Testing a Bader Solar Filter

[RichM63]

I need a spot of reassurance/advice.

I have a Bader Solar Filter for the ST80 but I've always been too scared to use it. Effectively I only have one working eye, so you can understand my hesitation.

However with the Transit in early May I quite fancy having a go and hooking up the ST80 with either an EP or DSLR or maybe modded LifeCam.

But, is there a safe way to check the integrity of the filter before using it.

Visibly it looks OK, no cuts, holes etc...

Cheers, Rich

[Alien 13]

I would go with the webcam the image scale should be quite good I would think you ideally want to get Mercury as a disk rather than a point of light (or dark in this case).

Alan

[Psychobilly]

I always carry out an initial visual inspection for damage if it looks OK I then  look  through the filter at arms length passing the unmagnified solar disc image across the full surface  of the disc looking for any changes in brightness or break through

I had a hailstone put a dent in the front of the Kendrik Solar film Filter  for the 600/f4 on Saturday   There's no difference in intensity but...

Peter...

 

 

[niallk]

35 minutes ago, PBS said:

I always carry out an initial visual inspection for damage if it looks OK I then  look  through the filter at arms length passing the unmagnified solar disc image across the full surface  of the disc looking for any changes in brightness or break through

I had a hailstone put a dent in the front of the Kendrik Solar film Filter  for the 600/f4 on Saturday   There's no difference in intensity but...

Peter...

 

 

This is also what I do, and I also make absolutely certain that the filter will not be dislodged from the scope by accident in use.  I know what you mean though: I definitely was nervous using it the first time.  I held the palm of my hand over the focusser draw tube with no EP in place looking for any obvious intense light ... not very scientific!  FWIW, I have been very pleased with what the solar film hase shown me

[Joe12345]

You could always try putting a phone up to the eyepiece before your eye, or holding a piece of paper in front of it and see if anything is projected on it. That's probably what I would do.

[Dave In Vermont]

I'll hold mine up in roomlight and shine a bright flashlight/torch in front of it while looking for any sign of light from the rear I'm looking at. Once in awhile I'll use a high-powered green laser. But that's overkill really. But I enjoy playing with my toys now & again!

Dave

[Psychobilly]

The method I suggested is as per the instructions provided with the film...

I tend not to have any other convenient light source with me when I am out in the field in daylight with the scopes...

As with all things Solar .. If in doubt don't...

http://astrosolar.com/en/download/how-to-handle-baader-astrosolar-with-safety-instructions/

And for those who don't follow the link to the PDF...

The relevant section on "testing"

5. Before each solar session carefully inspect your AstroSolarTM filter for mechanical dam ages, broad scratches,

streaks, extensive whipe marks and other quality degrading influences. Small pinholes do not degrade the eye safety

or image sharpness of AstroSolarTM !

Hold the filter at arms length towards the daylight sun to detect dangerous defects. S m all pinholes may become

visible but will not be dangerous, because the light going through w ill be dispersed across a wide area like in a

“camera obscura”. This scattered light how ever w ill cast a “hue of light” to slightly overlay the solar image information

and reduce image contrast somewhat.

For highest photographic perform ace and when using large telescope apertures at high magnification it is therefore

advisable to “blacken out” these pinholes. Use thick black laquer (black paint) and directly apply the paint onto the

inner (telescope) side of AstroSolarTM with a very thin, sharp brush to just cover the size of the pinhole while holding

the filter towards the sun.

Peter...

 

[RichM63]

Thanks guys, I'll follow your methods before using the filter. it looks OK but I've never observed through it.

First try out will be with the LifeCam as per Lunar so not actually directly looking at the Sun.

Rich..

[employee2-4601]

On ‎21‎/‎04‎/‎2016 at 09:25, RichM63 said:

Thanks guys, I'll follow your methods before using the filter. it looks OK but I've never observed through it.

First try out will be with the LifeCam as per Lunar so not actually directly looking at the Sun.

Rich..

 

I've never had any problems with mine. All the advice so far has been good and I can't add much to it. However, I will emphasise the comments re: checking there are no pinholes in the film. That said, I've found solar observation really rewarding and have never experienced any problems with the Baader filter.