Solar Filter

[joncrawf]

Hi all

I wondered what folks thoughts on a mod I'd like to make to my Baader solar filter (astrozap). I'm using a SW200P and I'm worried about damaging the film while I'm observing (perhaps putting my finger through it). I wondered about cutting a disc of 3mm clear polycarbonate and fixing it over the filter aperture.

I understand the desire most of you will have to minimise the amount of 'stuff' between  your eye and the object being observed but I only have one functioning eye, so I'd be in deep trouble if anything happened to it! I'm happy to accept a small loss of performance in exchange for greater eye safety.

Is there any reason why I should NOT do this? Perhaps I'm fussing too much. How delicate is the film; would I have to be ridiculously clumsy to puncture it?

Thanks in advance for your answers!

Jon

[Floater]

Hi, Jon. Yes, I do think you would have to be very clumsy to accidentally puncture the film. It is quite substantial.

And if you make it a ritual to check for pinholes before observing you should be fine. Just hold the filter up to the light - but not the sun, remember.

Further I'm pretty sure that there is something about the chances being very slim that any damage on one side of the film will match any damage on the other side. Not certain about that, have a look at Baader or even FLO's site.

Summing up, you'll be fine if you just take care, think through what you're doing and follow a 'ritual' for setup.

Enjoy.

[laudropb]

I would endorse all that Gordon has said. With proper care and attention you should have no problems with the filter. I have used mine for more than a year now with no problems. Always check the filter before use and ensure it is safe to view through. As for the effects of the polycarbonate, I have no idea, but I would have thought if they are not detrimental to the view manufacturers would have included it long ago.

[ArmyAirForce]

Putting anything non-optical quality over it, especially plastic, is going to destroy any detail that could be seen. There will be all sorts of distortions in the plastic that will kill fine detail.

Make or buy a decent box to keep it in to protect it when not in use. I have thin plywood covers for my 8 inch filter, and the smaller 80mm filter goes in a plastic box when not being used. Just be careful when you fit at, and after that, you shouldn't be poking around the end of the scope anyway. When you remove it, put it straight back in its storage box.

 

[Owmuchonomy]

The information provided with the film is very comprehensive.  It actually says in section 5 of the safety instructions "small pinholes may become visible but will not be dangerous...".  I don't know whether I would chance it or not as that statement is somewhat subjective.  If you look hard enough though the film when new there does seem to be very small 'pinholes' in it.

[Louis D]

I used to have a Thousand Oaks glass solar filter with dozens of pinholes in the coatings.  The amount of UV and IR making it through was quite negligible.  I much prefer my Baader film which has yet to develop a single pinhole in over 15 years of occasional use.  I always keep a sheet of cardboard over the stored front filter surface to protect it.  Since it's formed into a tube that slides over the end of my scope, the back is pretty well protected in storage already.  It's similar to mylar; that is, tough.  Just make sure it is snugly attached to the front of the scope.  Mine slides 3 inches over the end in a custom made "cell" that must be wiggled off.  No one is going to knock it off accidentally, nor is the wind going to take it.

[joncrawf]

Thanks for the replies. I guess the film is more durable than it looks. I'll get around to making a storage container for the filter but for the time being it's in it's original 'pizza box' in which it was delivered.

Thanks again

[michael.h.f.wilkinson]

The pizza box tends to keep the film safe, I have found

[laudropb]

That's what mine is stored in too.

[Floater]

And mine. Three filters; three 'pizza boxes'.

Jon, while you are absolutely right to prioritise safety, don't spoil your enjoyment by being too fearful. As in my original reply - and as others have written - these filters are fairly substantial and, with sensible care, you'll be fine.