Better Barlow

[Mak the Night]

8 minutes ago, spaceboy said:

Sky watcher POS plastic x2 barlow 0.3/10

As high as 0.3? Surely you're being generous lol.

Apart from the Sky-Watcher POS, the only two Barlows I don't rate too highly, maybe a 5/10 maximum, are the Celestron Omni 2x and the bog-standard Celestron 2x from the Eyeopener Kit (first two on the left, top row).

[spaceboy]

0.3/10  just because it does something ......???

[johnfosteruk]

Based on my limited experience with nothing to compare to yet, I have to say you're being rather generous

[Mak the Night]

3 minutes ago, spaceboy said:

0.3/10  just because it does something ......???

It does something, I'm just not sure what though. Perhaps put off entire generations from using Barlows? lol

[John]

Cheap barlows were responsible for the poor reputation that the device acquired in the past I reckon. Get a good one and it's a very useful tool in the armoury of an astronomer. 

 

[RobertI]

Interesting reading, I have also been considering a barlow to use with my 8-24 Seben zoom and Megrez 72mm. Would a 2" barlow be of benefit or is it no use unless unless using 2" eyepieces? Sorry to OP for hijacking thread - hopefuly the answers will be useful too.

Rob

[johnfosteruk]

wouldn't there be a risk of vignetting?

[John]

A 2" barlow works fine with 1.25" eyepieces but a 1.25" barlow will do just as well in most circumstances.

The 8-24 zoom is not a very wide angle eyepiece so vignetting should not be an issue even with a 1.25" barlow. It can become an issue with eyepieces with very large field stops such as a 32mm plossl, 24mm 68 degree SWA etc, etc. With those you can loose a little light at the field edges with a 1.25" barlow.

 

[jetstream]

A Baader VIP is nice.

[Dave In Vermont]

If one is planning on buying ONE Barlow - ever - I'd suggest a 1.25" Barlow. Then if you decide to get a 2" - go ahead. As some telescopes out and about have a 1.25" focuser, you'd be set to use the 1.25" Barlow with it. You can fit a 1.25" into a 2" focuser. But not a 2" Barlow into a 1.25" focuser.

As for a 2" Barlow, I recently got a GSO 2," It, as I stated, is quite good. I was quite startled. And I also own TeleVue® Barlows, so I'm rather picky!

Bomb's Away -

Dave

[Louis D]

4 hours ago, RobertI said:

Interesting reading, I have also been considering a barlow to use with my 8-24 Seben zoom and Megrez 72mm. Would a 2" barlow be of benefit or is it no use unless unless using 2" eyepieces? Sorry to OP for hijacking thread - hopefuly the answers will be useful too.

Rob

I quite prefer using either my Japanese Orion Deluxe 2" 2X barlow with shorter focal length 1.25" eyepieces over my 1.25" TV 2X due to it greater sharpness.  I went back and forth many times to verify this.  Let me tell you, I was quite disappointed because the TV cost about $40 more in 1999 dollars.

More recently, I bought a GSO 2" 2X ED barlow.  It is nearly the equal of the Orion Deluxe when used bare with shorter focal length eyepieces.  I am hard pressed to see any significant difference.  However, add a TV Panoptic Barlow Interface, and it shines when used with wide field 2" eyepieces over 20mm.  There is literally no vignetting even with a 40mm Meade 5000 SWA or 30mm ES-82.  It actually sharpens up the outer field of the latter a fair amount.  The PBI doesn't interface well with the Orion Deluxe because it has too long of a focal length.  There's a weird vignetting/distortion going on at the edge.  However, the GSO ED's focal length is nearly identical to the TV Big Barlow, but it costs significantly less and seems to be nearly as good.

[Stu]

Some of the benefits of higher quality barlows can be in their ability to operate at higher multiples of magnification by extending the distance to the focal plane of the eyepiece.

If you can find a AP Barcon, they really are excellent, the best I've found and not stupidly highly priced. They will not degrade even up to x4 mag, although the extension tubes required can get a little unwieldy! I use one when binoviewing and can vary the magnification simply by adding  extensions using T2 quick changers, works very well and easier than changing two eyepieces each time. The Barlow element is 48mm and T2 threaded so very flexible too.

The Televue x2.5 PowerMate is also excellent, made better with a T2 Adaptor and Baader Click lock fitting on it.

The Baader VIP is of similar quality, although it will not take quite the same power as the Barcon. A very flexible system though which can be put to use in a number of different configurations.

I've also got a Zeiss Abbé Barlow which I use with the Leica Zoom for planetary work, very lightweight and lovely too but that one really is stupidly expensive so I wouldn't recommend it!

[John]

The AP Barcon is excellent. Interestingly the Antares 1.6x 2" barlow is reputed to use the same optics.

To add to the "premium" barlow picture, the TMB 1.8x barlow seems to have a shining reputation too. Out of production now though.

One might say now "meanwhile, back at the Revelation 2.5x at around £35 ....."

 

[johnfosteruk]

plenty to think about. Thanks everyone. 

2 hours ago, Stu said:

Some of the benefits of higher quality barlows can be in their ability to operate at higher multiples of magnification by extending the distance to the focal plane of the eyepiece.

If you can find a AP Barcon, they really are excellent, the best I've found and not stupidly highly priced. They will not degrade even up to x4 mag, although the extension tubes required can get a little unwieldy! I use one when binoviewing and can vary the magnification simply by adding  extensions using T2 quick changers, works very well and easier than changing two eyepieces each time. The Barlow element is 48mm and T2 threaded so very flexible too.

The Televue x2.5 PowerMate is also excellent, made better with a T2 Adaptor and Baader Click lock fitting on it.

The Baader VIP is of similar quality, although it will not take quite the same power as the Barcon. A very flexible system though which can be put to use in a number of different configurations.

I've also got a Zeiss Abbé Barlow which I use with the Leica Zoom for planetary work, very lightweight and lovely too but that one really is stupidly expensive so I wouldn't recommend it!

Stu. There's one thing that has consistently amazed me on SGL, more than the amazing images, more than the home obsys or DIY dobs and that's your inventory. Is there any gear you've not owned? ?

[Stu]

1 hour ago, johnfosteruk said:

plenty to think about. Thanks everyone. 

Stu. There's one thing that has consistently amazed me on SGL, more than the amazing images, more than the home obsys or DIY dobs and that's your inventory. Is there any gear you've not owned? ?

John, I won't comment as I would hate to take the thread further away from the £35 Revelation as John instructs.

EDIT Although as the OP perhaps you are better placed to say whether my post is of interest?

[Stu]

18 hours ago, johnfosteruk said:

 

This is why I love forums, no shortage of folks willing to help you spend your money, bending over backwards in fact.. 

Always happy to oblige.

I once asked the forum whether to sell my 21 or 17mm Ethos. I'm sure the basic answer was that I should keep both, and probably buy another one aswell. Most useful ??

[Mak the Night]

From what I can gather, many of the Revelation GSO Barlows are older stock and feature a draw tube safety undercut. Although they'll probably be replaced eventually with new stock. So, it could be worth bearing in mind if you have an aversion to undercuts.

[johnfosteruk]

7 minutes ago, Stu said:

John, I won't comment as I would hate to take the thread further away from the £35 Revelation as John instructs.

EDIT Although as the OP perhaps you are better placed to say whether my post is of interest?

Of course it's of interest, it's good to get a wide range of opinions and you're extremely qualified to comment. I don't mind if the thread digresses - it'll all help someone. 

[johnfosteruk]

2 minutes ago, Stu said:

Always happy to oblige.

I once asked the forum whether to sell my 21 or 17mm Ethos. I'm sure the basic answer was that I should keep both, and probably buy another one aswell. Most useful ??

Most obliging of the forum to be so helpful 

[Stu]

6 hours ago, John said:

The AP Barcon is excellent. Interestingly the Antares 1.6x 2" barlow is reputed to use the same optics.

To add to the "premium" barlow picture, the TMB 1.8x barlow seems to have a shining reputation too. Out of production now though.

One might say now "meanwhile, back at the Revelation 2.5x at around £35 ....."

 

The lens element in the AP Barcon can be removed and used in a very flexible way to achieve higher magnifications. I'm not sure if this is the case, I'm sure John will know.

I also understand that whilst the basic design might be the same in the Antares, the coatings and polish are of a higher quality on the Barcon which helps it achieve the x3 and x4 multiplying factors without image degradation.

[F15Rules]

Some great advice on here and from personal experience the 2" GSO Revelation unit is cracking value for money. I think the cost saving on these is more on the build than the optics..the barrel is quite thin compared to the heavy chromed brass of some better units, and this does mean it can "flex" a little when under heavy 2" eyepiece loading.

A lesser known barlow but in my view (I use one now) a superb barlow for the money, though not cheap, is the APM Coma Correcting 2.7x barlow. The name is a bit of a mouthful but is is a very versatile barlow:  http://www.apm-telescopes.de/en/optical-accessories/barlow-lenses/1-25-barlow-lenses/apm-comacorrected-1-1-4-ed-barlow-2-7-x.html?info=3742 .  It has brass compression anti-marring rings and other useful features as mentioned in the link.

The added advantage for reflector users such as yourself is that it will correct the coma that is inherent in this type of scope design, saving you from buying a separate unit for that purpose. It also works extremely well in refractors.

Mine was about £129 posted earlier in the year, and it is superbly built and the bottom lens component can be screwed into an eyepiece filter thread to give x1.5 magnification, whilst the full unit delivers x2.7 - this is great in my Vixen F7.7 apo refractor (F=795mm) as, for example, it gives the following choices in some of my eyepieces:

Eyepiece:               Native mag              x1.5 lens only                 x2.7 full unit

Pentax XL 5.2mm      x152                               x229                        x410 (used VERY rarely!)

Pentax XL 10.5mm    x75                                 x112                        x202

Morpheus 14mm       x57                                 x85                         x154

Pentax XW 20mm      x40                                x60                         x108

ES 68 24mm             x33                                 x50                        x90

 

I've been through a lot of barlows in my time and some of them were dire. The Celestron Ultima stands out as a good barlow which can be had used for under £50. If your budget is in that region I would go for one of those, or a new Revelation x2 1.25" version. If you can stretch a bit more, TV are good but I think the APM is better, for a little more cash. I guess the ultimate is the Powermate but they are not cheap at all, even used.

good luck with your selection.

Dave

[Stu]

4 minutes ago, F15Rules said:

Some great advice on here and from personal experience the 2" GSO Revelation unit is cracking value for money. I think the cost saving on these is more on the build than the optics..the barrel is quite thin compared to the heavy chromed brass of some better units, and this does mean it can "flex" a little when under heavy 2" eyepiece loading.

A lesser known barlow but in my view (I use one now) a superb barlow for the money, though not cheap, is the APM Coma Correcting 2.7x barlow. The name is a bit of a mouthful but is is a very versatile barlow:  http://www.apm-telescopes.de/en/optical-accessories/barlow-lenses/1-25-barlow-lenses/apm-comacorrected-1-1-4-ed-barlow-2-7-x.html?info=3742 .  It has brass compression anti-marring rings and other useful features as mentioned in the link.

The added advantage for reflector users such as yourself is that it will correct the coma that is inherent in this type of scope design, saving you from buying a separate unit for that purpose. It also works extremely well in refractors.

Mine was about £129 posted earlier in the year, and it is superbly built and the bottom lens component can be screwed into an eyepiece filter thread to give x1.5 magnification, whilst the full unit delivers x2.7 - this is great in my Vixen F7.7 apo refractor (F=795mm) as, for example, it gives the following choices in some of my eyepieces:

Eyepiece:               Native mag              x1.5 lens only                 x2.7 full unit

Pentax XL 5.2mm      x152                               x229                        x410 (used VERY rarely!)

Pentax XL 10.5mm    x75                                 x112                        x202

Morpheus 14mm       x57                                 x85                         x154

Pentax XW 20mm      x40                                x60                         x108

ES 68 24mm             x33                                 x50                        x90

 

I've been through a lot of barlows in my time and some of them were dire. The Celestron Ultima stands out as a good barlow which can be had used for under £50. If your budget is in that region I would go for one of those, or a new Revelation x2 1.25" version. If you can stretch a bit more, TV are good but I think the APM is better, for a little more cash. I guess the ultimate is the Powermate but they are not cheap at all, even used.

good luck with your selection.

Dave

That APM looks interesting Dave. It says it is meant for Netwonians to correct the coma in them, but you say it's excellent in you frac too?

One thing to add is that although Powermates are great, there are times when increasing the eye relief of an eyepiece can be beneficial - with short focal length Orthos for instance, barlowing a 9mm will give you a much more comfortable view than using a 5mm say.

[johnfosteruk]

The APM looks very interesting, a few reviews on CN giving it's coma correction abilities top marks. 365astronomy have them for the same £129 that you paid Dave. 

Things are becoming clear now, I have a shortlist.

APM - coma correction is a very nice to have and it's reasonably priced for the quality, won't become redundant with a refractor (which is inevitable at some stage) according to Dave (and the blurb on the manufacturer site)

Powermate - as near to optical perfection as you can get, nuff said

Revelation 2.5 - the budget option, best bang for buck, etc.

Now I just need to reorder my shopping list (new mount, decent cam for planetary, etc.) That's the most difficult decision, what to buy first from the list as funds become available.

 

thanks again all

[F15Rules]

56 minutes ago, Stu said:

That APM looks interesting Dave. It says it is meant for Netwonians to correct the coma in them, but you say it's excellent in you frac too?

One thing to add is that although Powermates are great, there are times when increasing the eye relief of an eyepiece can be beneficial - with short focal length Orthos for instance, barlowing a 9mm will give you a much more comfortable view than using a 5mm say.

That's very true Stu. I'm really looking forward to first light with my new Morpheus 14mm on the Moon with the APM barlow, it's a very comfortable eyepiece with a huge eyelens but I can get x154 with it using the barlow. I'm still waiting for first light at night, but daytime testing is very promising indeed and it is so much more comfortable for me to look through than the XW14 I sold to make way for this one.

Yes, it works great on both my Vixen 103mm apo and 80mm F15 achromat. Just one small "watch out"...on the ES 24mm 68 the helical tightening mechanism on the APM won't close tightly on this eyepiece. It is fine on all the others, just the ES is problematic - I think it's because the ES 24 has a tapered barrel and maybe it the thicker part of the barrel doesn't fit deep enough into the APM to be properly "grabbed" by the helical tightening mechanism? It would only be a real problem if you had a complete collection made up of ES eyepieces (and I haven't tried any other sizes so can't say if this applies to all their 1.25" products). The Pentax and Baader are absolutely fine with it.

Dave

[gunfighter48]

I had a GSO 2" 2X barlow and it was surprisingly good for the price. I wound up giving it to my adult grandson with a C102GT refractor and a bunch of eyepieces and stuff. I bought the ES 2X focal extenders both the 1.25" and 2" models. The 1.25"  fits my LS8 much better!!  I really like their focal extenders a lot.  Optically it was a better than the GSO but not tremendously better. They give me great views with no optical aberrations. Well worth the money to me.