Author Topic: Lets talk sun filters for se8 scope  (Read 371 times)

Eric Shaffer

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Lets talk sun filters for se8 scope
« on: December 24, 2017, 02:13:44 AM »
Questions Questions and moreQuestions. I received my new scope.  I was considering a sun filter to the moon and sun at the day time.  This way.  I can get us to my scopewhen it's light out.  I would prefer a good filter for both sun and moon for my scope.  Here is a joke for everyone.Went to establish my scope uplast night.  Forgot to take of my celebrity sense cap off.  Keep mentioning 8 -12 stars located on a cloudy night.  It was late and I could see a celebrity their.  I was to excited to see my very first thing thru my new scope.So that the laugh is on me.



Anthony Graham

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Re: Lets talk sun filters for se8 scope
« Reply #1 on: December 29, 2017, 05:08:16 AM »
For nice, well made solar filters look at Kendrick. Great product.

http://www.kendricka...larfilters.html

handthedemo

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Re: Lets talk sun filters for se8 scope
« Reply #2 on: December 29, 2017, 02:00:43 PM »
I have found that the baader astrofilm allows me to see the greatest detail. This is compared to glass and black polymer.
I have also found that the column of air between you and the sun is very turbulent,
and you just can't crank up the power like night time viewing.  I have seen the best results with refractors, 80 or 100mm and having the highest useful mag of about 100x.  Instead of a full aperture filter you could try to make an off axis filter with a small piece of astrofilm. I don't have an SCT to test.
maybe someone here has some tips for you specific to SCTs.

Todd Treser

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Re: Lets talk sun filters for se8 scope
« Reply #3 on: December 30, 2017, 02:48:33 AM »
I have used a glass Thousand Oaks solar filter with my 8" SCT for the past two decades and have been happy with the level of detail it provides. I usepowers of 125 - 225x depending onthe seeing. I keep hearing the astrofilm is better, but I haven'treally done a side-by-side.I will probably try the astrofilm on a 110mm f7 EDrefractor soonwhich should give me an idea of whether or notthe film has the potential toprovide more detail.

scolposnimbworr

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Re: Lets talk sun filters for se8 scope
« Reply #4 on: December 31, 2017, 08:41:53 AM »
I would suggest an off-axis solar filter as well...
You might be able to squeeze a simulation of a 70mm f/29 achromat out of the Schmidt...

One of many instructions found online...

http://www.sfsidewal...-your-telescope

The solar film... http://www.highpoint...OSrAaAvZF8P8HAQ

Brandon Costello

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Re: Lets talk sun filters for se8 scope
« Reply #5 on: December 31, 2017, 03:53:58 PM »
Quote
I have found that the baader astrofilm allows me to see the greatest detail. This is compared to glass and black polymer.
I have also found that the column of air between you and the sun is very turbulent,
and you just can't crank up the power like night time viewing.  I have seen the best results with refractors, 80 or 100mm and having the highest useful mag of about 100x.  Instead of a full aperture filter you could try to make an off axis filter with a small piece of astrofilm. I don't have an SCT to test.
maybe someone here has some tips for you specific to SCTs.

Just putting together info until I can put it all together. Thanks for info. I have a starting point.

Jeremy Butler

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Re: Lets talk sun filters for se8 scope
« Reply #6 on: December 31, 2017, 10:40:50 PM »
Quote
I would suggest an off-axis solar filter as well...

C8 70mm off-axis.jpg

You might be able to squeeze a simulation of a 70mm f/29 achromat out of the Schmidt...

One of many instructions found online...

http://www.sfsidewal...-your-telescope

The solar film... http://www.highpoint...OSrAaAvZF8P8HAQ

So how do you make one? Just cut a circle and put it in the tube?

Quote

I have used a glass Thousand Oaks solar filter with my 8" SCT for the past two decades and have been happy with the level of detail it provides. I usepowers of 125 - 225x depending onthe seeing. I keep hearing the astrofilm is better, but I haven'treally done a side-by-side.I will probably try the astrofilm on a 110mm f7 EDrefractor soonwhich should give me an idea of whether or notthe film has the potential toprovide more detail.

Do you just cut a circle and put it in the end of the tube? Or is their some kind of clamping device like a hoop?

Charlie Carpenter

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Re: Lets talk sun filters for se8 scope
« Reply #7 on: January 01, 2018, 02:06:18 AM »
I made a mask out of cardboard.  Mine was not off axis, I cut a concentric hole in the cardboard (80mm) then I cut out a matching piece of black construction
paper, so the inside was black.  The outside diameter was the diameter of my dew shield.  Next I cut a one inch strip of cardboard and glued it around the perimeter of this circle.  This makes a ring which clinches the outside
of the scope. Now I am really nervous about solar viewing so after this was made , in addition to the ring clutching the scope, I taped it to the front of the scope so no wind could come and blow it off.  I used masking tape as it leaves the least residue on the scope body.

For your SCT see the above pic to make an off axis mask.

Daniel Ferguson

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Re: Lets talk sun filters for se8 scope
« Reply #8 on: January 08, 2018, 03:56:25 AM »
Quote
Quote

I would suggest an off-axis solar filter as well...

C8 70mm off-axis.jpg

You might be able to squeeze a simulation of a 70mm f/29 achromat out of the Schmidt...

One of many instructions found online...

http://www.sfsidewal...-your-telescope

The solar film... http://www.highpoint...OSrAaAvZF8P8HAQ

So how do you make one? Just cut a circle and put it in the tube?

This is an example of a ready-made off-axis solar filter, and on a Schmidt-Cassegrain...

https://i.ytimg.com/...xresdefault.jpg

Off-axis filters are used on telescopes that use mirrors and possess a secondary obstruction...
...Schmidt and Maksutov Cassegrains, and Newtonians. The goal is to place the off-axis film diameter between the outer edge of the full aperture and the outer edge of its secondary obstruction; and in the case of a Newtonian, the spider-vanes must also be avoided. The remaining aperture, without the solar film, must be covered, and opaque...
...else, the telescope would be damaged, along with the observing eye. Also, the finderscope must be either removed or capped, for additional safety.

You can make an off-axis filter with materials as simple or as elaborate as you would like; cardboard, or wood, or metal as some of the ready-mades....

https://stargazerslo...-1343067218.jpg

The entire body of the filter to slip over the end of the optical-tube would not be unlike that of a cover for a round hat box...

https://cfl-createfo.../153381-4-1.jpg

The filter-body can be made with the same material such as that. The filter must fit snugly, so that it does not pop off when bumped or when the wind blows, for that would also result in damage to the telescope and the observer, in an instant. Safety is of paramount importance when observing the Sun, and when constructing any solar filter.

The Sun is the largest object in the sky; as such, it doesn't need a telescope with a large aperture, hence the suggestion of an off-axis filter.

These instructions come with the Baader solar film...

http://astrosolar.co...a-or-telescope/
These may be included as well... http://astrosolar.co...ve-filter-cell/

The solar film must not be stretched when installing. Double-sided tape is often used to fasten the film around and about the solar aperture. The film should be larger than the opening when using the tape. The film should be allowed to simply fall onto the tape under its own wieght without stretching or wrinkling it. There will be some waviness to it after it's installed, but that is acceptable. Such will not affect the views...

https://www.optcorp....99mm-od-c00.jpg

This member made an off-axis filter for his Schmidt, using commonly-available materials, and one for the finderscope too...

http://www.cloudynig...er#entry6316880






linghetade

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Re: Lets talk sun filters for se8 scope
« Reply #9 on: January 09, 2018, 07:41:41 PM »
I have only had one experience with an off-axis and it was on someone else's C11 SCT as I recall. It was some sort of film that made the suna slightlybluish tint. He also had a bino-viewer connected and the interpupillary distance was too tight for me or my son. I adjusted focus some and tried one eye and then the other, but although I got it focused based on the edge ofthe discthere was essentially no detail available other than limb darkening, not even noticeable granulation. My son had the same experience with it. This was on a day with nosunspots anyway, but even on such days my SCT with full aperture glass filter always shows granulation/orange peel and somesort of brightening or darkening somewhere, usually closer to the limbs. I don't know if it was seeing, or the film, or something else but it was the worst look at the sun I've ever head.

Stephen Moritz

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Re: Lets talk sun filters for se8 scope
« Reply #10 on: January 10, 2018, 01:22:51 AM »
Heya,

As mentioned, off-axis and smaller will do you well to cut the light down so you can see detail and save you money and headaches on a big scope.

I made the mistake of buying a glass filter for my SCT, the full size of it, and while it worked and I could see sunspots, it was way less detailed than film. I didn't listen to advise on this forum, I was niaeve and I bought the glass filter, a big one. Ultimately I sold it and picked up a Baadar Solarfilm filter from Astrozap that fit my scope and it's way, way better and it cost a 3rd of the price to boot.

Note, you will not want to use the same filter for the sun & moon. They are incredibly different in terms of brightness. You won't see the moon through a real sun filter hardly at all even on a full moon supermoon night.

For the moon, if your focal ratio isn't enough to drop it to comfortable viewing, just grab a 13% transmission ND filter and you should be able to take a look at it with a very bright setup and this is a cheap filter to get (sized to your eyepiece).

Very best,

sainomaters

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Re: Lets talk sun filters for se8 scope
« Reply #11 on: January 10, 2018, 04:38:25 PM »
Quote
Heya,

As mentioned, off-axis and smaller will do you well to cut the light down so you can see detail and save you money and headaches on a big scope.

I made the mistake of buying a glass filter for my SCT, the full size of it, and while it worked and I could see sunspots, it was way less detailed than film. I didn't listen to advise on this forum, I was niaeve and I bought the glass filter, a big one. Ultimately I sold it and picked up a Baadar Solarfilm filter from Astrozap that fit my scope and it's way, way better and it cost a 3rd of the price to boot.

Note, you will not want to use the same filter for the sun & moon. They are incredibly different in terms of brightness. You won't see the moon through a real sun filter hardly at all even on a full moon supermoon night.

For the moon, if your focal ratio isn't enough to drop it to comfortable viewing, just grab a 13% transmission ND filter and you should be able to take a look at it with a very bright setup and this is a cheap filter to get (sized to your eyepiece).

Very best,

I've also read that for planets that you might want a reducer. Then you can get the whole planet in view and not just part. Thanks for the tip. Soon I'll be getting one. Waiting for the moon to show up. Plus I need to play with scope a little more.

cicacating

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Re: Lets talk sun filters for se8 scope
« Reply #12 on: January 11, 2018, 04:59:28 AM »
Quote
Quote

Heya,

As mentioned, off-axis and smaller will do you well to cut the light down so you can see detail and save you money and headaches on a big scope.

I made the mistake of buying a glass filter for my SCT, the full size of it, and while it worked and I could see sunspots, it was way less detailed than film. I didn't listen to advise on this forum, I was niaeve and I bought the glass filter, a big one. Ultimately I sold it and picked up a Baadar Solarfilm filter from Astrozap that fit my scope and it's way, way better and it cost a 3rd of the price to boot.

Note, you will not want to use the same filter for the sun & moon. They are incredibly different in terms of brightness. You won't see the moon through a real sun filter hardly at all even on a full moon supermoon night.

For the moon, if your focal ratio isn't enough to drop it to comfortable viewing, just grab a 13% transmission ND filter and you should be able to take a look at it with a very bright setup and this is a cheap filter to get (sized to your eyepiece).

Very best,

I've also read that for planets that you might want a reducer. Then you can get the whole planet in view and not just part. Thanks for the tip. Soon I'll be getting one. Waiting for the moon to show up. Plus I need to play with scope a little more.
Planets are so tiny that you will not want a reducer.

ontoolhaiworl

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Re: Lets talk sun filters for se8 scope
« Reply #13 on: January 11, 2018, 09:20:53 AM »
I use a variable polariser when viewing objects that are too bright...

http://agenaastro.co...ing-filter.html

You can fine-tune the level of brightness, or the level of dimness(vice-versa), from allowing only 2% of the total light through, and up to as much as 40%. Here's my own to demonstrate. You simply attach the polariser to an eyepiece, or star-diagonal, and then rotate the two halves to adjust...
Such may also be used when viewing the Sun, if necessary, but only with a safe solar filter in place over the aperture.

This one is perhaps of the best quality... http://agenaastro.co...ilter-1-25.html

The reason I make mention of it is due to the fact that it will be integrated within the optical train, or path, and therefore its inclusion and quality will affect the quality of the final image. The same is true of any optical component, whether eyepieces or optical accessories; barlows, other types of filters, the star-diagonal, etc.

You can also create a variable polariser by simply screwing two of these together...

http://agenaastro.co...ing-filter.html


piatimascomp

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Re: Lets talk sun filters for se8 scope
« Reply #14 on: January 11, 2018, 09:48:44 AM »
"I've also read that for planets that you might want a reducer."

An 8" Schmidt has a native focal-length of 2032mm, and to observe the planets at most any size. A 32mm Plossl will realise only 64x...

2032 ÷ 32 = 63.5x

Planets are best seen at 100x and above, especially Saturn. Schmidts, and Maksutovs, are chosen for that very thing; long refractors as well. Reducers are for squeezing out a wider field-of-view for observing the larger of deep-sky objects, and larger portions of the sky in general. If you want one for deep-sky, or for a distant view of a tiny planet with a larger sky background for perspective, then by all means. Observing the Sun and Moon might benefit more from a reducer, at times.