Jump to content


Photo

Barlow vs. Powermate?

  • Please log in to reply
35 replies to this topic

#26 Jon Isaacs

Jon Isaacs

    ISS

  • *****
  • Posts: 44020
  • Joined: 16 Jun 2004
  • Loc: San Diego and Boulevard, CA

Posted 10 February 2013 - 06:44 AM

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

#27 Widespread

Widespread

    Viking 1

  • -----
  • Posts: 636
  • Joined: 11 May 2011
  • Loc: Bowling Green, Kentucky

Posted 10 February 2013 - 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

#28 johnnyha

johnnyha

    Fly Me to the Moon

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

Posted 10 February 2013 - 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.

#29 Motokid600

Motokid600

    Vostok 1

  • -----
  • Posts: 196
  • Joined: 27 Jun 2010
  • Loc: Berlin, New Jersey

Posted 11 February 2013 - 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.

#30 Jim Romanski

Jim Romanski

    Vanguard

  • *****
  • Posts: 2254
  • Joined: 02 Jan 2005
  • Loc: Guilford, Connecticut

Posted 11 February 2013 - 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?).

#31 Jim Romanski

Jim Romanski

    Vanguard

  • *****
  • Posts: 2254
  • Joined: 02 Jan 2005
  • Loc: Guilford, Connecticut

Posted 11 February 2013 - 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.

#32 Jon Isaacs

Jon Isaacs

    ISS

  • *****
  • Posts: 44020
  • Joined: 16 Jun 2004
  • Loc: San Diego and Boulevard, CA

Posted 12 February 2013 - 06:22 AM

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

#33 simon j poole

simon j poole

    Sputnik

  • -----
  • Posts: 32
  • Joined: 11 Feb 2013
  • Loc: UK

Posted 13 February 2013 - 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.

#34 Jack Morris

Jack Morris

    Sputnik

  • -----
  • Posts: 38
  • Joined: 23 Nov 2012
  • Loc: Louisiana

Posted 14 February 2013 - 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?

#35 MikeBOKC

MikeBOKC

    Aurora

  • *****
  • Posts: 4537
  • Joined: 10 May 2010
  • Loc: Oklahoma City, OK

Posted 14 February 2013 - 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.

#36 Jim Romanski

Jim Romanski

    Vanguard

  • *****
  • Posts: 2254
  • Joined: 02 Jan 2005
  • Loc: Guilford, Connecticut

Posted 15 February 2013 - 03:39 PM

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






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics