Thread: Solar Filter
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Old 18-03-2015, 09:24 AM
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sil (Steve)
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Join Date: Jun 2012
Location: Canberra
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The Baader film is the way to go, just don't crinkle/crease it in any way to be safe. Its cheap enough to replace if you are concerned. It comes flat with protective boards. and if you're worried approaching the eyepiece, start with defocusing then find the sun, can be tricky, maybe add a moon filter/neutral density filter to your eyepiece if you have one as the sun will be bright still and might help contrast as you focus.

Still I've never heard of anyone having problem with baader film or even those cheap eclipse glasses but if you're still unsure then don't look at the sun and definitely don't go against the advice of what to do. Do NOT put baader film on your eyepiece (hoping to save money on covering a smaller hole) as the sun will be focused there and just burn through it. the filter needs to be the first thing the suns rays hit so the harmful wavelengths are blocked before the enter the optical train and get focused.

I used an older smaller scope i no longer use with a baader filter for solar viewing the transit of venus while photographing it. I made the scope filter using a piece of plumbing hardware the fitted the end of the scope. For my camera lens I used a step up filter ring that easily screws into the lens. in both cases i built my filter by carefully laying the sheet of baader film out flat, applying an even coating of glue (tarzans grip from memory) to the front edge of the ring i could attach to scope/camera then sitting the ring glue down onto the filter sheet and adding some weight so it sealed evenly and fimly then left it alone for a week for it to cure fully. then i added some glue to the excess and folded it up around the sides of the ring, maybe adding a rubber band or some tape to hold it flat in place, then leave it alone for a week then i ran black electricians tape around the side to make sure it was flat and sealed. This way the front of the filter stays flat and I wasn't "stretching" it over the end of something which risks stretching the filter and weakening its protective capabilities and avoids light leakage from the edge. Works a treat, looks good and i keep them safe in there own tupperware containers for storage. I suggest you first find something you can securely attach to the end of your scope before doing a DIY (eg: a replacement end cap you could cut the middle out of that you can securely attach the film onto). The film doesn't have to be perfectly flat, its wont make a difference, just don't scrunch it up into a ball in your pocket then stretch it over the front of a scope.

Also don't forget to cover your finderscopes so they don't become a hazard.

Yes there are alternative DIY methods for solar observing but the baader film is purpose made for the task to eliminate the harmful spectra parts other methods might only remove the visible light parts and leave other non-visible rays to come through.

I had similar reservations to you when i started solar and i now have a nice HA scope but the white light filters are still useful for quick observations of sunspots and dslr photography. I trust the baader film is doing its job, my stroke last year did more to my eyesight than anything else. Good luck!
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