Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

Removing the Powermate body

  • Please log in to reply
14 replies to this topic

#1 thecelloronin

thecelloronin

    Apollo

  • *****
  • topic starter
  • Posts: 1,418
  • Joined: 10 Dec 2020
  • Loc: Lowcountry, SC

Posted 16 April 2024 - 11:24 PM

I read this thread about how it’s possible to remove the 2X Powermate’s body and attach it to things with a T2 adapater.

 

https://www.cloudyni...w/#entry3971419
 

However, I’m confused as to why this poster says the power of the powermate is 1.6x. I thought the whole charm of these telecentric designs is that it doesn’t matter where you place it along the optical train, they stay parafocal and don’t change powers like a barlow.

 

Am I out to lunch here?



#2 MisterDan

MisterDan

    Surveyor 1

  • *****
  • Posts: 1,727
  • Joined: 20 Jun 2014
  • Loc: Colorado

Posted 16 April 2024 - 11:39 PM

The magnification variance (with distance) with the 2x Powermate is - according to this chart - effectively nil.  Other Powermates do indeed vary.

 

https://www.televue....?id=53&Tab=_app

 

I can't speak to the 1.6x claim, unless that is based on typical Barlow variance (with distance), which don't apply to the Powermates.

 

Best wishes and kind regards.

Dan


  • thecelloronin likes this

#3 betacygni

betacygni

    Mercury-Atlas

  • *****
  • Posts: 2,664
  • Joined: 06 Feb 2011

Posted 17 April 2024 - 12:56 AM

Think the poster in that thread was simply wrong. Powermates change very little in power with distance changes (except the 5x powermate it seems), at least relative to barlows which change a lot.
  • CrazyPanda and thecelloronin like this

#4 Starman1

Starman1

    Stargeezer

  • *****
  • Posts: 65,465
  • Joined: 23 Jun 2003
  • Loc: Los Angeles

Posted 17 April 2024 - 08:48 AM

I read this thread about how it’s possible to remove the 2X Powermate’s body and attach it to things with a T2 adapater.

 

https://www.cloudyni...w/#entry3971419
 

However, I’m confused as to why this poster says the power of the powermate is 1.6x. I thought the whole charm of these telecentric designs is that it doesn’t matter where you place it along the optical train, they stay parafocal and don’t change powers like a barlow.

 

Am I out to lunch here?

Tele Vue makes T2 adapters for all of their PowerMates, whether 1.25" (2.5x and 5x) or 2" (2x and 4x)

There is no 1.6x PowerMate.


  • simon99 likes this

#5 Doug Culbertson

Doug Culbertson

    Voyager 1

  • *****
  • Posts: 12,155
  • Joined: 06 Jan 2005
  • Loc: N. Florida

Posted 17 April 2024 - 08:57 AM

I read this thread about how it’s possible to remove the 2X Powermate’s body and attach it to things with a T2 adapater.

 

https://www.cloudyni...w/#entry3971419
 

However, I’m confused as to why this poster says the power of the powermate is 1.6x. I thought the whole charm of these telecentric designs is that it doesn’t matter where you place it along the optical train, they stay parafocal and don’t change powers like a barlow.

 

Am I out to lunch here?

He is talkiing about attaching the Powermate with T-2 ring directly to the end of a binoviewer; specifically a Baader Mark V binoviewer. When attached directly to a binoviewer in this manner the Powermate acts at a slightly lower power. This is due to the light path of the binoviewer. For example, when I attach my 2.5x Powermate to my CZAS binoviewer it works at somewhere around 2.1x. This has been verified several times in the binoviewers forum. 



#6 Starman1

Starman1

    Stargeezer

  • *****
  • Posts: 65,465
  • Joined: 23 Jun 2003
  • Loc: Los Angeles

Posted 17 April 2024 - 09:04 AM

He is talkiing about attaching the Powermate with T-2 ring directly to the end of a binoviewer; specifically a Baader Mark V binoviewer. When attached directly to a binoviewer in this manner the Powermate acts at a slightly lower power. This is due to the light path of the binoviewer. For example, when I attach my 2.5x Powermate to my CZAS binoviewer it works at somewhere around 2.1x. This has been verified several times in the binoviewers forum. 

How is that possible?  Does the binoviewer act like a focal reducer?



#7 Doug Culbertson

Doug Culbertson

    Voyager 1

  • *****
  • Posts: 12,155
  • Joined: 06 Jan 2005
  • Loc: N. Florida

Posted 17 April 2024 - 09:22 AM

How is that possible?  Does the binoviewer act like a focal reducer?

Sorry, I'm lousy at math so I can't explain it. Something to do with the long light path of the binoviewer. I do know this, I directly compared the TV 2x BV corrector to the 2.5x Powermate in my former Baader Maxbright II  binoviewer and it was virtually identical in magnification and fov. Drift timing with my current CZAS binoviewer and a pair of 24mm Brandons shows it to be right around 2x, perhaps a bit more, but not 2.5x. 

 

Go browse through the binoviewer forum. Eddgie is the one who alerted me to this fact, and he can explain it much better than my rudimentary understaning of it. 

 

As I said, there have been several mentions of this in the Binoviewers forum

 

https://www.cloudyni...kay/?p=13168220

 

https://www.cloudyni...ase/?p=13267093

 

https://www.cloudyni...ets/?p=13184622

 

Edit to remove double link. 


Edited by Doug Culbertson, 17 April 2024 - 09:33 AM.

  • betacygni likes this

#8 betacygni

betacygni

    Mercury-Atlas

  • *****
  • Posts: 2,664
  • Joined: 06 Feb 2011

Posted 17 April 2024 - 10:12 AM

How is that possible? Does the binoviewer act like a focal reducer?

If you check the Televue chart linked in a prior post the 2.5x Powermate has a reduction in power as the distance between it and the eyepiece increases. Binoviewers obviously make this distance substantial. That said I have no idea why the 2.5x powermate has this behavior, it appears to be the only powermate that reduces with distance, the others increase to various degrees.
  • Starman1 and Thomas_M44 like this

#9 thecelloronin

thecelloronin

    Apollo

  • *****
  • topic starter
  • Posts: 1,418
  • Joined: 10 Dec 2020
  • Loc: Lowcountry, SC

Posted 21 April 2024 - 12:55 AM

Tele Vue makes T2 adapters for all of their PowerMates, whether 1.25" (2.5x and 5x) or 2" (2x and 4x)

There is no 1.6x PowerMate.

does this mean that the 2.5x 1.25" PM also unscrews from its body?



#10 Starman1

Starman1

    Stargeezer

  • *****
  • Posts: 65,465
  • Joined: 23 Jun 2003
  • Loc: Los Angeles

Posted 21 April 2024 - 01:17 AM

does this mean that the 2.5x 1.25" PM also unscrews from its body?

https://www.televue....id=53&Tab=_back

Yes, it separates at the line above the 2.5x lettering.

The T-adapter threads on there.


  • thecelloronin likes this

#11 Doug Culbertson

Doug Culbertson

    Voyager 1

  • *****
  • Posts: 12,155
  • Joined: 06 Jan 2005
  • Loc: N. Florida

Posted 21 April 2024 - 11:37 AM

Parts separated and lower part with T2 ring.

Attached Thumbnails

  • IMG_2965.jpeg
  • IMG_2964.jpeg


#12 Doug Culbertson

Doug Culbertson

    Voyager 1

  • *****
  • Posts: 12,155
  • Joined: 06 Jan 2005
  • Loc: N. Florida

Posted 21 April 2024 - 11:40 AM

2.5x PM attached to my CZAS binoviewer using the T2 ring.

Attached Thumbnails

  • IMG_2356.jpeg

Edited by Doug Culbertson, 21 April 2024 - 11:40 AM.


#13 junomike

junomike

    ISS

  • *****
  • Administrators
  • Posts: 22,517
  • Joined: 07 Sep 2009
  • Loc: Ontario

Posted 21 April 2024 - 03:17 PM

As I recall some earlier Powermates aren't compatible with the T2 Ring as the  separation was between the body and chrome barrel (as opposed to newer one's that separate between the body housing).

 

Non compatible older style

 

Compatible newer style


  • Starman1 and Doug Culbertson like this

#14 betacygni

betacygni

    Mercury-Atlas

  • *****
  • Posts: 2,664
  • Joined: 06 Feb 2011

Posted 21 April 2024 - 03:18 PM

2.5x PM attached to my CZAS binoviewer using the T2 ring.

Have you ever tested how close the 2.5x powermate makes the CZAS being parfocal to a mono eyepiece?Have been very curious but haven’t went the route of buying one to find out.

I have the uncomfirmed theory that a standard glasspath would introduce prism aberrations in a mirrored binoviewer that they are designed to correct in a prism model, which would make the 2.5x powermate the best CZAS option. But some of my scopes are back focus challenged and need nearly full light path compensation as compared to mono.

Edited by betacygni, 21 April 2024 - 03:24 PM.


#15 Doug Culbertson

Doug Culbertson

    Voyager 1

  • *****
  • Posts: 12,155
  • Joined: 06 Jan 2005
  • Loc: N. Florida

Posted 21 April 2024 - 04:03 PM

Have you ever tested how close the 2.5x powermate makes the CZAS being parfocal to a mono eyepiece?Have been very curious but haven’t went the route of buying one to find out.

I have the uncomfirmed theory that a standard glasspath would introduce prism aberrations in a mirrored binoviewer that they are designed to correct in a prism model, which would make the 2.5x powermate the best CZAS option. But some of my scopes are back focus challenged and need nearly full light path compensation as compared to mono.

You know, I have not tried that. For some reason, it never entered my mind to compare it to a mono eyepiece, though I suspect that it would not be parfocal with eyepieces in a binoviewer even with a PM. 

 

I have the same unconfirmed theory as you regarding a GPC in a mirror based binoviewer. I've mentioned that a couple of times in the Binoviewers forum, but nobody has confirmed or denied it. When I bought this binoviewer from Denis I asked about a GPC and he said that he would not use one, but didn't elaborate. 


  • betacygni likes this


CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics