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Merlin66

Spectroscopy -Why no takers??

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Acey,

I cut a suitable hole in the sides of a plastic film container to hold the prism at the minimum deviation angle (around 30 degrees) relative to the exit pupil of the eyepiece. I just place the plastic "cap" over the end of the eyepiece and look into the "gap" to see the prism at the correct angle. This is very effective both on planetaries and other emission nebula.

I can take a photo of the set-up if it would help.

Ken

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I can take a photo of the set-up if it would help.

Ken

yes, please ;-)

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Yes, I'd like to see a photo too - this sounds very interesting. I'm assuming the film cannister slides over the eyepiece with eyecup removed. And the prism is held in place with something like tape? Do you need a small hole or slit in the cannister to set the view at the correct angle?

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I'll post a couple of images later today.

I cut a triangular hole in two sides of the canister ( which hold and locate the prism) and a "viewing port" at 90 degrees; the open end just "sits" (by hand) over the end of the eyepiece and you look into the "viewing port" to see the spectrum.

When you see the images you'll better understand the concept.

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OK here are some images. I didn't realise it was first built in 1978!!

The added black card and diaphragm was to improved the alignment and make it easier to use. Not mandatory.

The open end of the original cassette just rests on the eyepiece.

Any questions just ask.

post-15261-133877518205_thumb.jpg

post-15261-133877518211_thumb.jpg

post-15261-133877518216_thumb.jpg

post-15261-133877518223_thumb.jpg

post-15261-133877518228_thumb.jpg

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Thanks for those images - I shall have to give it a try. Nice to see some vintage equipment still in use!

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Thank you John & Macavity your advise. I think one of my major hurdles is that I don't have a telescope....now, that's a problem....unless I find robotic sites which offer spectroscopy at reasonable price....

But, are there any pictures of a typical (minimal) set up I could look at?

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Do you have a DSLR camera with some standard lenses and a solid camera tripod?

You may be able to do some "objective grating" spectral imaging;

this is when a grating is placed directly infront of the camera lens and as long an exposure as possible is taken of the night sky - the target star(s) being jus inside the FOV.

I'm not aware of any remote telescopes offering to collect spectral data but it's an interesting idea.

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Do you have a DSLR camera with some standard lenses and a solid camera tripod?

...

No I don't have a DSLR camera at the moment. Mmm...that would be very portable indeed and looking at the images you posted there's not a lot needed...good :) , ok...I'll think about it... cheers! :)

Edited by Rosanella

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Jack,

Welcome to the forum!

You'll find there's a growing interest in Spectroscopy and hopefully we can assist these newbies!

The book was with the printers before Xmas.......

ken

(BTW Jack Martin has published an Atlas of Bright Star Spectra - he used a Rainbow Optics grating and B&W film - very usefull to the beginner)

A Spectroscopic Atlas of Bright ... - Google Books

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Hi Ken , Publication looks to have slipped back to April 1 st 2011. I have it on order from last year . See this from my Amazon email :- Hello, Unfortunately, the release date for the item(s) listed below was changed by the supplier, and we need to provide you with a new estimated delivery date based on the new release date:

Ken M. Harrison "Astronomical Spectroscopy for Amateurs: How to Build and Use Spectroscopes (Patrick Moore's Practical Astronomy Series)"

Estimated arrival date: April 01 2011

One of Amazon's aims is to provide a convenient and efficient service; in this case, we have fallen short. Please accept our sincere apologies.

Looking forward to it when it is finally out :D

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Hmmm

I'm trying to get confirmation of publication date(s) from Springer.

The manuscript was submitted on the 3rd March 2010.

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Met with John today to pick up a copy of Stellar Spectral Classification and a peek thru his rating at the suns spectra. Very interesting and I've learnt a lot already. Nice to meet John as well who was very kind with his time and very knowledgeable

was hoping to get out tonight, but no luck yet! Hopefully in a bit if it stays clear.

I've not had any notification of delay in Ken's book, so hopefully just a glitch!

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Hi Ken & All , Checked on Springer's site too re publication date Search results | Springer and find 31 st March 2011 . It will be well worth the wait (but I would have loved it for Christmas !) .

I have Jack's book (bought as soon as I knew it existed) as I have seen his spectra photographs over many years . They used to show up in the astro club displays at the Astrofest .

I have a book on order re the Arduino (published by Apress ) whose publication date has slipped by 12 months !

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Hi "The Thing",

Did you manage to get any spectra of rigel last night it was clear here in Kingston initially but turned foggy after a couple of hours

cheers

John

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Hi John,

Not yet! By the time I'd got set up and aligned a mixture of cloud and mist had rolled in, which just got thicker and thicker! :D

try again next clear night...

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... just wandering... is anyone using a digital camcorder for spectral analysis?

The reason I'm asking is because I've been thinking of getting a digital camcorder (under £200 range) for music stuff I do, and if I could use the same camcorder for spectroscopy then I won't need extra equipment apart from the lens and some software).

... any thoughts..... :)

P.S. Since I'll be going to Astrofest, I'm getting as much info as possible before I dig a hole in the credit card.... or should I leave it home? :)

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P.S. Since I'll be going to Astrofest, I'm getting as much info as possible before I dig a hole in the credit card.... or should I leave it home? :)

You either take it and live with the debt for years, or leave it at home and live with the regret for years ... :)

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Rosanella,

Interesting thought... a Star Analyser grating on the front of a camcorder lens...

A couple of things come to mind:

The pixel size and resolution of the CCD in the camcorder ( any info available?)

The focal length of the lens - I'd assume this may be short so the final spectrum length would also be pretty short.

Can the video file be saved as an AVI for processing through Registax?

Tom Field's Rspec can handle live view....maybe also a camcorder...

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Looking at spectra posted taken with the Star Analyser, and at the PH website, it is clear that the resolution achieved is rather poor (5 to 10 nm quoted I seem to remember). Is there any way of achieving much better resolution than this with a fairly simple system, as I want to have a bash at looking at the line profile of H alpha itself, which will need resolution of 0.1 nm or better I imagine??

Chris

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Short answer: No

Longer answer: You need a slit/ collimator/ grating/ imaging camera spectroscope to get the sort of resolution you're looking for.

You can build your own spectroscope....there's details on the Y! astronomical_spectroscopy group or you can buy a commercial unit like the Shelyak Lhires III, or the SBIG SGS.

The spreadsheet SimSpec V3 allows you to design a suitable spectroscope....

simspecV3.2c.zip

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