worried - pin holes in baader solar filter...

[toc (Tim)]

A few days ago I picked up a solar filter from york optical for my C8. Ive used it a few times, but I am a bit nervous I must admit - There are a few faint pin holes here and there. Should I stop using it and ask for a refund, or is this perfectly ok? So far I am not blind, but I am worried that there might be some cumulative effect for long term observation....

[Ian Robinson]

Send it back.

[Starkler (Geoff)]

I would send it back too.

[Merlin66 (Ken)]

I've got and use Baader, 1000 Oaks and JMB solar filters.
The mylar based Baader can have some pinholes in the coating, if we're talking about say 6 or so spread across the whole aperture, there's no serious risk.
More cosmetic than dangerous.
Baader do suggest, if you want, to touch-up the pinholes with a TEXTA.
If it's brand new, straight out the box, I would try to get a better replacement.

[Ian Robinson]

Originally Posted by Merlin66

I've got and use Baader, 1000 Oaks and JMB solar filters.
The mylar based Baader can have some pinholes in the coating, if we're talking about say 6 or so spread across the whole aperture, there's no serious risk.
More cosmetic than dangerous.
Baader do suggest, if you want, to touch-up the pinholes with a TEXTA.
If it's brand new, straight out the box, I would try to get a better replacement.

No try in it , if it's brand new , you have a right to have it replaced or a full refund if it's defective.

[[1ponders] (Paul)]

It's not unusual for solar film to have very small holes in it. It's the same as for the mirror of a newtonian, if you hold some of them up to a bright enough light you will see "holes" in the coating (as viewed from the back.) SMALL holes in a solar film are not dangerous. If you can see them without shining the sun through it though....send it back!!!

[Wavytone]

What's more as the filter ages it will probably develop more. Almost all the metal film filters I have ever seen do, except the Questar ones and they cost a LOT more.

What you do:

Obtain some thick opaque paint - tippex correcting fluid will do nicely,

Hold the filter up to the sky so you can see the holes - or holding it against a computer screen might do in a dark room,

Use the applicator to place a dab of tippex over each hole. This should enhance contrast in your image, and makes no discernable difference to resolution.

Eventually when the filter looks like a road sign that has been used for target practice its time to bin it.

[Dennis]

Here is a link to the English translation of the specs of the Baader AstroSolar™ Film.

Here is a copy of what they write:

Start copy:
Eye safety:
AstroSolar™ is essentially free from pinholes, since - other than with even the most expensive glass filters - it is coated on both sides, so that the chance of two pinholes overlapping each other is extremely faint. Pinholes do appear, but to 1 out of 10000 only in optical density 2.5! Baader AstroSolar™ safety film has been approved for eye safety by the National Bureau of Standards in Germany, the PTB. Unlike any other Solar Filter on the market, AstroSolar™ is CE-tested according to EG-Norm 89/686 and EN 169/92 ( notified body 0196). All processes connected to this product have been thoroughly tested. Coatings are inspected constantly for consistency to ensure your eye safety!
End copy.

Cheers

Dennis

[toc (Tim)]

Thanks for the info everyone

The pin holes are only visible when directly over the sun - they are not visible just by holding it up to even bright lighting, so I guess it should be ok.

I think I might keep it, (its the proper Celestron one that mounts directly on the end of the C8) since it was the last one in the shop.

The view was interesting, but kind of boring - only very faint detail and no sun spots Guess I will have to wait until some appear.

[astroron (Ron)]

Hi Tim, I have had a 1000 Oaks filter for my Celestron 20cm for over twenty years, it has some pin holes in it which I just put some whiteout on and have had no trouble observing the Sun and also imaging it in that time.
Ron