just to make sure...

[vawnidge]

i wanna make a mylar filter to look at the sun (of course obvious safety rules apply) as there have been precious few starry nights lately, but i wanna put it on my reflector and i don't wanna blow it up is it gonna be safe or... just a piece of mylar on the end, will my secondary mirror still get too hot?

[astro_dt]

I think it's ok if you block the light and heat from entering the OTA

Plenty of places sell filters for SCT's which are closed tubes

No warranty on your scope though!

Danny

[Merlin66]

The Baader Mylar solar filter is 100% safe. - for both you and the telescope!

Just make sure of a couple of things

1. The filter is firmly attached to the end of the scope and can't accidentally fall or be blown off.

2. If the telescope is a truss design, use a black garbage bag taped around the trusses between the eyepiece and the main mirror. This prevents any accidental sunlight getting into the eyepiece holder while aligning on the Sun

3. Sit back and enjoy!! (Sunspot AR1010 is visible in white light).

[astro_dt]

One more thing, test the filter against a halogen bulg. You should be able to see enough light to make sure there are no leaks, holes or gaps.

Cheers

Danny

[philsail1]

"vawnidge"

May I just add (if anyone else hasn't already done so), if you have a finderscope on your telescope, I would advise either covering the object glass, or removing finderscope - just in case someone accidently looks through it when you have scope trained on the Sun.

Best wishes,

philsail1

[rusirius]

If you are using a solar filter then most of the light will be filtered out so overheating the secondary shouldn't normally be a problem. It might become a problem if you were using the projection method though and for this refractors are generally better suited. Its always best to consult the manual or the manufacturer to check whether scope is suited to solar observing and what additional precautions should be taken.

Another factor to consider is the size of the aperature. I don't think its advised to do solar observing with an aperature greater than 4 or 5in even with mylar filter. Beyond this the aperature needs to be reduced by partially obscuring the opening to the tube. On mine, the cover has a second cap that reduces the aperature to about 4in.

[FLO]

The Baader Mylar solar filter ...

Apologies for being pedantic but Baader AstroSolar Safety Film is not made from Mylar, though pretty-much everyone assumes it is. Baader use a purpose-made material that outperforms Mylar (which was never intended for solar observing) in every way.

HTH

[Talitha]

Another factor to consider is the size of the aperature. I don't think its advised to do solar observing with an aperature greater than 4 or 5in even with mylar filter. Beyond this the aperature needs to be reduced by partially obscuring the opening to the tube. On mine, the cover has a second cap that reduces the aperature to about 4in.

The glass solar filter for my 8"SCT is as large as the entire aperture and there hasn't been any internal OTA problems. I read that when you're doing lunar and planetary observing with a scope that has an aperture cap with a second 'removable' cap like yours, you're supposed to cap the scope and remove the second cap in order to stop down the aperture for brightness control.

[Merlin66]

I use full aperture glass solar filters on my 10" and 12" LX200.

The larger aperture gives better resolution; limited obviously by seeing conditions.

[rusirius]

Talitha, thanks for that info.

[Greg]

Have a read here...

http://www.mreclipse.com/Special/filters.html

and here..

http://www.skyandtelescope.com/observing/objects/sun/Solar_Filter_Safety.html

Only buy solar film or filters from a reputable source. And check thoroughly before each use especially when new as i've had two defective ones out of the box..Any sign of pin holing..Discard or return for replacement.

Any defects found, the filter must not be used..

SERIOUS EYE DAMAGE OR BLINDNESS WILL RESULT