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It works! Was: Solar - quick safety check. Now: Filter made what will I see please?


JOC
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So the story so far - to see what might be seen I bought a set of certified cardboard eclipse glasses to see roughly what the sun might look like.  These have arrived and it is interesting to see the sun like that.

Somewhat encouraged I've bought this:  https://www.telescopehouse.com/explore-scientific-solarix-solar-filter-film-a4.html as it was a bit cheaper than the Baader one.  If I make up the solar filter as described in the packet - I may make the circles a little bit bigger as the film is only just wide enough for my OTA, check I have no gaps, and put it over the end of my telescope then remove the finderscope or replace it with a home made pinhole one will I then be safe to place an eyepiece into my telescope and see what can be seen if I aim it at the sun?  I don't want to melt anything - particularly my eyes!

NB.  On the subject of a home-made pinhole camera style finderscope - if I make one that has something like tracing paper at the back to see the image through how do you know how long the tube has to be to get the image roughly in focus (I hope that's not a daft question)

Many thanks

Edited by JOC
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Just make sure that there is no way for the film to blow or fall off.  Particularly if this is for your 200P flextube a gust of wind from behind could blow the filter off.  Do you have a shroud? I don't think it is safe to use an unshrouded flex tube in the day.

 

For the finder the focal length of a pinhole camera is determined by the hole diameter.

 

For this purpose though it does not need to be in focus, my solar finder is a U shaped metal bracket with a small hole in one side and a punched point on the other.  The side with the hole is towards the sun so when the light shines directly through it the spot of light is on the punched hole.

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D4N That's a good point, it is for my flex-tube (my only telescope, but I want to get as much use as possible from it so hope that we can also look at the sun) but I think my DIY job here might do the trick:

It wraps around one and a half times fastens with press-studs and secures above and below the truss tube mounting points and is made from triple thickness thick nylon as I didn't fancy cutting it so folded it up instead.  Does that sound safe enough?

Maybe if there is enough material I will make a shroud for my finder too,  It may even be possible to kilter up some mounting points on the home made filters and add in some elastic with hooks that I can fasten to somewhere on the telescope to help hold them on.  I have a RA finder so wouldn't need to be looking at the sun to aim it.  Mind you I do like the simplicity of the idea of the small hole in the U shaped bit of metal as a solution - simple and elegant! 

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A dull and cold afternoon presented itself yesterday so this is what I have made.

IMG_3743.thumb.JPG.57792709c0bf7d8af0cb3ca63a9b6e70.JPGIMG_3744.thumb.JPG.126f4cc12edf4f14a49b7b14057bd767.JPG

 

It's made of photo mount board and I've put three eyelets around the edge so that I can tie some fasteners onto it to stop it blowing off. My hole cutter only went to 8 inches and given the size of my board it all started to get a bit difficult to work out how I could make it with what I had so in the finish its finished up with an 18cm aperture rather than the 20cm the telescope is capable of, but knowing how I can get a view of the moon through the 4" plastic inset hole I can't see that the reduced aperture will prevent me from getting a view.  It's difficult to take a shot of the shiny side without getting a rippled effect, but I think it's quite useably flat.  I've found a nice plastic box that it fits into nicely to protect it.  If I find the round edge gets tatty I'll just edge that with gorilla tape as I did the top.  The collar is about 3" deep.  There is also sufficient film left to make one for my RACI finder, but that's a project for another day.

Does it look sufficiently serviceable to be safe please?

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All looks good to me, provided the fixing between the board and the collar that goes onto the scope is solid then there should be no problems.

One thing to note, the film works best when not under any stress or tension, so ripples are good rather than bad :) 

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Thanks both.

Yup, I figure if I hold it up to general good daylight that any flaws should be evident.  One thing about a square top is there is plenty to grab hold of.  Looking at the pack it came in I think the templates on the inside of the cardboard packet with a slightly smaller hole will make one for the finder-scope.  I wanted a fairly robust construction that would last for a fair time for the big main filter and the mount board seemed the ideal sort of material, but I think that's probably overkill for the finderscope and the lightweight card supplied for the job looks ideal I'll just cut the holes slightly smaller.  I had an unused Fiskars hole cutter from my attempts at crafting a long time ago and that cut the holes quite well, I had a bit of a game getting them lined up each side as it wouldn't cut through from a single side, but it worked in the finish.  Will I need to paint it black inside (which sounds messy/fiddly) or should it work OK as is?

Needless to say its been 100% cloud cover all morning (sorry folks in Essex - yes, I did make a solar filter yesterday so it's all my fault) :clouds1: .  Assuming that I get out at some point in the next few days what should I look out for?  The packet says I should see an orange tinted sphere, but apart from hearing about 'sun-spots' I know precisely zero about what I might see with it.  It's Explore Scientific Solarix Solar filter film.   NB.  This might sound a daft question, but I assume that there is no reason why I shouldn't try taking photo's of what I see by attaching my DSLR to the focuser like I do when I take a picture of the moon - with the filter in place I won't damage the camera will I?

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On a good day and assuming there are some, you will be able to see sunspots, their umbra and penumbra and possibly the radiating fibrills, faculae which look like patches of slightly brighter material and in really good seeing and higher magnification, the surface granulation. Bear in mind when looking at sunspots that one at the disc centre is nearer to you than one at the edge by a distance greater than from you to the Moon and that despite appearing black, a sunspot isolated in space would be too bright to look at.   :icon_biggrin:

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9 minutes ago, Peter Drew said:

Bear in mind when looking at sunspots that one at the disc centre is nearer to you than one at the edge by a distance greater than from you to the Moon

Wow!

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48 minutes ago, JOC said:

Thanks both.

Yup, I figure if I hold it up to general good daylight that any flaws should be evident.  One thing about a square top is there is plenty to grab hold of.  Looking at the pack it came in I think the templates on the inside of the cardboard packet with a slightly smaller hole will make one for the finder-scope.  I wanted a fairly robust construction that would last for a fair time for the big main filter and the mount board seemed the ideal sort of material, but I think that's probably overkill for the finderscope and the lightweight card supplied for the job looks ideal I'll just cut the holes slightly smaller.  I had an unused Fiskars hole cutter from my attempts at crafting a long time ago and that cut the holes quite well, I had a bit of a game getting them lined up each side as it wouldn't cut through from a single side, but it worked in the finish.  Will I need to paint it black inside (which sounds messy/fiddly) or should it work OK as is?

Needless to say its been 100% cloud cover all morning (sorry folks in Essex - yes, I did make a solar filter yesterday so it's all my fault) :clouds1: .  Assuming that I get out at some point in the next few days what should I look out for?  The packet says I should see an orange tinted sphere, but apart from hearing about 'sun-spots' I know precisely zero about what I might see with it.  It's Explore Scientific Solarix Solar filter film.   NB.  This might sound a daft question, but I assume that there is no reason why I shouldn't try taking photo's of what I see by attaching my DSLR to the focuser like I do when I take a picture of the moon - with the filter in place I won't damage the camera will I?

You can keep an eye on one of the solar monitoring sites which show images of what is currently visible, example here:

http://www.solarham.net/regions/map.htm

This is an iPhone shot with the full disk visible showing some of the sets of features you might see. Also a higher power, processed image showing what you might see on a good day with better seeing.

The reality is that it will probably be somewhere in between ;) 

IMG_3735.JPG

IMG_0354.JPG

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8 minutes ago, Stu said:

You can keep an eye on one of the solar monitoring sites which show images of what is currently visible, example here:

http://www.solarham.net/regions/map.htm

This is an iPhone shot with the full disk visible showing some of the sets of features you might see. Also a higher power, processed image showing what you might see on a good day with better seeing.

The reality is that it will probably be somewhere in between ;) 

Thanks for this Stu - I'll book mark that site on my phone and then I can compare what I see with what should be there :-D  It sort of looks like someone has splattered it with ink - so those are what people colloquially call 'sun spots'?

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16 minutes ago, JOC said:

Thanks for this Stu - I'll book mark that site on my phone and then I can compare what I see with what should be there :-D  It sort of looks like someone has splattered it with ink - so those are what people colloquially call 'sun spots'?

Yes indeed, they can be strange looking beasts!

My knowledge of solar nomenclature is not what it should be, but yes, a sunspot is one of the features on its own, usually a dark umbra surrounded by a lighter area of penumbra. When gathered together in more complex groups they are known as Active Regions. Smaller black spots without penumbra are pores I believe.

If you get into it more, this is a very useful book.

https://www.firstlightoptics.com/books/observing-the-sun-book.html

 

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I did it!  I see'd da sun!!

I couldn't see anything like the sun spots, but I took a photo anyway - about 17:10 tonight

I also thought I'd show a picture of my setup with the filter.

I'm still in the process of fashioning a finder, but in its absence I found the easiest thing to do was to look directly through the focuser unit.  When I was close I could see the small sun in the main mirror, and when I moved it to the centre everything looked yellow and I could see it in the EP.  It seemed to work as a solution tonight, but it's def. no easy to find.  I'm going to try and make a shadow based finder as I think it will even be difficult with a filter protected RACI.

Hooray, Hooray a successful outing for the telescope - even then I had to wait about an hour for the sun to reappear - it disappeared the moment I went in for an EP originally this afternoon.

 

scopesun2sm.jpg

scope sun1sm.jpg

Solsm.jpg

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34 minutes ago, JOC said:

I did it!  I see'd da sun!!

I couldn't see anything like the sun spots, but I took a photo anyway - about 17:10 tonight

I also thought I'd show a picture of my setup with the filter.

I'm still in the process of fashioning a finder, but in its absence I found the easiest thing to do was to look directly through the focuser unit.  When I was close I could see the small sun in the main mirror, and when I moved it to the centre everything looked yellow and I could see it in the EP.  It seemed to work as a solution tonight, but it's def. no easy to find.  I'm going to try and make a shadow based finder as I think it will even be difficult with a filter protected RACI.

Hooray, Hooray a successful outing for the telescope - even then I had to wait about an hour for the sun to reappear - it disappeared the moment I went in for an EP originally this afternoon.

 

scopesun2sm.jpg

scope sun1sm.jpg

Solsm.jpg

Great stuff!! That's an excellent picture, the limb is nice and sharp and I don't think there was much on show today anyway.

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6 hours ago, Highburymark said:

As far as I could see, today was the most featureless Sun since I first started solar observing two years ago - it will get better

That sounds just about par for the course since I got into observing - the worst prolonged clouds in the last tens of years for both stars and sun and the moment I get the sun going even the sun goes quiet on me!  Maybe for the sake of the rest of you I should give up now! LOL

I must admit when I finally (it took me about 40 minutes of trying to find it) got the sun in the EP the family said 'Oh, its a bit err......plain orange disc isn't it?'  Hopefully, I will get the chance to see some sun activity later on - I suppose these marks last several hours when they occur?  I need to work on finishing a functional finder though I was pleased with my idea of taking out the EP which did help in finding it yesterday.  Hopefully some more pictures in the future with some spots.  I was pleased with the functionality of the filter though - it seemed to work well and I managed to see a nice orange disc just like those I've seen in some of the photos in the SGL threads.  At least it gives something else I can use the telescope for - perhaps if I am around I can watch the 4% eclipse later on in August using it.

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1 hour ago, JOC said:

I suppose these marks last several hours when they occur?

Active Regions generally last quite a long time, days or weeks. They move across the surface as the sun rotates, taking about 8 or 9 days to cross if I remember correctly. Most just make one pass, some come round again!

The sun is around its minimum activity at the moment, but there is still some activity every now and then. Just wait a few years and you may see a monster like this!

IMG_2465.JPG

IMG_2466.JPG

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12 hours ago, JOC said:

That sounds just about par for the course since I got into observing'Oh,

its a bit err......plain orange disc isn't it?'

Hopefully, I will get the chance to see some sun activity later on

Hehee :) par for the course ! I feel you pain !!

The good news is that the sun goes through cycles of activity,

the bad news is that they tend to be (usually ) about 11years long (give or take a year or so) and you have just missed the latest one, we are now a year or three into the down-slope, oh dear !

What is even worse news is that this latest cycle wot is just finishing (number 25 for ref) has had even lower activity than the previous cycle 11y ago, and that was even lower than,,, ! ,,,   all the other ones that I have been watching since the mid 50's,  that max. in 1957 was spectacular.

the other good news is that a few little spots will come to pass from time to time over the next wee while, and there may even be a big one some times.

If you really want to get depressed is that there is in some circles a comparison with other minor cycles that have (edit : may have, there is much statistical uncertainty still)  led to littleIceAges, so three cheers for global CO2 warming that may abate the ice age cycles, keep the home fires burning and lang may yer lum reek. :):)

Chin up,

Edited by SilverAstro
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I try ! :)

another interesting thing is that over all these cycles the big-wigs have assured us that they know what is going on - the sun has an 11y cycle (well actually a 22y approx if you account for the hemispherical magnetic inversion!)

but they dont, as shown by this slow decrease in active cycles and a split into a double peak, suspected in the last one 11y ago and now distinct in #25, leading to all sorts of speculations of subsidiary longer cycles, so our one-time nice stable and strong (!) sun is more of a variable star than previously thought.

sleep well  ;)

 

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