Solar Filter

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Jnicholes United States of America
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Solar Filter

#1

Post by Jnicholes »


I have an 80 mm refractor, focal length is 900 mm. I'm just curious if anybody knows of a solar filter that would fit my telescope. I'm completely new to solar viewing, And I know you need a solar filter before you try or else you will go blind.

Does anybody have any recommendations for a solar filter?
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Re: Solar Filter

#2

Post by stewe »


I always used Solar safety films and worked very well. As opposed to glass filters, they do not color the image and you cannot brake them :) Check out, for example the Baader safety films:
https://www.baader-planetarium.com/en/s ... 80mm).html
You can buy them with an adjustable mounting bracket that fits your scope's diameter.
And one word of advice: I recommend using some duct tape in addition to the bracket's fastening mechanism to fix the filter bracket to the telescope tube. One cannot be cautious enough when it comes to Solar observations.
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Re: Solar Filter

#3

Post by Dragonsfire »


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Re: Solar Filter

#4

Post by Lady Fraktor »


The Baader Solar Film gives the best resolution for white light viewing and there are many examples of how to build a cell to hold it in place.
Just be sure the cell fits over your dewshield snugly and there is no chance of it falling off or being blown off in a breeze.
Also either make one for your finder if a optical one or just remove it completely.
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Re: Solar Filter

#5

Post by Thefatkitty »


Hi, I have pretty much the same scope. I used Baader film (IMO the best) and you can look on the net as Gabby said for ideas. It's quite easy; some cardboard and duct tape will do. Just be sure to leave the film so it's wrinkly, not pulled flat.
The solar finderscope I made from an L-bracket welded to a 3/4" wide piece of steel and some plastic with a long bolt. You can even get a 3/4" wide L-bracket; might be easier... You move the scope so the shadow of the bolt disappears, and there's the Sun in your eyepiece/camera!

I've had mine for 3 years, no problems :D
01.JPG
02.jpg
03.JPG
Image003.png

Just some ideas, but it does put up a great image, especially during no Solar minimum... ;)

I took this over the weekend, just because it was clear out for once. This is an example of what you could probably get; I used a lowly Canon T3.
Sun_2020_02_05_s.png

Remember, always be safe! :)
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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

#6

Post by Jnicholes »


Thanks, guys. I appreciate it. I forgot to mention that I'm just exploring the idea, it's not set in stone if I'm going to do it or not.

I might just do it as soon as I get the money to get The proper filter.
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Re: Solar Filter

#7

Post by JayTee »


For your size scope, you can make a solar filter using an 8"X8" sheet of Baader solar film (Amazon $20) and the top of a Pizza box (Dominos $8) as long as there is no grease on it! Once you have these supplies, you'll need a pair of scissors and tape (Scotch, Masking, Duct take your pick). This is one of the simplest DIYs for our scopes.

CAVEAT: it may be a simple build but if it leaks light, disastrous consequences result! So just pay attention to what you're doing and build it carefully.

Cheers,
JT
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Re: Solar Filter

#8

Post by OzEclipse »


I've used this style made from sheet filter materials for more than 20 years.

http://joe-cali.com/eclipses/EQUIPMENT/ ... lters.html

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Re: Solar Filter

#9

Post by TCampbell »


In white light filters, you can use solar film ... like these: http://thousandoaksoptical.com/shop/sol ... solarlite/
(NOTE: these fit over the front of the telescope like a cap/cover. This means they are sized based on the physical diameter of the front of your optical tube... not the optical aperture.)

OR... for highest levels of clarity, you can use a Herschel wight light "Solar Wedge". I have one made by Lunt: https://luntsolarsystems.com/shop/solar ... ar-wedges/

That's the one I have ... but you can search for "white light solar wedge" or "herschel wedge" to find others.

Note that a weight light "solar wedge" (aka Herschel wedge) replaces the diagonal at the BACK of the telescope. There is no filter on the front of the scope. This means that ALL of the energy of the sun passes through the scope. For this reason, pay strict attention to the size recommendations. They are typically best on refractors of 4" or smaller. The light passes through the scope and hits the diagonal ... which has a heat sink to off-load heat. Instead of a solid mirror, it's somewhat transparent glass so that only a tiny percentage of light is reflected up to the eyepiece and most of the light passes through to the heat sink.

These wedges are more expensive (e.g. $300) but I've used numerous white light filters on the front of various scopes ... and nothing comes even remotely close to the level of detail I can see through the wedge.

Due to a side-effect of the way these work, they end up polarizing the light. This means if you put a linear polarizer on the end of the eyepiece, you can rotate the eyepiece to dim the brightness of the sun when viewing.

Also, when doing 'white light' through a refractor, Baader makes something called the "solar continuum filter" (it's green). It's a broadband filter which narrows the spectrum to reduce chromatic aberration (color fringing) common in achromatic refractors to produce a sharper image.



You can go in a completely different direction by getting into Hydrogen alpha solar observing. But this is a lot more expensive.
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Re: Solar Filter

#10

Post by Michael131313 »


I just got through making a DIY solar filter with Baader Solar Film from Agena ($20). Pretty much followed the enclosed instructions. Made it to fit on the dew shield of my AR102. I used heavy poster board which was probably overkill. It is rock solid and I added two strings on either side so I could tie it securely to the scopes handle and rail. Works great.
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Re: Solar Filter

#11

Post by Burris »


if you have a dedicated "SOLAR" scope like a Lunt, it can take the heat. But with a regular SCT, MAK, or refractor, use solar film on the front/ objective lens. They are not designed to take the heat passing thru the optical tube. Bill
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Re: Solar Filter

#12

Post by Harmonious »


A sheet of solar film is the way to go for the highest cost/benefit ratio. I've made several using a variety of materials for the frames. Just use material that does not quickly degrade in sunlight.

I'm sure the commercial jobs with frames are nice, but here is the thing, the most important thing. there is very little to see in a white light filter. We are in a long period of low sun spot activity, really no sunspots to see. https://sohowww.nascom.nasa.gov/data/re ... i_igr/512/

Put it off until we come out of the minimum or spend a great deal more for a setup that will allow you to see proms and surface details.
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Re: Solar Filter

#13

Post by Baurice »


Jnicholes wrote: Mon Feb 24, 2020 11:21 pm Thanks, guys. I appreciate it. I forgot to mention that I'm just exploring the idea, it's not set in stone if I'm going to do it or not.

I might just do it as soon as I get the money to get The proper filter.
As this is an awfully bad solar minimum, there's no rush. Sunspots have been very rare recently.
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Re: Solar Filter

#14

Post by Baurice »


TCampbell wrote: Fri Mar 06, 2020 3:28 pm In white light filters, you can use solar film ... like these: http://thousandoaksoptical.com/shop/sol ... solarlite/
(NOTE: these fit over the front of the telescope like a cap/cover. This means they are sized based on the physical diameter of the front of your optical tube... not the optical aperture.)

OR... for highest levels of clarity, you can use a Herschel wight light "Solar Wedge". I have one made by Lunt: https://luntsolarsystems.com/shop/solar ... ar-wedges/

That's the one I have ... but you can search for "white light solar wedge" or "herschel wedge" to find others.

Note that a weight light "solar wedge" (aka Herschel wedge) replaces the diagonal at the BACK of the telescope. There is no filter on the front of the scope. This means that ALL of the energy of the sun passes through the scope. For this reason, pay strict attention to the size recommendations. They are typically best on refractors of 4" or smaller. The light passes through the scope and hits the diagonal ... which has a heat sink to off-load heat. Instead of a solid mirror, it's somewhat transparent glass so that only a tiny percentage of light is reflected up to the eyepiece and most of the light passes through to the heat sink.

These wedges are more expensive (e.g. $300) but I've used numerous white light filters on the front of various scopes ... and nothing comes even remotely close to the level of detail I can see through the wedge.

Due to a side-effect of the way these work, they end up polarizing the light. This means if you put a linear polarizer on the end of the eyepiece, you can rotate the eyepiece to dim the brightness of the sun when viewing.

Also, when doing 'white light' through a refractor, Baader makes something called the "solar continuum filter" (it's green). It's a broadband filter which narrows the spectrum to reduce chromatic aberration (color fringing) common in achromatic refractors to produce a sharper image.



You can go in a completely different direction by getting into Hydrogen alpha solar observing. But this is a lot more expensive.
The last point is very true. I consider myself lucky to own anything at all but I'm not getting much from my Coronado PST because the Sun is so quiet.
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Re: Solar Filter

#15

Post by Baurice »


TCampbell wrote: Fri Mar 06, 2020 3:28 pm In white light filters, you can use solar film ... like these: http://thousandoaksoptical.com/shop/sol ... solarlite/
(NOTE: these fit over the front of the telescope like a cap/cover. This means they are sized based on the physical diameter of the front of your optical tube... not the optical aperture.)

OR... for highest levels of clarity, you can use a Herschel wight light "Solar Wedge". I have one made by Lunt: https://luntsolarsystems.com/shop/solar ... ar-wedges/

That's the one I have ... but you can search for "white light solar wedge" or "herschel wedge" to find others.

Note that a weight light "solar wedge" (aka Herschel wedge) replaces the diagonal at the BACK of the telescope. There is no filter on the front of the scope. This means that ALL of the energy of the sun passes through the scope. For this reason, pay strict attention to the size recommendations. They are typically best on refractors of 4" or smaller. The light passes through the scope and hits the diagonal ... which has a heat sink to off-load heat. Instead of a solid mirror, it's somewhat transparent glass so that only a tiny percentage of light is reflected up to the eyepiece and most of the light passes through to the heat sink.

These wedges are more expensive (e.g. $300) but I've used numerous white light filters on the front of various scopes ... and nothing comes even remotely close to the level of detail I can see through the wedge.

Due to a side-effect of the way these work, they end up polarizing the light. This means if you put a linear polarizer on the end of the eyepiece, you can rotate the eyepiece to dim the brightness of the sun when viewing.

Also, when doing 'white light' through a refractor, Baader makes something called the "solar continuum filter" (it's green). It's a broadband filter which narrows the spectrum to reduce chromatic aberration (color fringing) common in achromatic refractors to produce a sharper image.



You can go in a completely different direction by getting into Hydrogen alpha solar observing. But this is a lot more expensive.
The last point is very true. I consider myself lucky to own anything at all but I'm not getting much from my Coronado PST because the Sun is so quiet.
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