Jump to content


Photo

What size barlow or Powermate do you use

  • Please log in to reply
37 replies to this topic

#1 Lance1234

Lance1234

    Ranger 4

  • *****
  • Posts: 374
  • Joined: 01 Nov 2012
  • Loc: SoCal

Posted 21 January 2013 - 09:09 PM

Curious what size Powermates or barlows people use (1.25" or 2" or both); and if you use a 2", why? For purposes of this discussion I'm using the term barlow to refer to the whole class of Powermates, telecentric barlows, regular barlows, etc. Obviously a 2" barlow allows you to barlow 2" eyepieces, but why would you want to?

The benefit of a barlow, it seems to me, is that it enables you to get high magnification while using eyepieces with reasonable eye relief and good size eye lenses, rather than having to stuff your eye into a pinhole. Given that 2" eyepieces are only required when focal lengths get longer than the mid teens to twenty something mm, and then only for wide angle eyepieces, you can still get good eye relief & lens sizes in focal lengths that don't require a 2" eyepiece, i.e 16mm Nagler, 20mm XW, etc. So I would be interested in the benefit people see in using 2" barlows.

#2 GeneT

GeneT

    Ely Kid

  • *****
  • Posts: 12790
  • Joined: 07 Nov 2008
  • Loc: South Texas

Posted 21 January 2013 - 09:57 PM

I have a 2" focusser and therefore use a 2" Powermate. If I used a 1.25 inch Powermate, I would have to us an adapter. I do have use an adapter for my 1.25 eyepieces, but I have outfitted all my 2" eyepieces with adapters. A 2" Powermate will also handle my 2" eyepieces.

#3 John Kuraoka

John Kuraoka

    Ranger 4

  • *****
  • Posts: 371
  • Joined: 12 Dec 2012
  • Loc: Sunny San Diego, CA

Posted 21 January 2013 - 10:12 PM

I have a 1.25" focuser and diagonal, so I use a 1.25" 2x Barlow.

#4 rathbaster

rathbaster

    Viking 1

  • *****
  • Posts: 925
  • Joined: 21 Mar 2008
  • Loc: East Bridgewater, MA

Posted 22 January 2013 - 12:31 AM

My primary scope can only use 1.25" eyepieces, so I use a 1.25" Powermate.

-Joe

#5 beatlejuice

beatlejuice

    Surveyor 1

  • *****
  • Posts: 1638
  • Joined: 05 Apr 2011
  • Loc: Hamilton, ON,Canada

Posted 22 January 2013 - 01:34 AM

I have 2 inch focusers but I use a 1.25 inch powermate because I don't have any 2 inch eyepieces that I want to power up. The TV 2.5 is great.

Eric

#6 ibase

ibase

    Aurora

  • *****
  • Posts: 4582
  • Joined: 20 Mar 2008
  • Loc: Manila, Philippines 121°E 14°N

Posted 22 January 2013 - 02:03 AM

Same here, 1.25" Powermate 2.5x.

Posted Image
TV 1.25" Powermate 2.5x, TV 2,3x

Best,

#7 johnnyha

johnnyha

    Fly Me to the Moon

  • *****
  • Posts: 6500
  • Joined: 12 Nov 2006
  • Loc: Sherman Oaks, CA

Posted 22 January 2013 - 03:35 AM

The 2" 2X Powermate with the body removed and a T-ring adapter installed, is imho the finest binoviewer barlow on the market. Gives superior images at high power and works in refractor, SCT or newt with no backfocus issues.

And unlike a regular 2X barlow, the telescentric Powermate stays at native 2X with the binoviewers (a regular 2X barlow is more like 3X-4X through binoviewers).

Now for regular eyepieces, I agree with the OP that it's silly to barlow 2" eyepieces. Love my 1.25" 2.5X Powermate!

Attached Files



#8 Damo636

Damo636

    Ranger 4

  • -----
  • Posts: 326
  • Joined: 16 Aug 2011
  • Loc: Co Fermanagh, Northern Ireland

Posted 22 January 2013 - 07:31 AM

Had a 2" Powermate but now use a 2" 1.6x Antares.

#9 MrFancypants

MrFancypants

    Sputnik

  • -----
  • Posts: 26
  • Joined: 05 Jul 2012
  • Loc: Swift Current, SK

Posted 22 January 2013 - 07:35 AM

I bought a 2" for my 14mm ES 100 degree.

#10 David Knisely

David Knisely

    Hubble

  • *****
  • Posts: 15635
  • Joined: 19 Apr 2004
  • Loc: southeastern Nebraska

Posted 22 January 2013 - 08:18 AM

Johnnyha wrote:

Now for regular eyepieces, I agree with the OP that it's silly to barlow 2" eyepieces. Love my 1.25" 2.5X Powermate!


Well, it isn't really silly to Barlow a 2" eyepiece. One of my favorite combinations for globulars is my friend's 20mm Nagler and his 2x Powermate. In my Dob, it gives a nice wide field with just the right magnification (188x) to really start to "get into" the object without the field of view getting a little too restricted. There is also another reason to use a true Barlow: eye relief. If I use my 36mm Hyperion Aspheric with my friend's 2" barrel 1.5x Siebert Barlow, the eye relief gets extended enough that I can view pretty much the entire field of view with my glasses on. Clear skies to you.

#11 dpwoos

dpwoos

    Surveyor 1

  • *****
  • Posts: 1521
  • Joined: 18 Oct 2006
  • Loc: United States

Posted 22 January 2013 - 08:59 AM

The benefit of a barlow, it seems to me, is that it enables you to get high magnification while using eyepieces with reasonable eye relief and good size eye lenses, rather than having to stuff your eye into a pinhole.


You cite one benefit of a barlow, but certainly not the only one. Many folks use a barlow to get more magnification from an eyepiece because they don't have another eyepiece that will do the same job as well. In fact, it may be that in their estimation there doesn't exist another eyepiece that will do the same job as well.

#12 Aquarist

Aquarist

    Apollo

  • -----
  • Posts: 1041
  • Joined: 27 Aug 2012
  • Loc: Illinois

Posted 22 January 2013 - 09:07 AM

2" Powermate

#13 csrlice12

csrlice12

    Voyager 1

  • *****
  • Posts: 11245
  • Joined: 22 May 2012
  • Loc: Denver, CO

Posted 22 January 2013 - 09:16 AM

Uh, none. I have a 1.25" 2X barlow--it sets in my case to soak up all the dew so the eyepieces don't get wet...Didn't intend for this to happen, bought the barlow fully intending to use it--and I did, initially, but after a time and obtaining additional f/l eyepieces, it now jus sets there. But, I'll keep it, you never know.....and everyone should have one barlow.

#14 Lance1234

Lance1234

    Ranger 4

  • *****
  • Posts: 374
  • Joined: 01 Nov 2012
  • Loc: SoCal

Posted 22 January 2013 - 10:24 AM

One of my favorite combinations for globulars is my friend's 20mm Nagler and his 2x Powermate.


David,

Why just not use an 11mm Nagler or is it just the flexibility to double any EP?

#15 russell23

russell23

    Skylab

  • *****
  • Posts: 4458
  • Joined: 31 May 2009
  • Loc: Upstate NY

Posted 22 January 2013 - 12:55 PM

I have 1.25" and 2" barlows/powermates. I don't have a problem with barlowing my 2" 28mm ES68. In fact, if I wanted to spend the money, I could probably be perfectly happy with the 28mm ES68 and a couple of 2" Siebert barlows.

Dave

#16 Starman81

Starman81

    Vanguard

  • *****
  • Moderators
  • Posts: 2055
  • Joined: 06 Mar 2008
  • Loc: Metro Detroit, MI, USA

Posted 22 January 2013 - 02:12 PM

In 1.25": TV 2x barlow, Orion Shorty 2x, TV Powermate 2.5x
In 2": GSO 2x ED barlow

Also, add me to the number of folks that don't mind barlowing 2" eyepieces. I barlow the 13 Ethos and ES100 9mm with great results and also the 22T4.

#17 David Knisely

David Knisely

    Hubble

  • *****
  • Posts: 15635
  • Joined: 19 Apr 2004
  • Loc: southeastern Nebraska

Posted 22 January 2013 - 02:58 PM

One of my favorite combinations for globulars is my friend's 20mm Nagler and his 2x Powermate.


David,

Why just not use an 11mm Nagler or is it just the flexibility to double any EP?


It is the flexibility. I would have gone with the 11mm or 9mm Nagler except that I don't have either eyepiece. I have a 8.5-12mm Speers Waler that I can set to 10mm, but the view just isn't quite the same as the Nagler-Powermate combination. Indeed, using a Barlow instead of the Powermate will increase the eye relief as I mentioned, which in some cases for those of us who wear glasses can be a real boon to observing. For less complex eyepiece designs, going to the longer focal lengths provided by Barlows/Powermates can help their off-axis performance as well (mostly in somewhat reduced off-axis astigmatism). Clear skies to you.

#18 MRNUTTY

MRNUTTY

    Surveyor 1

  • *****
  • Posts: 1862
  • Joined: 22 Nov 2011
  • Loc: Mendon, MA

Posted 22 January 2013 - 05:03 PM

I have a 2x, 4x 2" Powermates for a slew of 2 inch TV's and ES100's. As long I can heft it, and it doesn't break anything, why not?

#19 Scanning4Comets

Scanning4Comets

    Markus

  • *****
  • Posts: 13776
  • Joined: 26 Dec 2004
  • Loc: Canada

Posted 22 January 2013 - 05:57 PM

I have 1.25" and 2" barlows/powermates. I don't have a problem with barlowing my 2" 28mm ES68. In fact, if I wanted to spend the money, I could probably be perfectly happy with the 28mm ES68 and a couple of 2" Siebert barlows.

Dave


Dave, does the ES 28mm vignette in a barlow? I know my 28mm and 20mm Series 5000 did, but the 20mm ES 68 didn't. I'm now wondering if the Meade series 5000 68's and ES 68's are a bit different in lens design? Hmmmmm.

Cheers,

#20 russell23

russell23

    Skylab

  • *****
  • Posts: 4458
  • Joined: 31 May 2009
  • Loc: Upstate NY

Posted 22 January 2013 - 06:41 PM

I have 1.25" and 2" barlows/powermates. I don't have a problem with barlowing my 2" 28mm ES68. In fact, if I wanted to spend the money, I could probably be perfectly happy with the 28mm ES68 and a couple of 2" Siebert barlows.

Dave


Dave, does the ES 28mm vignette in a barlow? I know my 28mm and 20mm Series 5000 did, but the 20mm ES 68 didn't. I'm now wondering if the Meade series 5000 68's and ES 68's are a bit different in lens design? Hmmmmm.

Cheers,


Mark,

That is an excellent question. I find that the 28mm ES68 with a 1.25" to 2" adapter doesn't seem to vignette in a regular barlow. At least the field stop is still clean and sharp. I've used it with 3x TV, 2.4x Dakin, and 1.5x Siebert barlows in this fashion. The adapter alters the magnification factor. The 28mm ES68 will vignette with the 1.25" to 2" adapter in a 2" powermate.

I have clear skies but it is frigid out. I wasn't going to go out, but since you asked this maybe I'll set up and take a quick look to give you some additional observations.

Dave

#21 johnnyha

johnnyha

    Fly Me to the Moon

  • *****
  • Posts: 6500
  • Joined: 12 Nov 2006
  • Loc: Sherman Oaks, CA

Posted 22 January 2013 - 07:00 PM

Dave, the 28mm ES 68 is a 2" eyepiece, I'm trying to figure out how you are using it with a 1.25" to 2" adapter? :question:

#22 russell23

russell23

    Skylab

  • *****
  • Posts: 4458
  • Joined: 31 May 2009
  • Loc: Upstate NY

Posted 22 January 2013 - 07:25 PM

Dave, the 28mm ES 68 is a 2" eyepiece, I'm trying to figure out how you are using it with a 1.25" to 2" adapter? :question:


The 1.25" to 2" adapter is a blue fireball adapter you can get from agenaastro:

http://agenaastro.co...ce-adapter.html

The barrel end of the adapter can drop into a 1.25" barlow and then the 28mm ES68 slides into the top of the adapter.

I just checked it with the 1.25" Dakin barlow and there was some very slight vignetting of the 28mm ES68.

Dave

#23 johnnyha

johnnyha

    Fly Me to the Moon

  • *****
  • Posts: 6500
  • Joined: 12 Nov 2006
  • Loc: Sherman Oaks, CA

Posted 22 January 2013 - 07:30 PM

Ah OK thanks Dave. Very strange looking beast!

#24 Scanning4Comets

Scanning4Comets

    Markus

  • *****
  • Posts: 13776
  • Joined: 26 Dec 2004
  • Loc: Canada

Posted 22 January 2013 - 07:33 PM

Actually, the Meade 2" 28mm SWA vignettes quite a lot in a 2" barlow. In that adapter, the 2" 28mm ES or ANY 2" 28mm EP will vignette like crazy in that adapter Dave.

Cheers,

#25 russell23

russell23

    Skylab

  • *****
  • Posts: 4458
  • Joined: 31 May 2009
  • Loc: Upstate NY

Posted 22 January 2013 - 09:00 PM

Actually, the Meade 2" 28mm SWA vignettes quite a lot in a 2" barlow. In that adapter, the 2" 28mm ES or ANY 2" 28mm EP will vignette like crazy in that adapter Dave.

Cheers,


Mark,

I just came in from checking for vignetting with 28mm ES68. Unfortunately, the only 2" barlow I have is a 2.4x 2" Dakin barlow which must be placed before the star diagonal to reach focus. I saw no vignetting of the 28mm ES68 with the 2" Dakin barlow.

Using the 1.25" to 2" adapter with the 1.25" Dakin barlow there was some very mild vignetting. I could see the field stop and it was not quite as sharp as unbarlowed and there was a VERY slight uneven fading of the light close to the field stop. Unless you look for the vignetting you won't even notice it. It is so mild I wasn't even sure I was seeing vignetting at first.

Keep in mind that the field stop of the 24mm ES68 is 27mm and the field stop of the 28mm ES68 is ~31mm. I've found that these 2" eyepieces that have slightly larger field stops than the maximimum 1.25" field stop do not show significant vignetting when you use them with a regular 1.25" barlow and a 1.25" to 2" adapter that is placed into the barlow. The adapter elevates the 2" eyepiece farther from the barlow and apparently reduces the vignetting in the process.

With the 1.25" 2.5x powermate there is significant vignetting with the 28mm ES68 and there is not even a hint of the field stop detectable.

Dave






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics