Saturday, September 28, 2013

At this point I'm going to post the information about my modified solar scope.

The scope utilizes the Etalon from my Coronado PST, an Energy Rejection filter (ERF) that is a Lunt 100mm ERF filter,  and a Coronado BF 15 blocking filter.  These items were all added to a Celestron 102GT 102mm refactor.  It should be noted that all of these pieces need to be installed in a modified scope for proper function and first and foremost SAFETY.  

The final version of my modified solar scope.    There are two focusers in this version.  The first focuser was for adjusting the position of the Etalon in the light cone, mostly for experimenting (This could be removed and a spacer installed.).  Then there is the Etalon, image focuser, blocking filter and the CCD camera.  The cooler under the scope is actually my battery box.  It contains two Gel cells in parallel with an accessory power socket for the power cord.  My high tech cardboard box works great for shading the laptop screen and I would replace it if I found anything handier.  :-)  Finally there is the clamp-on umbrella for keeping me out of the sun.

Since this picture was taken the focuser has been replaced with a Crawford style two speed focuser.  As i stated previously, this scope was assembled with help and advice from my friend Mike.   i have named this scope 'Cloud Buster' because I have been able to image the sun through thin clouds with it.

Mike has assembled a similar scope using a Celestron 102XLT refractor. (Not shown here.)
There is also a 2" twist lock adapter in the mix along with an Etalon to 2" focuser adapter made for me by Mike.

The ERF is mounted in front of the scope objective lens using O-Rings as spacers and a modified objective lens retainer ring.

For my modified solar scope I needed a solar finder so i modified a red dot finder for the purpose.  This finder works amazingly well.  Just line up the circle of sun light on the card and the sun is in the scopes field of view.

I have since replaced the original focuser with this focuser.  A great addition.

GSO 2" Linear Bearing Crayford Focuser for Refractors - Dual Speed (with 96.6mm Flange)

December 24, 2013 Update:
The new focuser is installed on my solar scope and the Etalon is now in the proper position in the light cone and can stay fixed at that location.  I haven't had the skies to test the new configuration yet but I will post an update as soon as that happens.

While having too much extra time on these cold and foggy winter days I decided to mount my SME 40 (Second Etalon for my PST.) to the dust cover of my 102GT.  While reducing the aperture size is a step back it would double stack my modified 102GT.  I also had another unmodified 102GT that I can mount this on and with the addition of my BF 15, I would have basically a 40mm solar scope with a very long focal length.  I have lined out this statement as I have found out an additional ERF would be needed to safely use this Etalon with my unmodified scope.  Always safety first in solar observation.

After discussing with Mike about how to remotely adjust that Etalon that will be a very long reach while imaging, I decided to try to recycle my remote focuser servo setup from my PST.  As you can see, this is a temporary setup.  Honest. :-)

As it was on the PST.

I decide to abandon the servo mounted to the telescope tube concept and make the whole assembly removable with the dust cap mounted etalon.  When I switch the Etalon from my modified 102GT to the unmodified 102GT it will be ready to go, with the addition of the BF 15 blocking filter to the unmodified scope, that is.


Bill Griffith and Mike Bridges said...

Excellent job on your Cloudbuster build Bill , the results you have been able to obtain with it speak volumes !
You give me too much credit Bill there is nothing here that I have invented , this is just available information that I have followed and shared . I will add my build today

Bob Johnston said...

Great blog Bill and Mike!
I have a question for you Bill.
The Celestron Omni 102 I picked up is generally for this mod only. I have no reservations of cutting into her to achieve the results I'm hoping for. Now..I read over on Solar Chat that you did have to cut two inches off the length of your OTA. Did you find the 2" too much or was it just about right? I ask as I have made arrangements at work to use a bandsaw that more than adequate to slice through the tube. Can I use the scope then as it was designed for by then using a 2" extension after the length is reduced??