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Vega comparison with various cameras

spectroscopy

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#1 Astrobodger

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Posted 22 July 2013 - 09:40 PM

Thought I'd try something back to basics while my Mammut CCD gets repaired/replaced or refunded. I dug out an old cheapo black + white security camera (ALDI I think) to see if it would be any good for spectra with a Star Analyser 100 (sa100)? I also had a cheap usb capture stick allowing me to record spectra as videos to my laptop.

 

The security camera chip is a tiny 1/4" so it took a while to align. Luckily the camera has a Toucam type thread so I had no issues mounting it to the telescope. The video capture control was just limited to brightness + contrast, but I managed to turn it down a bit to avoid saturation. The 30s of video was stacked in Registax6.

 

Below are Vega spectra taken (on different nights) using different setups, (including a DIY slit spectrometer), but all on the same 8" F5 newtonian telescope.

 

VegaVariousConfig.png

 

Conclusions?

 

  • The 300 l/mm slit spectrometer resolves lots of elements not visible on a slitless sa100 setup, (Ok that was obvious!).
  • QHY5 has the best UV response
  • The multiple lens elements, (of the 50mm + 135mm DSLR lenses) or the grating, in the 300 l/mm slit spectrometer seem to degrade the UV/blue sensitivity compared with slitless sa100 Mammut. (I might try just using a simple doublet as the colimator when I rebuild it).
  • When you consider the price (£10?), the security camera hasn't done that badly. The hydrogen balmer lines are clearly visible.

 

I am not suggesting you ditch your CCDs and go for a security camera (as there are other factors that come into play). What this does show is that that you can start spectroscopy with whatever you have to hand.

 

I want to try Vega with a Phillips 880 webcam next to see if the security cam beats the Phillips web cam because it doesn't have a bayer matrix? Place your bets now!

 

Thanks for looking

 

John

 


  • Neil likes this

Celestron 8" F5 Newt on EQ5

Spectrographs 300 l/mm & 1200 l/mm, SA100

Mammut L429, Canon 1000d, Canon 450d

 

http://uk.groups.yah...up/astrobodger/


#2 Neil

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Posted 23 July 2013 - 07:00 AM

Thanks John,

 

That a very interesting write up and comparison of the various options when starting out in Spectroscopy.

 

The Star Analyzer (SA100) does quite well, however, your homemade 300L/mm slit spectroscopy resolves more elements! I'm going to be in the USA for 3 weeks for my holidays soon and will be keeping an eye out for a grating and slit in one of there surplus shops, fingers crossed I'll find something.

 

Clear Skies

 

 

Neil.



#3 Astrobodger

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Posted 23 July 2013 - 05:53 PM

Thanks for that Neil.

 

Enjoy your trip to the states. Would be great if you could let me know what you find, I might be interested myself as I am always tinkering (when i get the chance).

 

cheers

John


Celestron 8" F5 Newt on EQ5

Spectrographs 300 l/mm & 1200 l/mm, SA100

Mammut L429, Canon 1000d, Canon 450d

 

http://uk.groups.yah...up/astrobodger/


#4 astrodoc71

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Posted 24 July 2013 - 11:33 PM

Security camera will certainly win because of what you mentioned- no bayer matrix  :)  

Regards

Dave


daveandtelescope.wordpress.com






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