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Solar film

Skooby

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Skooby

Skooby

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Hi guy I'm going to make my own solar filter but not sure how much I should buy as it's quite expensive. My question is how much do you think I'll need for a 10" scope 250pds? Does it all need to be covered or will an a4 baader solar sheet be enough thanks

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Skooby

Skooby

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That's what I thought is 8 inches wide and around 11 inches long and that's £18 on flo and for the next up it's over £50 no in between roll crazy. Thanks though.

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RT65CB-SWL

RT65CB-SWL

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Hi Skooby,

Have you considered an off-axis solar filter?

In other words, does your end cap/cover have another smaller removable cap?

If "Yes!", then that maybe your best option. Also when making your homemade solar filter, it is recommend you do not have the solar film perfectly smooth. I cannot remember the reason for this as it does not cause any degradation of the 'final' view.

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Bizibilder

Bizibilder

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Just make one as big as you can from a sheet of A4 film and use that or, maybe more complicated, make one off-axis about 4" in diameter - so the light passes through the secondary spider arms.  With Solar viewing it is the heat from the Sun itself that mucks up the atmosphere making the seeing bad.  It is a rule of thumb that 4" aparture will allow you to see everything that a larger aparture would.  i.e. the image is atmosphere limited rather than aparture limited.

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Peter Drew

Peter Drew

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You should be able to make an off-axis mask with an apertue of 3.5"-4" that will fit in the unobstructed path between the spider vanes. This would be an ideal white light aperture and leave plenty of film over for a replacement in due course if necessary. :smiley:

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ramstar

ramstar

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You might want to check the integrity of the film before you start on your filter. I didn't and after quite a lot of time, effort and a few quid spent in making it, I found it was riddled with pin holes so ended up binning it. Not sure if they were due to something I'd done or not, even though I thought I was being careful all the way through the process. I was not a happy bunny I can tell you!

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Skooby

Skooby

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Thanks for all your replies guys some really useful information I've googled the off axis filter and It doesn't look to hard to make. Thanks for that. And wookie thanks for that link wow that's gotta be the cheapest I've seen that is tempting I must say :) once again though thanks all.

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Peter Drew

Peter Drew

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Perfectly OK, the main caveat from a performance point of view is that 10" aperture is rather overkill for solar viewing. You could of course add a further outer smaller off-axis mask without filter film to the 10" filter when conditions don't support the main aperture.  :smiley:

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Chris Rowland

Chris Rowland

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When I made a solar filter for my NS11 I made an off axis filter of the maximum size that would fit between the edge and the obstruction.  IIRC it was an 80mm circle.  I made two disks of foam board with a hole in them, held a square of film to one with double sided tape then fitted the other with more double sided tape.  Lots left over from and A4 sheet for binoculars, small scopes etc.

Chris

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Skooby

Skooby

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Thanks guys I'm gonna give one way a try or buy the one from 365 astronomy but looking at that one on 365 astronomy the edges look quite thick if I could make one and have the edge coming in just over 2 inches I could then do it out if the a4 sheet so that would mean that about just over 71/2 inches of solar film will be showing. Do you think that will do? Thanks.

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Skooby

Skooby

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Sammyb that looks good looks pretty straight forward thanks for the picture. And jb80 thanks for the pic and what size is your scope and what size film did you get? Thanks.

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Skooby

Skooby

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Thanks yeh I'll also make a cover for the finder scope. Yeh I'd also like to make my own but it is scary if it came off or something that would be the last thing i see outta that eye!!

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JB80

JB80

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Sammyb that looks good looks pretty straight forward thanks for the picture. And jb80 thanks for the pic and what size is your scope and what size film did you get? Thanks.

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Hi Skooby,

This is only a 6" filter, you could easily make it to be a 6" one from the A4 sheet you would just need to cut the cardboard rings to suit. I followed this set of instructions if it helps... http://www.baader-planetarium.com/sofifolie/bauanleitung_e.htm

I ended up with a roll for Christmas but I wanted the ND3.8 which I could only find in a roll and it's only good for use with a camera so you can't observe visually using the ND3.8.

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