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White light filter as an ERF

Posted: Tue Feb 03, 2015 3:49 pm
by Starry Jack
While I wait for the funds for a proper ERF for a 100mm f10 achromat PST stage 1 mod project, I want to use a white light filter as the ERF. What kind of image will that provide?

Thanks,
Jack

Re: White light filter as an ERF

Posted: Tue Feb 03, 2015 8:02 pm
by marktownley
Welcome to the forum!

You won't get a Ha image this way, it will cut too much light.

Re: White light filter as an ERF

Posted: Tue Feb 03, 2015 9:04 pm
by Starry Jack
Thanks. How about welders glass combined with a UV IR cut Filter?

Re: White light filter as an ERF

Posted: Tue Feb 03, 2015 10:14 pm
by marktownley
Nope, fraid not. Welders glass is incredibly poor optically and would also cut the light too much.

Re: White light filter as an ERF

Posted: Tue Feb 03, 2015 11:26 pm
by Starry Jack
Fair enough. What is the most cost effective ERF source you know of for a sub-objective ERF considering I am willing to make it internal and smaller than the objective.

Can't swing $800 for a 100mm objective ERF.

Best,
Jack

Re: White light filter as an ERF

Posted: Wed Feb 04, 2015 3:50 am
by Merlin66

Re: White light filter as an ERF

Posted: Wed Feb 04, 2015 5:19 am
by swisswalter
Hi Jack

welcome to that wonderful site. Have fun in the sun.

Sometimes you can find the ERFs used on this site, on astromart, U.K. Astronomy Buy&Sell or astronomie.de

Re: White light filter as an ERF

Posted: Fri Feb 06, 2015 2:27 am
by Starry Jack
Neo,
Thank you for the internal ERF description. That is indeed encouraging.

Starry Jack