Need help finishing DIY solar filter

[Victor Boesen]

So I've just sketched and printed my own 3D-parts which will make up the solar filter for my Skywatcher Evostar 72ED and my next step is mounting the solar filter itself. Before I do anything I'd just like to get your opinion on how I should mount it. I've thought about gluing the filter to the bottom of the gray part with som gorillaglue but I don't know if it will destroy the film??

Clever ideas are welcome!

Victor

[Peter Drew]

I don't think the glue will cause a problem, just avoid getting any on the area in use as you can't really clean the filter. The filter material is very light and tricky to handle during the construction process. I would recommend putting a thin bead of adhesive round the maximum diameter of the holder and then carefully drop it on to the filter material that has been laid on a flat surface. Remember that the filter material needs to be in a relaxed state, not tight like a drum skin, wrinkles have no affect on the performance.    😀 

[Victor Boesen]

19 minutes ago, Peter Drew said:

I don't think the glue will cause a problem, just avoid getting any on the area in use as you can't really clean the filter. The filter material is very light and tricky to handle during the construction process. I would recommend putting a thin bead of adhesive round the maximum diameter of the holder and then carefully drop it on to the filter material that has been laid on a flat surface. Remember that the filter material needs to be in a relaxed state, not tight like a drum skin, wrinkles have no affect on the performance.    😀 

Thanks! I'll give the glue a go:)

[Victor Boesen]

Update:

I glued the film on today and gosh it was difficult.... I ended up with a small spot of glue in the bathroom of the film in the picture. The film sits tight but not stretched(I can gently tap it) I'm gonna leave it like this for now:)

Victor

[Peter Drew]

Looks perfect.    😀

[Victor Boesen]

12 minutes ago, Peter Drew said:

Looks perfect.    😀

Thanks Peter! Just had it out for a spin. No sunspots visible of course but the rim seemed to focus nice and sharp. I did however have trouble observing the granulation which I've heard should be visible. I'll create a post later asking for some tips for observing the sun(getting a sunshade is already one of them).

EDIT: A quick lookup of observing granulation gets me thinking my small 3" scope will need some godly conditions though faculae seems like a better contestant:)

Victor

Edited August 21, 2019 by Victor Boesen

[Rusted]

Good job on the filter!

I can see surface texture in my 90mm when the power is high enough. So a 3" should be enough.
The scale may be even smaller than you imagine.
This image is deliberately forced to bring out the surface texture.
You wouldn't normally see it like this with the naked eye.
But you get an idea for what to look for in scale.

 

[Victor Boesen]

8 minutes ago, Rusted said:

Good job on the filter!

I can see surface texture in my 90mm when the power is high enough. So a 3" should be enough.
The scale may be even smaller than you imagine.
This image is deliberately forced to bring out the surface texture.
You wouldn't normally see it like this with the naked eye.
But you get an idea for what to look for in scale.

 

Mange tak Rusted:) - Thank a lot Rusted, I've been looking up what magnification I should use and come to the conclusion that the higher the better of course but you know how it is in Denmark with the conditions so 60+ mag should do it? I did feel like I saw what other people have described granulation(grainy but almost boiling) but only at steady times. I'm not sure I'm mistaking it with floaters since I was using my 4.7mm which gives me an exit pupil of 0.8mm??

Your experiences are appreciated Rusted:)

Victor

Edited August 21, 2019 by Victor Boesen

[Rusted]

Hej Victor! Det var så lidt. 

I've just noticed your location. Small world, isn't it?   Though I'm only here on loan. Not a real Dane.

Do you have a Barlow lens to get higher powers?
A star diagonal is good for relaxed viewing too. I find it helps with the floaters. 
Floaters usually wander slowly across your field of vision. Not really like fixed, fine surface texture.
Hopefully you'll have some sunspots to enjoy before very long.

 

[Victor Boesen]

16 minutes ago, Rusted said:

Hej Victor! Det var så lidt. 

I've just noticed your location. Small world, isn't it?   Though I'm only here on loan. Not a real Dane.

Do you have a Barlow lens to get higher powers?
A star diagonal is good for relaxed viewing too. I find it helps with the floaters. 
Floaters usually wander slowly across your field of vision. Not really like fixed, fine surface texture.
Hopefully you'll have some sunspots to enjoy before very long.

 

It is indeed:)) I do have a 2.5X barlow but I'm questioning the optics inside of it since I got it when I just gotten my first telescope...
It's this one
https://www.kikkert-teleskophuset.dk/shop/25-barlow-linser/265-astro-25x-apo-barlow-linse-125/
Might just be because of the high magnification but I've used it on the moon, jupiter and now the sun and it seemed to introduce a bit more false color in the rim and a little softness(possibly because of high magnification though).

I'll receive my star diagonal in a week from now probably since I ordered it together with the refractor but it wasn't in stock at the time.

I'm excited to see the mercury transit in november which is also one of the reasons why I designed and 3D-printed my own filter:)

Edited August 21, 2019 by Victor Boesen

[Rusted]

I have no experience of that particular Barlow. As you say, it might be the high powers you are using.
The seeing conditions and often the altitude of the object under study are vitally important here.
Early morning and sometimes the late afternoon can be steadier. If the object is in sight then.

The obvious way to prove it is a good or a poor Barlow is to borrow a different one from somebody.
Do you belong to an  astro club? That is often a good way to be able to make direct equipment comparisons.
Or to have first hand advice on what is good or not so good equipment. Astronomy clubs and societies can be a great way to gain knowledge quickly.
There are also Danish astro forums of course. Where people have much more local knowledge of Danish sourced equipment.

Mercury is absolutely tiny compared with the sun. So don't expect more than a really tiny, dark blob.
My first attempt to capture some pictures of a Mercury transit with a digital camera on my 90mm were poor. NO practice!
If you want to capture some good shots of Mercury you need to practice capturing the sun sharply.

Do you have a telescope adapter for your Nikon? You may need extension tubes to reach focus. People here can advise.
Balancing a heavy camera could be very difficult. Don't take any chances with the equipment toppling and causing damage!
I found Venus much easier to see and to photograph in transit because it is so much bigger!

Edited August 22, 2019 by Rusted

[Victor Boesen]

30 minutes ago, Rusted said:

I have no experience of that particular Barlow.
As you say, it might be the high powers you are using.
The seeing conditions and often the altitude of the object under study are vitally important here.
Early morning and sometimes the late afternoon can be steadier. If the object is in sight then.

The obvious way to prove it is good or poor Barlow is to borrow a different one from somebody.
Do you belong to an  astro club? That is often a good way to be able to make direct equipment comparisons.
Or to have first hand advice on what is good or not so good equipment.
Astronomy clubs and societies can be a great way to gain knowledge quickly.
There are also Danish astro forums of course where people have much more local knowledge of Danish sourced equipment.

Mercury is absolutely tiny compared with the sun. So don't expect more than a small, dark blob.
My attempts to capture some pictures of Mercury with a digital camera on my 90mm were hopeless. 
If you want to capture some good shots of Mercury you need to practice first.
Do you have a telescope adapter for your Nikon?
Venus is much easier to see and to photograph.

I'm not a part of a club but I'm doing some meetups with a couple of people here and there and I could ask them. I saw the mercury transit a couple years ago so I know it's going to be tiny:) I do have an adapter for my Nikon so I'll try to get a photo of it:) As much as I would observe a Venus transit it will be another 98 years before it happens again and it won't even be visible from Europe....

[Rusted]

I just checked. There is Frederiksberg Astro Society.

https://astronomisk.dk/wieth-knudsen-observatoriet/

Astronomisk Selskab - Danmarks landsdækkende forening for astronomi

They have a 150mm solar telescope!  A real one!

https://astronomisk.dk/?p=103

Not like my home made one.

[Victor Boesen]

2 hours ago, Rusted said:

I just checked. There is Frederiksberg Astro Society.

https://astronomisk.dk/wieth-knudsen-observatoriet/

Astronomisk Selskab - Danmarks landsdækkende forening for astronomi

They have a 150mm solar telescope!  A real one!

https://astronomisk.dk/?p=103

Not like my home made one.

What a view it must be!

Would a polarizing filter improve my chances of viewing faculae etc?? I feel like the view is "overexposed"

[Rusted]

If the image is too bright then rotating one polarizing filter against another will allow fine adjustment of brightness.
Or you can use an ND [Neutral Density] filter. 

The real question is: Why does the image seem too bright?  It shouldn't.
Have you used the [wrong type] of photo solar foil instead of the standard visual type?
Have you checked the filter for pinholes or damage without the telescope?
Just hold it up and use the tiny sun to test the filter as you move it around in front of your face.
Any damage will show as local brightening or glare from pinholes.

Which solar protection filter film did you use? 
 

[Victor Boesen]

1 hour ago, Rusted said:

If the image is too bright then rotating one polarizing filter against another will allow fine adjustment of brightness.
Or you can use an ND [Neutral Density] filter. 

The real question is: Why does the image seem too bright?  It shouldn't.
Have you used the [wrong type] of photo solar foil instead of the standard visual type?
Have you checked the filter for pinholes or damage without the telescope?
Just hold it up and use the tiny sun to test the filter as you move it around in front of your face.
Any damage will show as local brightening or glare from pinholes.

Which solar protection filter film did you use? 
 

I've already checked it for holes:)

I was aware I shouldn't get the photographic film so I bought the ND5.0:
https://www.firstlightoptics.com/solar-filters/baader-astrosolar-safety-film-nd-50.html

It nowhere near painfully bright but it's just the lack of contrast. Would a the baader continuum filter help improving contrast??

[Stu]

The continuum filter can help bring out features such as faculae and granulation. If you have a narrowband filter like a UHC or OIII you could try these too as they can help improve the views if you don't want to buy more stuff already!

One thing I've seen is people not knowing about the clear protective film which sits on one side of the solar film when shipped and should be removed. I assume this is still used, but worth checking as it reduces the quality of the view. Some comments in it towards the end of this thread.

 

[Rusted]

I like the Baader Solar Continuum too and it does noticeably reduce the brightness.
Not sure about its ability to protect against excessive UV/IR though.
I don't think it should be considered a safety device. Not remotely cheap either!

[Victor Boesen]

2 hours ago, Stu said:

The continuum filter can help bring out features such as faculae and granulation. If you have a narrowband filter like a UHC or OIII you could try these too as they can help improve the views if you don't want to buy more stuff already!

One thing I've seen is people not knowing about the clear protective film which sits on one side of the solar film when shipped and should be removed. I assume this is still used, but worth checking as it reduces the quality of the view. Some comments in it towards the end of this thread.

 

I wasn't aware of this although reading the manual is also confusing(to me). The filter is already sandwiched between two types of paper.

And the manual says the following:

I tried cutting a small piece of the film and I couldn't find any sort of plastic film... 

Thanks for the tip with the UHC/OIII filter. I'll give it a go

Edited August 23, 2019 by Victor Boesen

[Victor Boesen]

I've just been out for a look and the OIII really improved the view. It was much more relaxing to look at and the rim of the sun focused sharp no problem. Another plus when using filter is that false color is eliminated:) No surface details were visible but I'm aware that the sun is quite featureless at this current moment 

Victor

[Stu]

47 minutes ago, Victor Boesen said:

I've just been out for a look and the OIII really improved the view. It was much more relaxing to look at and the rim of the sun focused sharp no problem. Another plus when using filter is that false color is eliminated:) No surface details were visible but I'm aware that the sun is quite featureless at this current moment 

Victor

Good stuff. It sounds like they may have changed the packaging to make it more obvious ie paper both sides.

Granulation is very seeing dependent. I think Rusted mentioned earlier that mornings and late afternoon can often be the best times as the atmosphere has yet to heat up, or is starting to cool down. It's ironic because you might think midday would be best as the sun is highest, but it rarely is.

[Chriske]

Rusted, Victor,

What a coincidence, Wieth Knudsen...!!, I met the man 40 years(or so) ago. He was a well known observer. We invited the man at our observatory Urania (Hove-Belgium). He gave a lecture on occultations.

Edited August 23, 2019 by Chriske