the lens element of that definitely can be used screwed directly into the bottom of an eyepiece to give 1.5x. The Skywatcher barlow seemed optically noticeably better than an Antares 2x (not an ED one) that I also had a couple of weeks back.

Thanks John..........just secured one on ebay for £22 delivered. Was reading a reply on another thread,, that you'd left, about checking ebay, so took a peek on ebay and Bingo.   Also has a T-adaptor, so maybe my DSLR pics can be a little closer to the Moon / Jupiter

[John]

Thanks John..........just secured one on ebay for £22 delivered. Was reading a reply on another thread,, that you'd left, about checking ebay, so took a peek on ebay and Bingo.   Also has a T-adaptor, so maybe my DSLR pics can be a little closer to the Moon / Jupiter

Good buy ! 

I wasn't expecting that much from the Skywatcher barlow to be honest but it's much better than I was expecting. I've been testing some of the new Skywatcher SWA 70 degree eyepieces and used the Skywatcher barlow with the 13mm to create a 6mm and have had some lovely views of Jupiter with that combination  

[Charic]

I noticed FLO has the latest model with a milled safety undercut ,  £33 delivered. The one from ebay doesn't have the undercut, but primarily, I can Barlow my Laser in the field again,  and if and /when conditions arise, I can  still Barlow one of my primary oculars.

[John]

I noticed FLO has the latest model with a milled safety undercut ,  £33 delivered. The one from ebay doesn't have the undercut, but primarily, I can Barlow my Laser in the field again,  and if and /when conditions arise, I can  still Barlow one of my primary oculars.

A lot of folks don't like those undercuts as they can catch in the compression rings in the focuser tubes. 

[M4lcs67]

Sold my Ultima 2x barlow the other day (as it was becoming obsolete in my set-up due to it only being 1.25. The Luminos is 1.25 and 2") and was hardly ever used and took delivery of my new Luminos 2.5 barlow yesterday. A proper quality piece of kit. Just need to get out and try the thing out with different combinations of my eyepieces to see what works the best.

[Charic]

.......SW 2x D/Barlow arrived today, perfect condition visually!   Laser return (Barlowed) looks ok from the primary. Can't understand what the Celestron Barlow was doing, perhaps they use the bottom of a beer bottle as a lens? No adjustments required. Just need a clear night tonight to  catch Mars again before the Moon rises?

[rwilkey]

Cheers rory......seen that one, its  probably twice what I want to pay for at present, and I know, at the end of the day, you only get what you pay for, with regards to quality. The 2.5 I had was good. I think it was your recommend to me. But I only really used it on the Moon, as it was too powerfull for anything else planet wise, especially Jupiter, but now its gone, I cant Barlow my laser and dont have the 300x + power for the Moon when needed?

Edit. Having the Panaview brings an added dimension, so maybe get a 2"  2XBarlow with 1,25" adaptor. Still thinking about the Revelation version.  Just wandering if there is any reason not too? 

The PanaViews do not Barlow well, no point in Barlowing such a widefield ep anyway.

[Charic]

Cheers Robin........I`m certain I read that in a reply to someone else's thread, that you had replied to, so changed my mind on getting a 2" 

[Charic]

John / Naemeth.........You know what its like when you cant find some information, you just ask at the SGL.

Guys, you've both stated that If you remove the lens cell from the skywatcher deluxe Barlow and fit it directly to an eyepiece, it is reduced to a factor of only 1.5x  can that be measured or is that in black & white somewhere, because I cant find it?

Im printing a very small chart with some information on to adhere to the side of the scope, should anyone ask "what magnification is this telescope?" I just want to make sure that its exactly 1.5x.

I find it actually better with just the lens cell fitted, so my next question, is it possible to just buy just the lens cell anywhere. I could actually do with two?

[John]

I don't think it will exactly 1.5x because the exact amplification will depend on the distance from the eyepiece optics to the barlow lens element and that can vary if the barrel length varies. The further away from the eyepiece optics the barlow element is, the higher the amplification is. This is why, in eyepiece ranges which use a lens set in the barrel, the shorter focal length eyepieces are often longer / taller than the longer ones.

To work out the exact amplification you would need to know the focal length of the barlow lens element and the exact distance it will be positioned from the eyepiece optics. There is a formula that will then give the resulting amplification but I'm afraid that I don't know it  

[Charic]

Cheers John, many thanks.

So because the field lenses in my BST's are all different distances from the end of the tube that they sit in, the reverse would also be true, that its not exactly a 2x Barlow when used as a Barlow?

I love this hobby!