Solar Filter Film Question

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Solar Filter Film Question

#1

Post by GCoyote »


I got 25% a discount on an 8 x 11" sheet of solar viewing film from Thousand Oaks.
Since the Post Office failed to destroy it in transit (just barely) I now have to cut it to fit one of my scopes.

I have enough for three or four attempts depending on which scope I apply it too. My first idea is to insert a disk of it under the dew shield of a 70 mm refractor. It seems to be pretty tight so I am not concerned that it would come off accidentally while I'm viewing the Sun. It also occurs to me that I can add a retaining screw if needed to be doubly sure it stays on.

Any reason this won't work? Have I missed anything?
Any metaphor will tear if stretched over too much reality.
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Re: Solar Filter Film Question

#2

Post by Star Dad »


I might suggest some double sided sticky tape and mount it to a ring if there is room / a place to attached it to the scope. You certainly want to make double darn sure that the film is in place. Having the dew shield in place should help prevent the wind from dislodging it. I'd suggest holding your hand up to the eyepiece before you look through it as a triple check on the status of the film being in place.
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Re: Solar Filter Film Question

#3

Post by GCoyote »


I got the scope used for few bucks so I can drill holes in it as needed. The dew shield just seems like the obvious place to start.
Any metaphor will tear if stretched over too much reality.
Gary C

Celestron Astro Master 130mm f5 Newtonian GEM
Meade 114-EQ-DH f7.9 Newtonian w/ manual GEM
Bushnell 90mm f13.9 Catadioptric
Gskyer 80mm f5 Alt/Az refractor
Jason 10x50 Binoculars
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Re: Solar Filter Film Question

#4

Post by Lady Fraktor »


GCoyote wrote: Fri Mar 26, 2021 2:29 pm I have enough for three or four attempts depending on which scope I apply it too. My first idea is to insert a disk of it under the dew shield of a 70 mm refractor. It seems to be pretty tight so I am not concerned that it would come off accidentally while I'm viewing the Sun. It also occurs to me that I can add a retaining screw if needed to be doubly sure it stays on.
Any reason this won't work? Have I missed anything?
You could make a disk that fits inside the dewshield pressed against the lens cell retainer ring.
As long as the dewshield cannot be knocked out of place by wind or people.
If you use a finderscope and do not want to remove it, make a filter for it as well.
See Far Sticks: Antares Elita 103/1575, AOM FLT 105/1000, Bresser BV 127/1200, Nočný stopár 152/1200, Vyrobené doma 70/700, Stellarvue NHNG DX 80/552, TAL RS100/1000, Vixen SD115s/885
EQ: TAL MT-1, Vixen SXP, AXJ, AXD
Az/Alt: AYO Digi II/ Argo Navis, Stellarvue M2C/ Argo Navis
Tripods: Berlebach Planet (2), Uni 28 Astro, Report 372, TAL factory maple, Vixen ASG-CB90, Vixen AXD-TR102
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Re: Solar Filter Film Question

#5

Post by GCoyote »


Lady Fraktor wrote: Fri Mar 26, 2021 6:24 pm ...

You could make a disk that fits inside the dewshield pressed against the lens cell retainer ring.
As long as the dewshield cannot be knocked out of place by wind or people.

Yeah, that is what I was thinking but I wanted a sanity check from more experienced observers.

Lady Fraktor wrote: Fri Mar 26, 2021 6:24 pm ...If you use a finderscope and do not want to remove it, make a filter for it as well.

Nice idea. I was going to take it off but this would be more useful.

Thanks!
Any metaphor will tear if stretched over too much reality.
Gary C

Celestron Astro Master 130mm f5 Newtonian GEM
Meade 114-EQ-DH f7.9 Newtonian w/ manual GEM
Bushnell 90mm f13.9 Catadioptric
Gskyer 80mm f5 Alt/Az refractor
Jason 10x50 Binoculars
Celestron 7x50 Binoculars
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(And a bunch of stuff I'm still trying to fix or find parts for.)
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Re: Solar Filter Film Question

#6

Post by Baurice »


There was an article by Phil Harrington on how to do it about 20 years ago. I cannot reproduce it here for copyright reasons. You make two rings of cardboard: one that fits over the telescope and the second fits over the first. You cut a piece of film about 2 inches larger than the diameter of your telescope. Place the film over the smaller ring and move the larger ring over the film and smaller one. If you glue the sides of the film to the smaller ring it helps.

You need to buy new film every few years, as it wears out.
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Re: Solar Filter Film Question

#7

Post by Thefatkitty »


Hi Gcoyote,

I read your post and thought that would be a neat idea. However, I'm thinking it might be a pain to insert and remove it. Solar film is also not something you want your fingers to touch as well.

The spacing for solar film from the objective doesn't matter either, at least from what I've seen. I bought a sheet of Baader film and made filters for my 102mm, 80mm, 60mm, and still had enough left for my 70mm. Four scopes for $50; can't beat that!

As well, the filter size can be smaller for the scope's objective; the Sun in my 80mm has a lot of black around it, whether with a lens or my DSLR, and the filter hole size is 70mm. It could easily do with a 60mm hole size.

They were really easy to make, and I've had 3+ years of trouble-free use. I used some thin plastic cut to fit around the dewshield, duct tape to hold that together, as well as hold the cardboard for the rest of it. I stapled the solar film to the cardboard; notice the wrinkles in the film. Trust me, you want that; don't stretch it so it's flat. It just won't work properly; a distorted image is the result.


2214221522162217


Still, I certainly don't know everything about all this, believe me... However, it's worked well; very easy to mount and unmount, no fiddling with the dewshield, my fingers never get anywhere near the film, and with just over 2 1/2 inches of "hold" on the dewshield, no chance of it falling/being blown off either.

All that being said, I'd still like to see what you come up with! :D

All the best,
Mark

"The Hankmeister" Celestron 8SE, orange tube Vixen made C80, CG4 & AZ-EQ5 mounts.
Too much Towa glass/mirrors.

H/A - PST stage 2 mod with a Baader 90mm ERF on a Celestron XLT 102 (thanks Mike!)
Ca-K - W/O 61mm, Antares 1.6 barlow, Baader 3.8 OD and Ca-K filters with a ZWO ASI174mm.
W/L - C80-HD with Baader 5.0 & 3.8 Solar film, Solar Continuum 7.5nm and UV/IR filters with a Canon EOS 550D.

Oh yeah, and Solar Cycle 25 :D
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Re: Solar Filter Film Question

#8

Post by GCoyote »


Thefatkitty wrote: Sat Mar 27, 2021 12:53 am Hi Gcoyote,

I read your post and thought that would be a neat idea. However, I'm thinking it might be a pain to insert and remove it. Solar film is also not something you want your fingers to touch as well.

The spacing for solar film from the objective doesn't matter either, at least from what I've seen. I bought a sheet of Baader film and made filters for my 102mm, 80mm, 60mm, and still had enough left for my 70mm. Four scopes for $50; can't beat that!

As well, the filter size can be smaller for the scope's objective; the Sun in my 80mm has a lot of black around it, whether with a lens or my DSLR, and the filter hole size is 70mm. It could easily do with a 60mm hole size.

They were really easy to make, and I've had 3+ years of trouble-free use. I used some thin plastic cut to fit around the dewshield, duct tape to hold that together, as well as hold the cardboard for the rest of it. I stapled the solar film to the cardboard; notice the wrinkles in the film. Trust me, you want that; don't stretch it so it's flat. It just won't work properly; a distorted image is the result.


2214221522162217


Still, I certainly don't know everything about all this, believe me... However, it's worked well; very easy to mount and unmount, no fiddling with the dewshield, my fingers never get anywhere near the film, and with just over 2 1/2 inches of "hold" on the dewshield, no chance of it falling/being blown off either.

All that being said, I'd still like to see what you come up with! :D

All the best,

I have two dirt cheap 70 mm scopes so I can set one up exclusively for solar. That has the added advantage that once I get it modified, I won't have to worry about setting it up again correctly for each use.
I like your filter holder and was going to go that route before I got the dew shield insert idea. I still have some rainy days ahead to experiment and a similar amount of filter material to play with.

Clear skies.
Any metaphor will tear if stretched over too much reality.
Gary C

Celestron Astro Master 130mm f5 Newtonian GEM
Meade 114-EQ-DH f7.9 Newtonian w/ manual GEM
Bushnell 90mm f13.9 Catadioptric
Gskyer 80mm f5 Alt/Az refractor
Jason 10x50 Binoculars
Celestron 7x50 Binoculars
Svbony 2.1x42 Binoculars
(And a bunch of stuff I'm still trying to fix or find parts for.)
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Re: Solar Filter Film Question

#9

Post by GCoyote »


Thefatkitty wrote: Sat Mar 27, 2021 12:53 am Hi Gcoyote,

... I stapled the solar film to the cardboard; notice the wrinkles in the film. Trust me, you want that; don't stretch it so it's flat. It just won't work properly; a distorted image is the result.


2214221522162217

...

I've though about this and it just now occurred to me why that might happen. Try to get it flat would very likely change the stress in different areas of the film. That would probably cause local differences in the orientation of the polymer chains resulting in different polarization strength and direction in different parts of the image.

Does that makes sense?

Gusty winds so no observing today.

Clear Skies!
Any metaphor will tear if stretched over too much reality.
Gary C

Celestron Astro Master 130mm f5 Newtonian GEM
Meade 114-EQ-DH f7.9 Newtonian w/ manual GEM
Bushnell 90mm f13.9 Catadioptric
Gskyer 80mm f5 Alt/Az refractor
Jason 10x50 Binoculars
Celestron 7x50 Binoculars
Svbony 2.1x42 Binoculars
(And a bunch of stuff I'm still trying to fix or find parts for.)
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Re: Solar Filter Film Question

#10

Post by Thefatkitty »


GCoyote wrote: Mon Mar 29, 2021 5:17 pm I've though about this and it just now occurred to me why that might happen. Try to get it flat would very likely change the stress in different areas of the film. That would probably cause local differences in the orientation of the polymer chains resulting in different polarization strength and direction in different parts of the image.

Does that makes sense?

Gusty winds so no observing today.

Clear Skies!

I'm honestly not positive as to why; seems to just be something solar folks say, but I do like your reasoning! I've also heard that stretching it will also cause "pinholes" in the film as well. Too many of those will also degrade an image, so I'm wondering if that's what it really is. I wish I could say for sure.

Hope you filter is working out :D

All the best,
Mark

"The Hankmeister" Celestron 8SE, orange tube Vixen made C80, CG4 & AZ-EQ5 mounts.
Too much Towa glass/mirrors.

H/A - PST stage 2 mod with a Baader 90mm ERF on a Celestron XLT 102 (thanks Mike!)
Ca-K - W/O 61mm, Antares 1.6 barlow, Baader 3.8 OD and Ca-K filters with a ZWO ASI174mm.
W/L - C80-HD with Baader 5.0 & 3.8 Solar film, Solar Continuum 7.5nm and UV/IR filters with a Canon EOS 550D.

Oh yeah, and Solar Cycle 25 :D
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Re: Solar Filter Film Question

#11

Post by Lady Fraktor »


Likely a combination of do not stretch it then heat it.
Possibly it could weaken the film over time.
See Far Sticks: Antares Elita 103/1575, AOM FLT 105/1000, Bresser BV 127/1200, Nočný stopár 152/1200, Vyrobené doma 70/700, Stellarvue NHNG DX 80/552, TAL RS100/1000, Vixen SD115s/885
EQ: TAL MT-1, Vixen SXP, AXJ, AXD
Az/Alt: AYO Digi II/ Argo Navis, Stellarvue M2C/ Argo Navis
Tripods: Berlebach Planet (2), Uni 28 Astro, Report 372, TAL factory maple, Vixen ASG-CB90, Vixen AXD-TR102
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Re: Solar Filter Film Question

#12

Post by GCoyote »


I ended up going with the Fatkitty solution. It's just easier to cut the approximate size square vs a perfect fit circle. On the plus side, the external mounting leaves no doubt whatsoever that the solar mod is currently installed.

Being somewhat OCD, mine is a bit more SteamPunk in execution.

I cut and taped the film to the back of bit of heavy duty cardboard.
Solar Filter Holder 20210612 -1sm.jpg
I cut the center out of a clean pet food scoop and bolted the filter to that.
One side of some Velcro gets attached to the scoop.
Solar Filter Holder 20210612 -2sm.jpg
The scoop is a good fit for a 60 or 70 mm refractor, keeping the filter from sliding off to one side.
I put the other half of the Velcro around the OTA and added a rubber band purely out of paranoia.
Solar Filter Holder 20210605 -4sm.jpg
In use.
Solar Filter Holder 20210605 -3sm.jpg
Any metaphor will tear if stretched over too much reality.
Gary C

Celestron Astro Master 130mm f5 Newtonian GEM
Meade 114-EQ-DH f7.9 Newtonian w/ manual GEM
Bushnell 90mm f13.9 Catadioptric
Gskyer 80mm f5 Alt/Az refractor
Jason 10x50 Binoculars
Celestron 7x50 Binoculars
Svbony 2.1x42 Binoculars
(And a bunch of stuff I'm still trying to fix or find parts for.)
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Re: Solar Filter Film Question

#13

Post by Thefatkitty »


I really like that, well done! Also you had the idea for a bigger piece of cardboard, good for shielding you from the Sun. Wish I'd thought of that :lol: Great way to attach it too :D

Hope you get some clear skies to try it!

All the best,
Mark

"The Hankmeister" Celestron 8SE, orange tube Vixen made C80, CG4 & AZ-EQ5 mounts.
Too much Towa glass/mirrors.

H/A - PST stage 2 mod with a Baader 90mm ERF on a Celestron XLT 102 (thanks Mike!)
Ca-K - W/O 61mm, Antares 1.6 barlow, Baader 3.8 OD and Ca-K filters with a ZWO ASI174mm.
W/L - C80-HD with Baader 5.0 & 3.8 Solar film, Solar Continuum 7.5nm and UV/IR filters with a Canon EOS 550D.

Oh yeah, and Solar Cycle 25 :D
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Re: Solar Filter Film Question

#14

Post by GCoyote »


Thefatkitty wrote: Mon Jun 14, 2021 12:56 am I really like that, well done! Also you had the idea for a bigger piece of cardboard, good for shielding you from the Sun. Wish I'd thought of that :lol: Great way to attach it too :D

Hope you get some clear skies to try it!

All the best,

I already have a plan for the "Mark II" :geek:

I think a sheet of 1/4" foam core poster board would be perfect for an integrated sun shade. Light, stiff, easy to cut. My wife is going watch the copy room at work for a discarded chunk.
Any metaphor will tear if stretched over too much reality.
Gary C

Celestron Astro Master 130mm f5 Newtonian GEM
Meade 114-EQ-DH f7.9 Newtonian w/ manual GEM
Bushnell 90mm f13.9 Catadioptric
Gskyer 80mm f5 Alt/Az refractor
Jason 10x50 Binoculars
Celestron 7x50 Binoculars
Svbony 2.1x42 Binoculars
(And a bunch of stuff I'm still trying to fix or find parts for.)
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Re: Solar Filter Film Question

#15

Post by OzEclipse »


These are very robust. have been using the same filters & holders for solar eclipses since I designed this holder in 2002.
https://joe-cali.com/eclipses/EQUIPMENT ... lters.html
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