American Association of Variable Star Observers (AAVSO)
Sun, 02/26/2023 - 10:06

Hi, I have a Mak127/1500 Skywatcher with full aperture filter in Astrosolar (Baader) which I constantly check for holes! I wanted to know if there is a quality glass filter comparable to the Astrosolar for my telescope, in order to be more relaxed in my observations.



Glass solar filter

Baader Solar film provides the highest quality image of the solar filter films and higher quality than the glass filters.  Optically flat glass is very expensive.  I’m not aware of any of the glass filters that use it.  Yes, you should check any filter, film or glass before use.  It’s a simple check.  And yes the coatings of glass filters deteriorate with age.  

American Association of Variable Star Observers (AAVSO)
glass filters

Hello. Could you please comment on the criteria used to affirm that Baader film is of better quality than glass filters, such as Seymour or Meade (I think they are the same). Thank you

glass or mylar?

Hi Victor,

Looks like Seymour filters are mylar film.  Not sure of your question about glass?  Here's another supplier of mylar filters:

I like the LUNT tilt etalon filters, although they are expensive.

Which is better I can't say.  



American Association of Variable Star Observers (AAVSO)
Thanks to everyone for thinking safety first!

Maurizio and Mike -


Thanks for the important reminder to always check your filter for holes/cracks, etc. It should be a two parter - looking directly at your filter away from the sun to look for obvious defects, and then holding the filter up towards the sun using just your eye and looking for bright spots. The same process should be used for checking eclipse glasses.



glass solar filter

try one more filter in the eyepiece.....

works for me


safety - never remove your full ap  filter already in place...

Royal Astronomical Society of Canada (RASC)
glass solar filter

Hi Maurizio

I have both filters. The Mylar is good for a white/blue Sun which gives a bit more contrast on the Groups. Of course care must be taken with the Mylar, as it can tear, rip and get pin holes, then it needs to be replaced. This I use on my 8" Dob, which is cut down to a smaller apeture Solar Filter.

The Glass filters, tend to give the Yellow Sun that we know if that is what you are looking for. If the #58 Green Wratten filter is used with  your eyepiece and filter, it will give the blue/white colour to the Sun. Small points of pin holes can show up on the glass filters as well, so always hold up to the Sun first then look to inspect the intactness of your filter.

I used the Glass filter on my Telescope but it was replaced by Solarlite Polymer. This gives the Sun the orange /yellow colour. Another site is

Both filters are good, it just depends on what you are looking for.

Kim Hay



American Association of Variable Star Observers (AAVSO)
solar filters

Hi Maurizio,

On my 4" F/10 Newtonian I've found that I prefer the Thousand Oaks, full aperture, Solarlite filter.

In the past, I've tried the Baader filter, and it is a very good filter, but at 62X (the magnification I use for Sunspot counting) found the image produced by the Baader filter to be uncomfortably bright. 

Steve T.