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Use of vintage eyepiece sun filters.

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230 replies to this topic

#226 Joe Cepleur

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Posted 07 April 2016 - 10:22 AM

Sun filters were expected to be used with Huygenian eyepieces where the focal plane is actually inside the eyepiece and so the filter is far from it and probably not subject to great heat concentration.


In theory, perhaps, and an interesting point; yet, in the history of broken Sun filters, surely many broke while used with the Huygens sold with many classic telescopes. Using an eyepiece filter with a Huygens eyepiece places the filter within an inch or two of the most concentrated rays, exposing it to far more heat than, for example, a perfectly safe filter over the objective. One hopes readers would not misinterpret this as meaning it were okay to try using an aging eyepiece Sun filter with a Huygens eyepiece. Don't do it. Not worth the risk! 

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#227 Mr Magoo

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Posted 04 May 2016 - 06:02 PM

Not for the squeamish maybe, but the proof is in the seeing so to speak. http://www.scienceal...ugh-a-telescope

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#228 Rich (RLTYS)

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Posted 05 May 2016 - 05:36 AM

Most interesting but absolutely true.


Rich (RLTYS)

#229 saemark30



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Posted 29 July 2016 - 09:53 AM

Does anyone have a sun filter of 1.25" size they can donate for a experiment?

#230 twhite



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Posted 07 October 2016 - 03:57 PM

How does one use these old screw in sun filters with a Hershel wedge? Seems to me the Sun's image would be too dim afterwards.  :confused:

As an experiment, I tried this while at OTSP this year with a classic Herschel Wedge in the same 60mm f/7 scope I have set up side-by-side with my 60mm Coronado.  It uses the same 36.4mm threaded visual backs that Vixen does, and I happen to have a 24mm visual back, so -- let's see what happens!


Yes, this image is *far* too dim afterwards.  I had hoped it would not be so that I could use my classic scopes for solar as well, but sadly, that won't be the case.


The filters that I have a very, very dark indeed -- too dark, in fact.  I know I've seen lighter filters -- and some that have a more greenish tint to them -- so I may have to try one of those next, should I lay hands on one again.  I do have one of the Unitron-branded wedges and filters, but I'm not a fan of that setup.


So I guess I'll stick to using my 1.25" Lunt, even though I have to use an additional ND filter with it.  Better safe than sorry!

#231 Ken Watts

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Posted 11 January 2017 - 09:56 AM

I have a lightning bolt shaped scar on my retina from the mid 1970's when my filter cracked.  Was on a 6" f/8 newt on about the 20th time looking at sunspots.  DON'T play roulette with your vision!  Technology has come too far to use the old eyepiece filters.

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