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Solar filter question..


skippyinspace
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Hi,

I was thinking about purchasing a ready made solar filter for my Celeston advanced 8" Newtonian.

My question is what size do I buy, I'm convinced when I measured the outside tube diameter I got 204, Which doesnt seam to fit the measurments on the websites.

I assume I can go bigger and find a way to secure it

Any thoughts?

Thanks

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Or you could buy baader astro solar film for a lot less money than a ready made filter, I'm surer there's an easy way to secure it. This is what i will be doing very soon.

Good luck

Adamski

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I ordered a premade Baader solar filter for my C6-NGT and it works perfectly. It snaps into the end of the tube just like the dust cap does. For the 6 inch reflector it was approx 59 USD from High Point Scientific.

Still going to order a sheet for my Binoculars, for funsies.

John

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Sorry to jump on this thread but I was looking at the considerable difference between the film and the ready made filter (£15 v £70) so was going to buy the film but couldnt work out if they gave you everything you need to make it up or if they just give you the film?

Sounds like a stupid question but for £55 difference it made me think.

Justin

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You get a sheet of film and then figure out a way to affix it to the opening of your viewing device.

There are some instructions in one of the threads that give info on how to make something to hold them.

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Neil

Good work! I went through the Baader instructions and was worried about light "creeping in" around the edges if my cutting out was a bit off or it slipped during use, so I went for something that wrapped around the end of the scope. The thread with the details is [thread=137388]here[/thread]

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Neil

Good work! I went through the Baader instructions and was worried about light "creeping in" around the edges if my cutting out was a bit off or it slipped during use, so I went for something that wrapped around the end of the scope. The thread with the details is [thread=137388]here[/thread]

Hi Ash,

Just had a look at your link.

Very nicely done, looks very professional.

Edited by tibbs1972
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When using Baader paper as a solar filter, you should check the filter every time before use for any small holes or other damage. If there is any damage, even very minor you should destory that filter and start again. The sun will blind you in a split second if there is any damage to the filter. If in doubt do not use!

Peter

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  • 2 weeks later...

Do you think it would be wise to sandwich the Baader film between 2 layers of clear plastic? I'm assuming it doesn't get hot and as such this would reduce the chance of damager to the film?

Just an idea ...

Edit: something like this? Also seems very reasonable on cost.

http://www.sheetplastics.co.uk/Acryllic_Disk_Circles/Clear_Acrylic_Discs_circles

Edited by Crunchard
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Do you think it would be wise to sandwich the Baader film between 2 layers of clear plastic? I'm assuming it doesn't get hot and as such this would reduce the chance of damager to the film?

Just an idea ...

Edit: something like this? Also seems very reasonable on cost.

Clear Acrylic Discs/ Circles - cut to size

Bad idea actually as it would cause a lot of distortion. Plastic sheet is nowhere near being optically flat.

The Baader film is actually very, very strong. I used it for many years and never had the slightest bit of damage.

John

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Thanks John, I might not fully understand but I doubt I could make a solar filter out of Baader film alone and make that anywhere near optically flat either, certainly the many pictures on SGL indicate a sizable level of unflatness (word creation time).

I can't see how a piece of perspex that is also not optically flat would cause any more distortion? Or have I missed something really obvious? :D

Cheers

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Although the Baader film may not be physically flat when it's properly installed in a loose state that isn't under tension it is effectively optically flat in terms of distortion. I know it seems to contradict common sense but that's the way the film works.

This link will explain a lot:

http://www.baader-planetarium.com/sofifolie/details_e.htm

Plastic sheet is horrendous optically and will really spoil the view.

John

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Ah I get you now ... see I was missing something really obvious!

The perspex would have it's own effect on the viewing, introducing unknown viewing issues - although it would keep the Baader film nice and flat :p

I'll get my coat ... :D

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...certainly the many pictures on SGL indicate a sizable level of unflatness (word creation time).

Check out the pics in the link I posted earlier in the thread. The film in my DIY filter cell is a bit "saggy" and it's not fully bonded to the cell to allow for expansion. In use, and even having used white plastic for the holder, the holder expands pulling the film flat without stretching it. Whether this is by accident or design I don't know, but I've had it on the end of the scope for 2.5 hours in full Sun and it's not torn or gone out of shape.

On your point about clear plastic, the film did delaminate when I first built the cell as the double sided tape strips used to stick the filter rings/film sandwich together was stronger than the film laminations! Left me with the silverised layers intact and stuck to one ring, and the outer clear protective layer of film stuck to the other ring. Stuck it back together carefully and it seems to work fine...

Good luck (however you build it) - Let us know how you get on.

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You're actually supposed to remove the clear film and throw it away before fitting the Baader solar film. The clear film isn't actually bonded to the solar film, it's just there to protect the solar film during packaging and shipping. It will actually degrade the quality of the image if you leave it in place.

John

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Eh? :D I'll take your word for it, but I'd never have managed to separate the layers - the fine clear layer stayed attached throughout the cutting/build/sticking etc, even rubbing an off-cut between my fingers to see how durable it was nothing parted. (I wouldn't have known it was there until it parted of its own accord 2 days later). There certainly was a fine tissue paper-like protective sheet over the film - that got binned OK.

Well, you live and learn...

I'll see if I can re-part it and what difference it makes to the view/images. I was chuffed with what I'd got from it, so I'm looking forward to being extra chuffed now!

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Thanks John - hadn't seen that one. I'd agree with the OP in that thread - there's nothing in the Baader instructions about removing the layer. Now we know different. If this is the only mistake I make in this hobby then I'll be happy. Trouble is, I know it wont be...:D

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OK. Carefully constructed solar filter cell now carefully de-constructed and clear film removed. Peeling thin film off double-sided tape was (ahem) "challenging". Solar film (thankfully undamaged) cell reconstructed just in time for the Sun to disappear behind the rooftops. Grrr...

I'm sure the view will have improved without the film - I'll let you know next time I get chance to try it out.

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