Return to the Cloudy Nights Telescope Reviews home page


Telescope Specific Forums >> Celestron NexStar

Pages: 1
James Cunningham
Post Laureate
*****

Reged: 08/07/10

Loc: Maryland
Herschel Wedge on SCT? new
      #5754208 - 03/24/13 02:45 PM

Can you use a Herschel Wedge on an SCT? Thanks
Jim


Post Extras: Print Post   Remind Me!   Notify Moderator  
zippeee
sage


Reged: 12/27/10

Loc: Alberta, Canada
Re: Herschel Wedge on SCT? new [Re: James Cunningham]
      #5754298 - 03/24/13 03:30 PM

No

As I understand it, unfiltered sunlight (especially the amount that can be collected with 11") is not intended to be focused on internal mirrors. There would be too much heat build-up on the secondary, apart from other things I'm sure.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Peter in Reno
Postmaster
*****

Reged: 07/15/08

Loc: Reno, NV
Re: Herschel Wedge on SCT? new [Re: zippeee]
      #5754319 - 03/24/13 03:41 PM

Look at this:

http://en.wikipedia.org/wiki/Herschel_wedge

It says that it cannot be used for reflecting scopes and an SCT is a reflecting (mirrors) scope. It's best for refractors.

Peter


Post Extras: Print Post   Remind Me!   Notify Moderator  
HeyJP
sage


Reged: 12/11/10

Loc: Boulder, CO
Re: Herschel Wedge on SCT? new [Re: Peter in Reno]
      #5755131 - 03/24/13 10:32 PM

Not a good idea for a lot of reasons. On SCT or reflector I would always use a big-*BLEEP* solar filter in front of everything. I like my eyes.

Jim


Post Extras: Print Post   Remind Me!   Notify Moderator  
rmollise
Postmaster
*****

Reged: 07/06/07

Re: Herschel Wedge on SCT? new [Re: James Cunningham]
      #5756412 - 03/25/13 03:24 PM

Quote:

Can you use a Herschel Wedge on an SCT? Thanks
Jim




Nope, not if you are smart. You will likely damage the scope--and badly. Stick to full aperture solar filters.

Oh, and Mr. Jim means "big @ss" solar filter...

Edited by rmollise (03/25/13 03:26 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
HeyJP
sage


Reged: 12/11/10

Loc: Boulder, CO
Re: Herschel Wedge on SCT? [Re: rmollise]
      #5757433 - 03/26/13 02:49 AM

Uncle Rod,

That's exactly what I meant. Takes another southerner to interpret what gets lost in translation.

Jim (originally from Tennessee)


Post Extras: Print Post   Remind Me!   Notify Moderator  
btieman
scholastic sledgehammer


Reged: 07/24/08

Re: Herschel Wedge on SCT? new [Re: HeyJP]
      #5796378 - 04/13/13 10:47 AM

Hmm...I wonder if a full aperture solar filter as a pre-filter to knock down the heat would allow it to be safe? Or are there reasons beyond heat why a wedge won't work with a reflector...

Post Extras: Print Post   Remind Me!   Notify Moderator  
Starhawk
Space Ranger
*****

Reged: 09/16/08

Loc: Tucson, Arizona
Re: Herschel Wedge on SCT? new [Re: btieman]
      #5796657 - 04/13/13 01:39 PM

Do not attempt this. Lots of awful things can go wrong.

First, the wedges aren't made for giant scopes, so you'll risk destroying your eyesight forever on that first peek. There would seem to be countermeasures to this, but they are flawed.

Specifically, if you put a full opaque cover over the entire front of the telescope with a cutout within the stated safe diameter range for the wedge, then that could appear to be safe for the wedge. However, things like the baffles, lubricants, paints, mirrors, and optical coatings aren't intended for this and can outgas and fog items, crack, melt, or flake off.

Now, there is a dirty little secret: the Baader safety film sold by Astro-Physics in sheets or Kendrick in ready to use filters is safe, inexpensive, and produces absolutely fantastic images. I made a filter for my C5 out of a round cardboard box I found at Michael's craft supply and made an off axis filter for my C8 out of a round gift box I found at Big Lots (and some people here accuse me of being elitist).

Paint your filter cover gloss white wherever the sun can hit it and make sure it goes on very snug and secure (you can use art foam sheets to decrease the diameter so your filter has no chance if being knocked off, blown off, or otherwise being removed by a deliberate effort which can't happen without being noticed by the observer before it's too late).

-Rich


Post Extras: Print Post   Remind Me!   Notify Moderator  
Pages: 1


Extra information
8 registered and 19 anonymous users are browsing this forum.

Moderator:  Brian Risley, panhard, Mitchell Duke, mayidunk 

Print Thread

Forum Permissions
      You cannot start new topics
      You cannot reply to topics
      HTML is disabled
      UBBCode is enabled


Thread views: 880

Jump to

CN Forums Home




Cloudy Nights Sponsor: Astronomics