Testing a little objective prism

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Testing a little objective prism

Postby Paolo Berardi » Wed Jul 22, 2015 11:04 pm

Not tonight but some days ago... During a star party which took place in Gran Sasso mountain I brought a lightweight portable setup consisting of a small refractor with a little 3 degree prism placed in front of the lens.

This was just a test that will let me know the results with such a tool. The diameter of prism is only 2 inch (you can see it on the Pentax 75)

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Working...

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Some celestial objects observed on 17 july 2015 (from 21 to 23 UT):

Messier 57 Ring nebula, 120 sec exposure:

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Wolf-Rayet 136, 30 sec exposure:

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Nova Oph 2015, 20 mins exposure:

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Nova Sgr 2015 #2, 20 mins exposure:

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Just for fun! Perhaps useful for any surveys? Maybe with a larger prism diameter...

Paolo
Paolo Berardi
 
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Re: Testing a little objective prism

Postby Robin Leadbeater » Sun Jul 26, 2015 2:25 pm

Nice Paolo :-)

Mike Harlow has also been experimenting with a 100mm diameter 12 deg objective prism belonging to the BAA and getting some nice results, here for example
https://britastro.org/node/6551
http://forum.oasi.org.uk/download/file. ... &mode=view

Robin
LHIRES III #29 ATIK314 ALPY 600/200 ATIK428 Star Analyser 100/200 C11 EQ6
http://www.threehillsobservatory.co.uk
Robin Leadbeater
 
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Re: Testing a little objective prism

Postby Paolo Berardi » Mon Jul 27, 2015 10:07 pm

Thank you Robin! Obtained with a large prism and a long focal length, they are very nice 2d spectra. The "stretched" blue part of spectra for the non-linear dispersion is captivating... We're used to see a "crowded" world in the UV region!

Paolo
Paolo Berardi
 
Posts: 578
Joined: Thu Sep 29, 2011 10:51 pm

Re: Testing a little objective prism

Postby Robin Leadbeater » Tue Jul 28, 2015 7:31 pm

Yes indeed. In "the old days" prisms and blue sensitive films must have made a perfect match !

Robin
LHIRES III #29 ATIK314 ALPY 600/200 ATIK428 Star Analyser 100/200 C11 EQ6
http://www.threehillsobservatory.co.uk
Robin Leadbeater
 
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