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Add a Diffraction grating to Canon DSLR. Worth it?

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#1 Am33r

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Posted 06 August 2020 - 03:53 PM

Hi. I'd like to do simple Astronomy Spectroscopy and I have a Canon T6i with a canon 18-55mm lens, on a sturdy tripod.

Is it worthwhile to buy Star Analyzer 100 from https://www.rspec-as.../star-analyser/ and use it on my Camera?

The pic shows how the SA-100 is just added to the 18-55mm lens.

 

Are there free software options?

Because their software is $109 and the Annual Update is $24.

 

Or do I also need major magnification?

I do have an SCT telescope but I just thought I'd have the Spectroscopy independent from it.

I'd get it its own telescope if the DSLR is just a silly option.

 

Thank you for your advice


Edited by Am33r, 06 August 2020 - 04:01 PM.


#2 mwr

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Posted 07 August 2020 - 09:47 AM

 

Is it worthwhile to buy Star Analyzer 100 from https://www.rspec-as.../star-analyser/ and use it on my Camera?

The pic shows how the SA-100 is just added to the 18-55mm lens.

 

I would say that it is definitely worthwhile. A good point to start is consulting Robin Leadbeater's excellent web-page:  Simple Low Resolution Spectroscopy of Bright Stars Using a Digital SLR Camera (http://www.threehill...troscopy_11.htm) and Robin might chime in here and take over.

 

 

 

Are there free software options?

Because their software is $109 and the Annual Update is $24.

 

 

 

V-Spec by Valérie Desnoux would be an alternative to R-Spechttp://www.astrosurf.com/vdesnoux/

 

However, be aware, this program, while free, requires a steep learning curve and is not the best program for beginners. I bought a license for R-Spec and within a few minutes I was up and running with it. 

 

(Both programs are described in: Using Commercial Amateur Astronomical Spectrographs by Jeffrey Hopkins - a book which I can recommend for beginners)

 

 

 

 

 

Or do I also need major magnification?

I do have an SCT telescope but I just thought I'd have the Spectroscopy independent from it.

I'd get it its own telescope if the DSLR is just a silly option.

 

 

Using the Star Analyser in the converging beam of a SCT in a filter wheel gives you more light, a higher sensitivity and flexibility. So it's not necessary to get its own telescope (that's one of the reasons why the Hubble Space Telescope is equipped with a grism. See also Robin's web-page for more information on the Star Analyser in the converging beam setup:

http://www.threehill...pectroscopy.htm

 

And finally a warning: You can get easily addicted to spectroscopy ....


Edited by mwr, 07 August 2020 - 11:26 AM.

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#3 Am33r

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Posted 07 August 2020 - 02:55 PM

I would say that it is definitely worthwhile. A good point to start is consulting Robin Leadbeater's excellent web-page:  Simple Low Resolution Spectroscopy of Bright Stars Using a Digital SLR Camera (http://www.threehill...troscopy_11.htm) and Robin might chime in here and take over.

 

V-Spec by Valérie Desnoux would be an alternative to R-Spechttp://www.astrosurf.com/vdesnoux/ However, be aware, this program, while free, requires a steep learning curve and is not the best program for beginners. I bought a license for R-Spec and within a few minutes I was up and running with it. 

 

(Both programs are described in: Using Commercial Amateur Astronomical Spectrographs by Jeffrey Hopkins - a book which I can recommend for beginners)

 

Using the Star Analyser in the converging beam of a SCT in a filter wheel gives you more light, a higher sensitivity and flexibility. So it's not necessary to get its own telescope (that's one of the reasons why the Hubble Space Telescope is equipped with a grism. See also Robin's web-page for more information on the Star Analyser in the converging beam setup: http://www.threehill...pectroscopy.htm

 

And finally a warning: You can get easily addicted to spectroscopy .

Thank you for going out of your way to help me (=


Edited by Am33r, 07 August 2020 - 07:16 PM.


#4 robin_astro

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Posted 10 August 2020 - 10:13 AM

Hi. I'd like to do simple Astronomy Spectroscopy and I have a Canon T6i with a canon 18-55mm lens, on a sturdy tripod.

Is it worthwhile to buy Star Analyzer 100 

The Star Analyser in front of a DSLR is good for bright objects and can give higher resolution than when used between telescope and camera. It is also good for extended objects. (To get good slitless spectra the target has to appear almost "star-like" in the field of view) See Torsten Hansen's Comet NEOWISE here on the RSpec forum for example.

https://groups.io/g/...my/message/8075

 

Although it is possible to use a fixed tripod (arranging so the stars trail vertically relative to the spectrum) I would suggest using the camera  on a tracking mount eg piggybacked on the main scope as this would concentrate the light in the spectrum allowing you to go fainter. If using the stock 18-55mm lens I would recommend the SA200 over the SA100 as this would give a longer spectrum and therefore higher resolution. See here on my website for a comparison for this application. 

http://www.threehill...troscopy_17.htm

 

You can go much fainter though with the Star Analyser mounted between camera and telescope. Have a look at Christian Buil's page here for some examples of how to use it with a DSLR and telescope. (Don't worry about the added prism you don't need that, to start with at least) 

http://www.astrosurf...nalyser/obs.htm

(note that his DSLR is modified with the UV/IR cut filter removed so has a wider response)

 

Cheers

Robin


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