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Author Topic: El Cheapo 90mm Ha Solar telescope  (Read 10463 times)

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Offline michaeloconnell78

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Re: El Cheapo 90mm Ha Solar telescope
« Reply #15 on: 19:08:36, 25 April, 2008 »
Only problem is the secondary obstruction.
However, as someone with a double-stack Maxscope 40, I'll be keeping an eye on this thread.  ;)
Regards,
Michael
www.astroshot.com
Gemini G41 Observatory+ Mount; 16" LX200 SCT, TEC140; Pentax75SDHF; PST CaK, PST Ha.

Offline Merlin66

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Re: El Cheapo 90mm Ha Solar telescope
« Reply #16 on: 19:12:09, 25 April, 2008 »
Michael,
That might actually work in our favour! Reduce the amount of "stray" light!!!!
C11, C9.25 SCT, 4" Genesis, NEQ6pro, modded 1000D,  ATik314L+, DMK41AF04, SM60DS/BF15, and Spectroscopes (many!).
http://tech.groups.yahoo.com/group/astronomical_spectroscopy/
"Astronomical Spectroscopy for Amateurs", "Grating Spectroscopes-How to Use them" -Springer

Offline michaeloconnell78

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Re: El Cheapo 90mm Ha Solar telescope
« Reply #17 on: 19:53:55, 25 April, 2008 »
If using the SM40, you'll want the cone of light to be close to 40mm in diameter whe it meets the etalon.
The light will need to be parallel before it hits the SM40, so a 2" powermate or similar will be required.
FWIW, the central obstruction on the SM40 is 12mm, which gives a central obstruction ratio of 30%.
Regards,
Michael
www.astroshot.com
Gemini G41 Observatory+ Mount; 16" LX200 SCT, TEC140; Pentax75SDHF; PST CaK, PST Ha.

Offline colinsk

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Re: El Cheapo 90mm Ha Solar telescope
« Reply #18 on: 22:02:02, 25 April, 2008 »
30% wow, I think two PST etalons would be better.

Offline colinsk

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Re: El Cheapo 90mm Ha Solar telescope
« Reply #19 on: 05:37:34, 27 April, 2008 »
I recieved my 90mm f/10 objective and ERFs today. Thank you for the ERFs Ken! Now I just need to find a nice tube...

Offline colinsk

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Re: El Cheapo 90mm Ha Solar telescope
« Reply #20 on: 02:39:34, 29 April, 2008 »
Ok, I have the ERFs and the objective. I measured the mounting cell and came up with this sketch:

[attachment deleted by admin]

Offline colinsk

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Re: El Cheapo 90mm Ha Solar telescope
« Reply #21 on: 02:43:53, 29 April, 2008 »
It looks like this cell was designed to be on 110mm OD tubing with a 3mm wall. I can't get that here. The four dogs would deform and provide a tight fit. Perhaps they would have to be worked slightly. I can have a piece of tubing made or get one that is pretty close and work with the cell. This company will make any tubing:

http://www.parallaxinstruments.com/tube.htm

But, I might be able to make the 4" .050" wall tubing work.

Offline michaeloconnell78

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Re: El Cheapo 90mm Ha Solar telescope
« Reply #22 on: 18:35:57, 29 April, 2008 »
I recieved my 90mm f/10 objective and ERFs today. Thank you for the ERFs Ken! Now I just need to find a nice tube...

Mind me asking what ERFs you got?
Regards,
Michael
www.astroshot.com
Gemini G41 Observatory+ Mount; 16" LX200 SCT, TEC140; Pentax75SDHF; PST CaK, PST Ha.

Offline colinsk

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Re: El Cheapo 90mm Ha Solar telescope
« Reply #23 on: 21:42:51, 29 April, 2008 »
Merlin66 (Thank you Ken!) sent me a Wratten and a Rosco UV filter. I am not as confident in them as the Baader but my Baader dealer is telling me it wil be months before I can get one and I want to crash ahead.

Offline Merlin66

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Re: El Cheapo 90mm Ha Solar telescope
« Reply #24 on: 08:01:56, 30 April, 2008 »
Just a quick note:
Colin, the bandwidth of the ERF Combo is identical to the Baader.
For the 90mm objective; I'm making a square tube (104mm inside) from 6mm custom wood, easy to build!
I'll allow for a 45mm -185 Barlow ( again from Surplus Shed) to test out the SM40 project.
C11, C9.25 SCT, 4" Genesis, NEQ6pro, modded 1000D,  ATik314L+, DMK41AF04, SM60DS/BF15, and Spectroscopes (many!).
http://tech.groups.yahoo.com/group/astronomical_spectroscopy/
"Astronomical Spectroscopy for Amateurs", "Grating Spectroscopes-How to Use them" -Springer

Offline colinsk

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Re: El Cheapo 90mm Ha Solar telescope
« Reply #25 on: 16:16:20, 30 April, 2008 »
I have worked with Rosco products a lot. I was a theatrical lighting designer in the evenings for 10 years and 30 some odd shows. The way we looked at transmission curves was very different. It was not as critical as this application. I have no reason to mistrust their data but I still do because of the industry.

But, another thing I think about, the graphs look like they go to zero but with something as bright as the sun we don't really know. It is indistinguishable on these graphs between 1% transmission and .0001% transmission. I am hoping I can get all of the off band light to .0001%! (OD6).

I bought a large grating on ebay years ago to measure mode hoping in lasers and I don't have any idea of its specs but I am going to dig it out and see if with a grating and a laser power meter I can measure the IR and UV performance of the filters.

I took the lens cell apart last night. It is an air spaced design so if you do it look for the small spacers as you get it apart. I am going to blacken the edges of the lenses. My lens set was marked for the best rotation for reassembly so if your's is not make a mark before the lenses get rotated relative to each other. Getting this back together is not an easy task because of the collimation issues. Be warned...

I have noticed that blackening the edges in my EPs helps the contrast a lot so I though I would do it to the objective while I wait on parts. I use Krylon Ultra Flat Black sprayed into the lid and brushed on with an artist's brush.

Offline Merlin66

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Re: El Cheapo 90mm Ha Solar telescope
« Reply #26 on: 05:58:15, 12 May, 2008 »
Ok, got back safely from Australia. While I was over there I managed to get a couple of adapters machined.
One is a 56mm female to a SCT 2" thread; this allows me to "lock" my spectroscope to the ED80 ( I was using a 2" prime focus adaptor but found too much slop!)
The other is a 50mm female to SCT; this fits the rear thread of the PST etalon and allows me to directly mount a SCT micro-focusser and any other standard SCT accessories ( ie flip mirror etc)
Also made up an IKEA "knock down" kit of parts for the El cheapo tube. It's from 6mm thick customwood, to make a square tube 104mm inside by 400mm long and a second section 92mm square by 400mm long which slides inside. This will allow me to accurately position the etalon etc using the Surplus Shed 90mm objective; it also allows provision for the mounting of a barlow lens to give a parallel beam into the SM40 filter ( for trials at least!)
I'll post a few pictures of the kit and give progress updates over the next few days.
C11, C9.25 SCT, 4" Genesis, NEQ6pro, modded 1000D,  ATik314L+, DMK41AF04, SM60DS/BF15, and Spectroscopes (many!).
http://tech.groups.yahoo.com/group/astronomical_spectroscopy/
"Astronomical Spectroscopy for Amateurs", "Grating Spectroscopes-How to Use them" -Springer

Offline colinsk

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Re: El Cheapo 90mm Ha Solar telescope
« Reply #27 on: 17:04:29, 13 May, 2008 »
That is great news!

Offline Merlin66

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Re: El Cheapo 90mm Ha Solar telescope
« Reply #28 on: 09:15:06, 14 May, 2008 »
Here's a couple of photos of the Kit.
The first shows the new adaptors I machined up. On the RHS is the ED80 to SCT adaptor, and the LHS the new etalon to SCT adaptor.
The IKEA knock down 90mm El Cheapo kit is shown:
   The customwood sections/ spacers
   90mm f10 Surplus Shed Objective
   110mm ERF combo
   front etalon adaptor
   PST etalon assembly
   rear etalon adaptor
   BF5 assembly from the PST

not shown is the SCT 2" focusser ( still to arrive!)
Just need to glue and screw, should be finished by the weekend.
I'll post more photos as it comes together.

[attachment deleted by admin]
C11, C9.25 SCT, 4" Genesis, NEQ6pro, modded 1000D,  ATik314L+, DMK41AF04, SM60DS/BF15, and Spectroscopes (many!).
http://tech.groups.yahoo.com/group/astronomical_spectroscopy/
"Astronomical Spectroscopy for Amateurs", "Grating Spectroscopes-How to Use them" -Springer

Offline NickH

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Re: El Cheapo 90mm Ha Solar telescope
« Reply #29 on: 10:10:38, 14 May, 2008 »
Nice...I like where this is going!

Celestron C11: DSI-C/Toucam Pro 2 ICX mod and SC1.5 mod/ Meade LPI/EOS300D/ED80/WO80ZS/Shoestring guider. PST/PST CaK/ART285

No time....always bloomin cloudy...need to build the Obsy..

 

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