Hole in a solar filter .

[Krishnam kalra]

I was using a solar filter . And due to a mistake , a hole is created at the centre of the filter . Can i do something to rapair it or should a buy a new solar film ? 

[coatesg]

How big and is the filter still taut (assuming it's a mylar film type filter?)? A small piece of opaque material (paper sticker, duct tape, etc) stuck over the hole would make the filter safe to use if it's a pinprick size hole, but beware of the filter suddenly splitting if the hole is larger and affects the structural integrity of the filter - this would be very dangerous if the filter was in use at the time. 

[Jojo204]

7 hours ago, Krishnam kalra said:

I was using a solar filter . And due to a mistake , a hole is created at the centre of the filter . Can i do something to rapair it or should a buy a new solar film ? 

If I were you I’d be safe and buy a new filter.

You have many sets of filters available but only one set of eyes! 😜

[rockinrome]

On 03/07/2019 at 22:27, Jojo204 said:

If I were you I’d be safe and buy a new filter.

You have many sets of filters available but only one set of eyes! 😜

AGREED!

 

[farunj]

Hi,

Please do NOT use a solar filter that has a hole in it! It is very very dangerous and will definitely blind you. Just go for a new filter.

The best way to test if a filter is fine or not is to hold it up to the sun with your naked eyes and seeing if you can get any light through the filter. If there is even a tiny hole through which light passes, then just throw the filter away and buy a new one. 

As Jojo said, you only have one set of eyes!

Varun.

[Stub Mandrel]

Perfectly safe if you can fit a patch over the hole that you are 100% happy is secure. No less risky than glueing the film into a card support ring, which 100s of people have done before you.

[johninderby]

This is Baader’s advice.

“Before each solar session carefully inspect your AstroSolar filter for mechanical damages, broad scratches, streaks,extensive whipe marks and other quality degrading influences. Small pinholes do not degrade the eye safety or image sharpness of AstroSolar !
Hold the filter at arms length towards the daylight sun to detect dangerous defects. Small pinholes may become visible but will not be dangerous, because the light going through will be dispersed across a wide area like in a “camera obscura”. This scattered light however will cast a “hue of light” to slightly overlay the solar image information and reduce image contrast somewhat.”

Edited July 10, 2019 by johninderby

[Gfamily]

11 minutes ago, johninderby said:

This is Baader’s advice.

“Before each solar session carefully inspect your AstroSolar filter for mechanical damages, broad scratches, streaks,extensive whipe marks and other quality degrading influences. Small pinholes do not degrade the eye safety or image sharpness of AstroSolar !
Hold the filter at arms length towards the daylight sun to detect dangerous defects. Small pinholes may become visible but will not be dangerous, because the light going through will be dispersed across a wide area like in a “camera obscura”. This scattered light however will cast a “hue of light” to slightly overlay the solar image information and reduce image contrast somewhat.”

Correct. A small hole stays the same size when you put it in front of a telescope, so it doesn't let any more light through when you put it in front of a telescope.

And has been said, the eyepiece will spread it out over a much larger area of the retina than doing the test for holes itself will. 

However, if there are multiple holes, or signs of larger areas being worn etc, obviously it would be reasonable consider binning the filter. 

[johninderby]

Now this is one BIG solar filter. 🙀

Hope it doesn’t need replacing too often. 😁

Edited July 10, 2019 by johninderby

[RT65CB-SWL]

On 03/07/2019 at 14:55, Krishnam kalra said:

I was using a solar filter . And due to a mistake , a hole is created at the centre of the filter . Can i do something to rapair it or should a buy a new solar film ? 

If it is one you have made yourself... buy new solar film and make another!

I don't know what 'scope you are using, but if you own a refractor, I would go for a Herschel wedge. (see image below).

Even glass solar filters are not 100% immune from defects. That is why I have gone and got a Herschel wedge, (that's mine in the above image above), to replace my aging Thousand Oaks Type ll.

Edited July 11, 2019 by Philip R

[Ben the Ignorant]

https://www.teleskop-express.de/shop/product_info.php/language/en/info/p11398_Baader-2459286---AstroSolar-Filterfolie---Visuell---ECO-size-140x155mm---sichere-Sonnenbeobachtung.html

Baader recently introduced a new small format of solar film, if your scope is no larger than 130mm (plus 5mm of clearance on each side) this 140mmx155mm will do and cost very little.

But why a rectangular sheet, you ask, since a square would leave less leftover film? Because the leftover can be used to cover the finder and/or a very small scope.

[MarsG76]

Personally I'd get the baader solar film sheets and be replacing the film on the filter...

[SIDO]

I would replace it if ;

1. The slightest imperfection is found.

2. Refer to answer 1.

Solar visual observation is always a risk taking endeavor, if anyone were to ever guarantee otherwise or take for granted just for a second this fact serious injury could result.

I don't take chances, filters are cheap...

                        Freddie.

                      

[JOC]

10 hours ago, johninderby said:

Now this is one BIG solar filter.

What a stonking telescope I wonder how big that is?  It wouldn't disgrace a major observatory!  Is that a 20"+ Dob-mob job?

[johninderby]

It’s a 42” dob. 🙀

[JOC]

1 minute ago, johninderby said:

It’s a 42” dob

Wow!  I think that's one of the biggest I've seen a picture of on SGL outside of a formal observatory.  It just looks like it is in someone's garden.  What a stonking telescope.  Sorry to de-rail the thread, but WOW!

[johninderby]

Yes WOW indeed. Here’s another pic. Check out the step ladder need for observing. 

[JOC]

5 hours ago, johninderby said:

Yes WOW indeed. Here’s another pic. Check out the step ladder need for observing.

There must come a time when telescope size must give a whole new meaning to nudging the scope.  I know it's probably for DSO use (lots of light gathering), but I bet the planets look fantastic through something that size.

[Stub Mandrel]

A 0.25mm hole lets through as much sunlight as the full aperture of a 76mm scope with Baader film on it, but it will be defocused by diffraction and won't come to a point of focus.

A typical pinhole will be much smaller. You would need 25 tiny pinpricks 0.05mm across to let as much light through.

And how can sticking a patch on your film be less safe than sticking your film into a frame?

 

[Krishnam kalra]

On 11/07/2019 at 03:06, Ben the Ignorant said:

https://www.teleskop-express.de/shop/product_info.php/language/en/info/p11398_Baader-2459286---AstroSolar-Filterfolie---Visuell---ECO-size-140x155mm---sichere-Sonnenbeobachtung.html

Baader recently introduced a new small format of solar film, if your scope is no larger than 130mm (plus 5mm of clearance on each side) this 140mmx155mm will do and cost very little.

But why a rectangular sheet, you ask, since a square would leave less leftover film? Because the leftover can be used to cover the finder and/or a very small scope.

I have an 8" dob.