Original Coronado/ IOM 50mm etalon/ blocker

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Merlin66
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Original Coronado/ IOM 50mm etalon/ blocker

Post by Merlin66 » Thu Oct 20, 2016 9:32 pm

Does anyone have first hand experience with the old original IOM filters?
I have a 50mm etalon with ERF and the associated blocking filter diagonal.
I've quickly set them up on the ED80 without success.....
No visible surface details..
I'll set the etalon and then the blocking filter on the spectroscope to evaluate, but if someone has a similar set-up working, I'd love to hear from you.
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Bob Yoesle
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Re: Original Coronado/ IOM 50mm etalon/ blocker

Post by Bob Yoesle » Fri Oct 21, 2016 2:50 am

The blocking filter may have shifted with age:

http://www.cloudynights.com/topic/45662 ... try5933149

Do you have available a newer known - good Coronado BF? This would provide perhaps a quick answer...
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Merlin66
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Re: Original Coronado/ IOM 50mm etalon/ blocker

Post by Merlin66 » Fri Oct 21, 2016 3:22 am

Bob,
Thanks.
The blocking diagonal only has one optical element - the internal filter on the tilt plate.
This filter seems to be a combo of an ITF reflection (white glass) bonded to a green glass element (KG3?)
There's not the usual ITF IR filter up front...
Yes, I've tried the etalon with both a Lunt BF1800 and a Coronado BF15 - no surface detail....
"Astronomical Spectroscopy - The Final Frontier" - to boldly go where few amateurs have gone before
https://groups.yahoo.com/neo/groups/ast ... scopy/info
"Astronomical Spectroscopy for Amateurs" and
"Imaging Sunlight - using a digital spectroheliograph" - Springer

george9
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Re: Original Coronado/ IOM 50mm etalon/ blocker

Post by george9 » Fri Oct 21, 2016 1:03 pm

I know of several 2000-2005 Coronado filters that have de-contacted with any known fall or bump. That may be the case here. For mine, I hacksawed the case open (it was glued shut during that period), confirmed that the spacers hadn't fallen off (they were still stuck on one side), re-contacted it (literally just push it back together), and it worked fine. Other than having to figure out what to do with the casing now. I had sawed it so that there was still some thread left and exploited that.

George

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Re: Original Coronado/ IOM 50mm etalon/ blocker

Post by Merlin66 » Fri Oct 21, 2016 10:39 pm

George,
Thanks for that... but maybe a bit drastic at this stage.
A sticker on the original box indicates 1999.....
Hopefully the rain and wind will ease enough to do a spectroscope check.
"Astronomical Spectroscopy - The Final Frontier" - to boldly go where few amateurs have gone before
https://groups.yahoo.com/neo/groups/ast ... scopy/info
"Astronomical Spectroscopy for Amateurs" and
"Imaging Sunlight - using a digital spectroheliograph" - Springer

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