Just for the record, Al Nagler has stated that there is no problem using their NP scopes for solar viewing with a wedge. The rear elements are far enough forward in the light path that there is no heating problem. I can't comment on others such as those from Takahashi.

 

Don Anderson

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From: "'Woody Schlom' woody@... [ap-gto]"
To: ap-gto@...
Sent: Wednesday, April 6, 2016 3:13 PM
Subject: RE: [ap-gto] Re: solar filters

 

Pawel,

I'm curious about your comment to keep the Sun centered to prevent heating up the telescope elements.  Unless you've got a 4-element Petzvel design scope where the rear elements are near focus, I don't see two or three elements at the front of the scope where the image is totally unfocused, heating up -- whether centered or not.

 

I'll admit that my little 80mm triplet doesn't transmit nearly as much light and heat as your big aperture scopes, but I've never heated mine up to the point where the wedge was uncomfortable to touch -- even while imaging continuously for 7 hours with an ambient temperature of 98° F. 

 

And I sure don't understand why keeping the sun centered would decrease heat buildup in the telescope lenses.

 

Woody

 

 

 

Mike

Definitively the wedge. I have been using it on my AP152 and the views were terrific and I had no issue getting info focus with Canon. Views are better than baader Astrosolar. But if you just want to try, get the filer foil and make yourself a safe filter cell. Costs close to nothing compared to the scope.

One point with wedge - keep the sun centered, otherwise it will heat the telescope elements. You may need to cover the scope from time to time to let the heat trap cool. Just follow the instructions. It is very safe.

CS

Pawel Lancucki