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Equipment Discussions >> Equipment

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michael_m
sage
*****

Reged: 11/16/10

Loc: Mount Vernon, Wa
Re: Barlow vs. Powermate? new [Re: ThreeD]
      #4931219 - 11/23/11 12:39 PM

Although I had not seen that "point 4" yet while researching, which I have now done, I did not doubt you ThreeD. The riser is more about getting the fully racked in focuser out of the inside of the UTA and also the full focuser travel for whatever I might do in the future. Thanks for your assurance from experience and your input.

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Startraffic
professor emeritus
*****

Reged: 02/12/06

Loc: Lat. 39.143345, Long. -77.1748...
Re: Barlow vs. Powermate? new [Re: ThreeD]
      #5518260 - 11/13/12 04:39 PM

MaestroMyth,
I have 2 Powermates, both 2" a 2x & 4x. I don't care for the views through a Barlow. They are however, pretty cheap ones. Something that no-one has mentioned, Powermates are significantly heavier, You'll need a solid focuser to carry one. I replaced a GSO I had on my SNT with a Moonlite, much better.

Clear Dark Skies
Startraffic
39.138274 -77.168898
Alt 518ft ASL


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Widespread
professor emeritus


Reged: 05/11/11

Loc: Bowling Green, Kentucky
Re: Barlow vs. Powermate? new [Re: Startraffic]
      #5670222 - 02/09/13 07:23 AM

Thank you for a very interesting discussion. Since some time has elapsed since the last post, I hope folks don't mind if I resurrect it and ask some related questions.

I recently bought a smaller refractor, and, unsurprisingly, I find that the eyepieces I had for my 8 inch SCT do not give high enough magnification for planets.

I have been thinking of upgrading my Celestron Barlow that came bundled with my SCT. Would a TeleVue 2x Barlow or PowerMate (or other product) give noticeably improved performance?

This is for a 90mm F7 Refractor. The highest magnification ocular that I have is 8.8ES82. (I also have 11mm and 14mm that could be barlowed.)

But I am not committed to the Barlow route. I guess mine is actually more of a general question regarding eyepiece strategy for this unfamiliar focal length.

Also I'm curious as to the purpose of the 2 inch Barlow or PowerMate discussed above. Intuitively, it seems like this type of amplifier would be used more for achieving high magnifications. But I'm sure I'm missing something. Any remediation of my benightedness would be greatly appreciated. Maybe people use them for the 9mm Ethos?

Cheers,
David


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David Knisely
Postmaster
*****

Reged: 04/19/04

Loc: southeastern Nebraska
Re: Barlow vs. Powermate? new [Re: Widespread]
      #5670814 - 02/09/13 01:54 PM

Quote:

Thank you for a very interesting discussion. Since some time has elapsed since the last post, I hope folks don't mind if I resurrect it and ask some related questions.

I recently bought a smaller refractor, and, unsurprisingly, I find that the eyepieces I had for my 8 inch SCT do not give high enough magnification for planets.

I have been thinking of upgrading my Celestron Barlow that came bundled with my SCT. Would a TeleVue 2x Barlow or PowerMate (or other product) give noticeably improved performance?

This is for a 90mm F7 Refractor. The highest magnification ocular that I have is 8.8ES82. (I also have 11mm and 14mm that could be barlowed.)

But I am not committed to the Barlow route. I guess mine is actually more of a general question regarding eyepiece strategy for this unfamiliar focal length.

Also I'm curious as to the purpose of the 2 inch Barlow or PowerMate discussed above. Intuitively, it seems like this type of amplifier would be used more for achieving high magnifications. But I'm sure I'm missing something. Any remediation of my benightedness would be greatly appreciated. Maybe people use them for the 9mm Ethos?

Cheers,
David




The Barlow or Powermate would give you very good performance as good as or perhaps slightly better than the Celestron Barlow. With a Barlow, the eye relief of an eyepiece can be maintained or increased slightly which can help with some eyepieces that don't have a lot to begin with and hurt with others if the Barlow puts in too much eye relief. Powermates also maintain eye relief, but they don't increase it. As for why 2" Barlows or Powermates are used, that is for use with longer focal length 2" barrel eyepieces. The use of these is especially prevalent in the larger Dobsonians, where longer focal length wider-field eyepieces are often used and higher powers are desired. Clear skies to you.


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Widespread
professor emeritus


Reged: 05/11/11

Loc: Bowling Green, Kentucky
Re: Barlow vs. Powermate? new [Re: David Knisely]
      #5670933 - 02/09/13 03:46 PM

Thank you, David. As good or slightly better... It sounds like any improvement would be minor.

I think I understand what you are saying about 2" barlows: 2" finder EPs to locate a target, then Barlow for a better look, e.g.

Cheers,
David


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Jon Isaacs
Postmaster
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Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: Barlow vs. Powermate? new [Re: Widespread]
      #5671877 - 02/10/13 06:44 AM

Quote:

Thank you, David. As good or slightly better... It sounds like any improvement would be minor.

I think I understand what you are saying about 2" barlows: 2" finder EPs to locate a target, then Barlow for a better look, e.g.

Cheers,
David




David:

I have two older Celestron Shorty Barlows, I use them with some pretty good eyepieces and telescopes, I have other Barlows but the Celestron Shorty's are my favorites. I only use them for high magnification, when 3.5 mm Nagler or 4mm TMB Planetary is not enough, I think your current Barlow will do a good job.

Jon


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Widespread
professor emeritus


Reged: 05/11/11

Loc: Bowling Green, Kentucky
Re: Barlow vs. Powermate? new [Re: Jon Isaacs]
      #5672044 - 02/10/13 09:48 AM

Hi Jon,

It's good to hear that I don't need to spend more for an expensive diagonal.

Funny you should mention the TMB 4mm. In fact, I was trying to decide whether to get one of those; or a better Barlow; or just stick with my current Barlow.

I'm now leaning against an expensive Barlow, and figured that my 8.8mm, when Barlowed, would be about as high mag as 90mm could handle.

Those TMBs look nice, though. How much improvement could one expect from the 4mm and 5mm planetaries, compared with Barlowing my 8.8 and 11mm ES82s?

Best,
David


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johnnyha
Postmaster
*****

Reged: 11/12/06

Loc: Sherman Oaks, CA
Re: Barlow vs. Powermate? new [Re: Widespread]
      #5672852 - 02/10/13 06:46 PM

I'm pretty sure your ES 82s when barlowed will be of somewhat higher quality than the TMBs. I think you're good actually. The TMBs are nice for the price but they are not premium optics like the ES 82s. Your ES82s will barlow well at 2X giving you a *perfect* progression from 14, 11, 8.8mm to 7, 5.5, and 4.4mm.

If you have any doubts about the Celestron barlow then you can grab a nice used 1.25" 2X TV barlow for around $70.


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Motokid600
super member


Reged: 06/27/10

Loc: Berlin, New Jersey
Re: Barlow vs. Powermate? new [Re: michael_m]
      #5674069 - 02/11/13 01:28 PM

Imaging the planets is something I've been wanting to get into. I've got a 1000d in prime focus behind a CPC11 and I find the magnification is not significant enough for when it comes to planets. Im not to savy with magnigication details so ill say this. At my current focal length I can just barely fit the whole moon into my camera's FoV. Not enough.. so with backyard EoS I can record via the live view. The power mate seems to be the way to go. But which one? 2x or 4x. My goal one day is to be able to achieve detail on the Jovian moons. So would a 2x do the job? I realize a 4x would be at the mercy of the atmosphere, but surprisingly this small, light polluted town of mine seems to be blessed with some stable air above it.

Edited by Motokid600 (02/11/13 01:34 PM)


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Jim Romanski
Carpal Tunnel
*****

Reged: 01/02/05

Loc: Guilford, Connecticut
Re: Barlow vs. Powermate? new [Re: Motokid600]
      #5674768 - 02/11/13 08:38 PM

I've read that planetary imagers will stack Powermates to get higher maginfications. So I guess you could get a 2X and see if it's enough. If not you could get another or a 4X then you'd have 2X, 4X and 6X (or maybe it would be 8X?).

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Jim Romanski
Carpal Tunnel
*****

Reged: 01/02/05

Loc: Guilford, Connecticut
Re: Barlow vs. Powermate? new [Re: MaestroMyth]
      #5674776 - 02/11/13 08:45 PM

I have both 2" Powermates the 2X and 4X. I bought them after buying a short focal length refractor. They give me all kinds of magnifications and with any of my eyepieces. I thought I might get into planetary imaging with them as well though I haven't yet.

I also bought the older Televue 1.8X 1.25" barlow. I found that I wanted a smaller magnifier to use with smaller scopes and eyepieces. Also, I wanted the 1.8X in order to get a differnt variety of magnifications.

They all work very well.


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Jon Isaacs
Postmaster
*****

Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: Barlow vs. Powermate? new [Re: Motokid600]
      #5675302 - 02/12/13 06:22 AM

Quote:

Imaging the planets is something I've been wanting to get into. I've got a 1000d in prime focus behind a CPC11 and I find the magnification is not significant enough for when it comes to planets. Im not to savy with magnigication details so ill say this. At my current focal length I can just barely fit the whole moon into my camera's FoV. Not enough.. so with backyard EoS I can record via the live view. The power mate seems to be the way to go. But which one? 2x or 4x. My goal one day is to be able to achieve detail on the Jovian moons. So would a 2x do the job? I realize a 4x would be at the mercy of the atmosphere, but surprisingly this small, light polluted town of mine seems to be blessed with some stable air above it.




From what I see, planetary imagers are using modified webcam technology and image processing techniques like stacking to produce the fantastic photos of Jupiter and Saturn. One does not need a large frame size because one is limited by the resolution of the scope, only so many pixels are needed. Jupiter is only about 40 arc-seconds in diameter if you are oversampling and using 0.25 arc-seconds/pixel, this is only 160 pixels x 160x pixels. They key is transferring at 30 or 60 frames per second uncompressed video, getting a lot of data and then processing it to increase the signal to noise ratio.

Jon


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simon j poole
member


Reged: 02/11/13

Loc: UK
Re: Barlow vs. Powermate? new [Re: Jon Isaacs]
      #5677929 - 02/13/13 04:07 PM

I have 2x & 3x tv barlows, 2.5x powermate! There all very good performers but the tv 3x barlow which is a two element design produces a slightly more detailed image imho when im planetary imaging. Regards Simon.

Edited by simon j poole (02/13/13 04:13 PM)


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Jack Morris
member


Reged: 11/23/12

Loc: Louisiana
Re: Barlow vs. Powermate? new [Re: simon j poole]
      #5678850 - 02/14/13 06:48 AM

I have learned a lot from this discussion, thanks everyone. Does anyone care to comment on how the Explore Scientific "Focal Extenders" fit in here?

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MikeBOKC
Post Laureate
*****

Reged: 05/10/10

Loc: Oklahoma City, OK
Re: Barlow vs. Powermate? [Re: Jack Morris]
      #5678957 - 02/14/13 08:37 AM

I have the 2 inch ES barlow/FE and it seems to work very well. Don't use a barlow that often, but images are very comparable to that I get in the 2.5 1.25 Powermate.

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Jim Romanski
Carpal Tunnel
*****

Reged: 01/02/05

Loc: Guilford, Connecticut
Re: Barlow vs. Powermate? new [Re: Jon Isaacs]
      #5681806 - 02/15/13 03:39 PM

Quote:

From what I see, planetary imagers are using modified webcam technology and image processing techniques like stacking to produce the fantastic photos of Jupiter and Saturn. One does not need a large frame size because one is limited by the resolution of the scope, only so many pixels are needed. Jupiter is only about 40 arc-seconds in diameter if you are oversampling and using 0.25 arc-seconds/pixel, this is only 160 pixels x 160x pixels. They key is transferring at 30 or 60 frames per second uncompressed video, getting a lot of data and then processing it to increase the signal to noise ratio.

Jon



I've dabbled with this kind of webcam planetary imaging a little bit (see my avatar). But I know some of the guys who do outstanding work use other gear and have great results. Check out Paul Hyndman's site and you'll see he mentions using Powermates for a lot of his high power imaging.
www.astro-nut.com


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