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aa6ww
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Reged: 10/23/11

Loc: Sacramento, Calif.
Is there a contras enhancing H-alpha filters new
      #5532547 - 11/21/12 03:58 PM

One of my fun past times is H-alpha solar astronomy. I have a Coronado Solarmax 90 filter with a BF-15 Ive been enjoying for a while, using it on a variety of scopes from my TSA-102, Celestron Omni-150 F/5 and TOA-130. My favorite eyepieces are the Coronado CEMax eyepieces because of the Contras Enhancing feature which keeps the sky background black, vs a reddish glow when using other types of eyepieces.
Recently I picked up a Denkmeier Binoviewer and was amazed at the difference a binoviewer can make for solar astronomy. Currently I have just one set of the CEMax eyepieces.

My question is, has anyone ever experimented with Eyepiece filters which will do the same job the CEMax eyepeieces do, which is darken the back ground skies when solar view, vs having the views showing a reddish glow around the sun when using non CEMax eyepieces?

This question is coming up now, because Ive become interested in the Denkmeier 21 and 14mm eyepieces vs picking up a pair of 24mm Pan Optics and maybe a 19mm set of Pan Optics, Maybe more sets of different eyepieces down the line later on also.

So, does anyone know of an eyepiece filter which does the same thing as the CEMax eyepieces do? Any real time experiences without assuming something does or doesn't work?

Thanks for any advice or knowledge on this subject.

...Ralph in Sacramento


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highfnum
Carpal Tunnel
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Reged: 09/06/06

Loc: NE USA
Re: Is there a contras enhancing H-alpha filters new [Re: aa6ww]
      #5532569 - 11/21/12 04:12 PM

i use a 1nm(10A) h-alpha filter to darken background
but be prepared to pay 200 dollars


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Doug D.
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Re: Is there a contras enhancing H-alpha filters new [Re: highfnum]
      #5533343 - 11/22/12 03:40 AM

I never felt that the CEMAX eps offered anything particularly special over other decent Plossls and other relatively simple designs. I've tried quite a few eps with my TV76/SF70 rig and up there with my all time favorites would be the Tak LE's (i.e., 12.5 and 18mm). I had 2 sets of CEMAX for binoviewing and sold them to help fund 2 pairs of the LE's.

I agree that getting a view of Sol in h-alpha against an inky black sky is the way to go and I'd recommend trying all sorts of eps you might have lying around or that you can borrow - you may well be surprised by the results. A case in point are a pair of Zeiss microscope eps I've been playing with lately.

By the way, in my scope and binoviewers (Baader Maxbright and MarkV) at least, the Pan 24s work surprisingly well for h-alpha and I can recommend them. I've yet to find an ep filter that noticeably improves h-alpha contrast but I haven't done a systematic survey.


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CarlDD
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Reged: 07/23/07

Loc: Haiti at the moment
Re: Is there a contras enhancing H-alpha filters new [Re: Doug D.]
      #5533375 - 11/22/12 05:03 AM

Hi Ralph
I have an SM90 abd BF10 and Denk standard with Power Switch, used on my TV101 and various pairs of eyepieces.

If I have a clear blue sky then I have a clear H-Alpha sun on a black background. In my experience it's not the scope or eyepiece combination, only the sky.

This must be an example of YMMV.

Best Regards

Carl


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mhilscher
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Reged: 07/13/11

Loc: Cologne, Germany
Re: Is there a contras enhancing H-alpha filters new [Re: CarlDD]
      #5533861 - 11/22/12 12:22 PM

Greetings Ralph,

You may look at this item:

http://en.beloptik.de/h_alpha_filter_x1_5a.html

Matthew web page


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aa6ww
professor emeritus
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Reged: 10/23/11

Loc: Sacramento, Calif.
Re: Is there a contras enhancing H-alpha filters new [Re: mhilscher]
      #5534802 - 11/23/12 03:04 AM

Thanks for your responces everyone. Starting tomorrow, I will be having some clear blue skies so I'm gonna try every combination of eyepiece and filter I have, including color filters and see what happens. Ive also been told a MV filter works so that should be interesting. I'll report back any successes I have. Thanks again!!

...Ralph in Sacramento


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highfnum
Carpal Tunnel
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Reged: 09/06/06

Loc: NE USA
Re: Is there a contras enhancing H-alpha filters [Re: aa6ww]
      #5534925 - 11/23/12 06:53 AM

Try a light blue filter
For. Simple disk. Enhancement


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Pentax Syntax
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Reged: 11/03/12

Loc: Maryland
Re: Is there a contras enhancing H-alpha filters new [Re: highfnum]
      #5590901 - 12/27/12 09:54 AM

I would have to second Doug D.'s views about the Takahashi LE eyepieces in the PST. They win out over the CEMAX eyepieces for overall contrast and eye relief.
One other means of optimizing contrast is using a variable polarizer on the eye lens side of the eyepiece. I use a .965" variable polarizer and just twist to get maximum contrast. Of course, good eye relief is required for this to work well. The polarizer approach is particularly useful if you can shroud yourself from stray light with an observing hood or cloth.


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BYoesle
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Loc: Goldendale, Washington USA
Re: Is there a contras enhancing H-alpha filters new [Re: Pentax Syntax]
      #5591295 - 12/27/12 02:53 PM

Yes - a second SM90 filter will dramtically improve contrast and decrease background scatter.

If the image is too bright, and therefore oversaturating the retina - use a polarizer, ND filter, or even Ray-Ban's to decrease the brightness.

Stray light from around the eyepiece can be shielded by hoods or eyegards, and also greatly helps with contrast.

Eyepiece coatings - although I have not found these to be significant as the first three choices. You may also want to check out the solar H alpha optimized eyepieces from Lunt: http://luntsolarsystems.com/blog/lunt-eyepieces

Lastly, I have not tried them, but would postulate that very narrow 7 nm H alpha nightime filters would possibly be of benefit...


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