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Solar Glass

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#1 Mr Magoo

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Posted 07 April 2007 - 12:10 PM

I have read that some of these vintage scopes came with a "Solar Glass". What exactly was this? I have also seen that it is not recommended to use these. Why?

#2 Don W

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Posted 07 April 2007 - 12:38 PM

It was a filter screwed into the eyepiece. When you adjust the focuser you can run the filter through the point of focus which can heat up the filter and cause it to crack. Not a good thing.

#3 BHunt

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Posted 07 April 2007 - 01:53 PM

Wow Don didnt know that. Thanks for the info. Learn something ever day in here.
Bill

#4 Jae

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Posted 07 April 2007 - 01:59 PM

Don,

As a kid I tried using the solar filter in my Tasco 9TE-5 but never could see anything through it but to show you how hot it can get, the plastic baffles in the focuser melted in the process.

So I was fortunate I couldn't see anything or something worse could have happened.

Jae

#5 refractory

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Posted 07 April 2007 - 02:24 PM

My younger brother was temporarily blinded by a solar ep filter which cracked suddenly while he was observing with my 4.5inch reflector about 35 years ago. Not good news since he was already blind in the other eye. So as you can imagine he wasn't too thrilled when I wanted to show the sun to his kids last year- had to convince him that a front-mounted filter was an entirely different animal.

All these ep sun filters should be destroyed or encased in lucite if you must have it around.

Jess Tauber

#6 BHunt

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Posted 07 April 2007 - 03:26 PM

I just opened my Selsi Unitron to work on it. I noticed that the sun filter with this unit is a cap that goes over the external part of the eyepiece.Wonder if that type of a setup proved safe?
Bill

#7 Nebb Ular

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Posted 07 April 2007 - 05:41 PM

I am not an expert on solar observing and I am not sure what kind of solar filter you mean. The ones I have seen for eyepieces thread into the bottom of the eyepiece and are subject to heat breakage. It would be the same I think whatever end of the eyepiece is used to attach the filter. I believe the safe way is to filter the sun before the objective gets the light. That way nothing dangerous is entering the telescope to begin with and there is no worry about something melting or breaking. I would think that some refractor objectives would be harmed by the heat without a filter as well. Someone let me know if I am wrong about that. Just make sure the filter is secure over the main telescope tube. I have one that I have to add a bit of tape to because it is just barely too large for my refractor. Hmmmm, memories....I remember using that sun filter when I was a kid. I was fortunate it did not
break, :foreheadslap: Ken

#8 Awesomelenny

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Posted 07 April 2007 - 05:52 PM

Hello all!

HERSCHEL WEDGE!!!

These glass filter are ok to use providing you use a Herschel Wedge (looks like a star diagonal) before the eyepiece. It displaces the heat energy out toward the back end of the wedge.

The safest is using the modern solar filters that you place on the front of the objective.

One thing for sure... Before you do any solar viewing ... read up on safe methods of solar viewing.

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  • 1530431-wedge.jpg


#9 BHunt

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Posted 07 April 2007 - 06:21 PM

Gee that looks like another Unitron accessory!
Bill

#10 Mr Magoo

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Posted 07 April 2007 - 06:38 PM

I believe that the Sears scope I just bought yesterday, but do not have in my possesion, has such a filter. If you look at the photos in the auction, it shows 2 filters still in their packages, Sun Filter and Moon Filter. I have also seen that some of the older scopes have some sort of projection screen with them for solar viewing. Did these use any kind of filter? I would think that the sunlight going directly through the optics wouldn't be good for them. I have considered getting a modern glass filter for my Sears if I can find one of the right diameter to fit the tube.

#11 Mr Magoo

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Posted 07 April 2007 - 06:39 PM

I have ATM plans for building a solar scope using these wedges. Are these a vintage item or still available?

#12 BHunt

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Posted 07 April 2007 - 06:47 PM

Here is one you can bid on Ken.
http://tinyurl.com/23pq7l
Bill

#13 Bonco

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Posted 07 April 2007 - 06:58 PM

Thousand Oaks filters is the best place to obtain white light objective lens solar filters. They offer many sizes to fit almost anything. A bit pricey but perfectly safe. The sun is a natural yellow rather than blue like other filters. I highly recommend them.
Bonco

#14 Glassthrower

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Posted 08 April 2007 - 09:37 PM

Call me crazy, but even with a glass or mylar filter in front of the objective, after a long session of solar viewing, I could *swear* my eyes felt dried out....if that makes any sense. My eyes did feel funny after I did solar viewing - every time I tried it which was three times with a glass filter and 2 or 3 times with a mylar. No harm or permanent damage, but something just didn't feel right. My eyes have never felt dried-out and sandpapery like that after a marathon *night* observing session. So, I got a wee-bit paranoid and sold off all my solar filters. And I swore off solar viewing.

Then I had a look through a friend's Ha PST. Wow. Prominences are pretty darn cool. And you know what? My eyes didn't feel funny afterwards.

Am I just being crazy?

Regards,

MikeG

#15 mikey cee

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Posted 08 April 2007 - 10:30 PM

Never use cemented eyepieces always use the SR(special ramsden types) when using your projection screens with your vintage refractors. No H(huygenians) or HM(huygenenian mittenzways) they have a cemented element involved. MIke

#16 dfell

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Posted 08 April 2007 - 11:10 PM

Modern Herschel wedges are available from Baader (Alpine Astro) in both 1 1/4" and 2" format with filters included. For my classic 3" f/15 Towa, I simply bought a Kendrick filter to fit the works the best, even though I have a Thousand Oaks filter for my TV102, if you buy the photographic Kendrick (ND3.9) you can also use a solar continuum filter with the 3" and bigger scopes for enhanced white light views. the solar projection method works well for groups but the scope must be supervised to prevent someone from turning the diagonal and looking through the eyepiece!

#17 Don W

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Posted 09 April 2007 - 06:17 AM

Do not use any filter that screws onto the end of the eyepiece or covers the eye lense. Either one can be subjected to incredible heat and crack or even burst.

#18 Mr Magoo

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Posted 09 April 2007 - 10:45 AM

Thanks for all the info. I really appreciate it. I might have tried out the filter had you all not enlightened me and saved me.


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