Solar Filters

[MeatyFish]

Hi, I have Celestron 20x80 binocolaurs and would like to get some solar filters to observe the sun. Any advice? I am a bit hesitant (with or without filters) to observe the sun, but believe that it would be very interesting. Any suggestions/warnings/etc?

[nephilim]

Personally, I wouldnt like to recommend ANY, I view the sun using Baader solar film over the full aperture of my scope ( A reflector), it eliminates the risk of glancing even slightly at the sun as i'm looking thru my scope at a different angle to the position of it, even with filters on a pair of bino's there's always the chance they may slip slightly & damage your eyes for good!! Thats only my opinion but as I say, I wouldnt risk it.

[KenG]

I bought a solar filter for my etx from Telescope House. They come in a range of sizes and are reasonably priced. Have to say that I enjoy viewing the sun via this, and that friends, whilst initially incredulous that they can actually look at the sun, are gob-smacked by the views of sun-spots.

[MeatyFish]

I kind of understand what you mean, why is something like this inappropriate or carry risks (they claim to be full aperature)?

http://www.telescope.com/Binoculars/Binocular-Accessories/Orion-Solar-Filter-Sets-for-Binoculars/c/5/sc/75/e/23.uts

[MeatyFish]

I bought a solar filter for my etx from Telescope House. They come in a range of sizes and are reasonably priced. Have to say that I enjoy viewing the sun via this, and that friends, whilst initially incredulous that they can actually look at the sun, are gob-smacked by the views of sun-spots.

Aye, that's for a scope. Do you know what the filters are like for binoculaurs?

[scoobee]

If you don't fancy making your own, could try these:

http://www.scsastro.co.uk/catalogue/solar-filters-for-binoculars.htm

A tad pricey, but how much is your eyesight worth

[Qualia]

Would there be any reason in not wanting to get hold of a cheap secondhand refractor at UK Astronomy with an aperture of around 80mm to 100mm? You can pick one up for under £100 with ease. Then I'd set about making myself a sun filter with the Baader Solar film and hunt out a cheap EP which would give me a magnification of about 50x understanding that I'd get a nice white-light set up for under £150 which could double as a decent Lunar and Planet and star field scope in the evening.

[nephilim]

I kind of understand what you mean, why is something like this inappropriate or carry risks (they claim to be full aperature)?

http://www.telescope.../sc/75/e/23.uts

I wouldnt say they're not safe when used properly or doubting someones ability to observe the sun safely, the only reason I'd be put off solar viewing with binos is that ur looking directly at the sun, yes the filters will protect ur eyes fine but there's also a slight chance that they may slip (the binos not filters) u may move inadvertantly etc and all it takes is a quick glance to do some really serious damage. It may seem i'm been a bit of a health and safety nut but I've seen photos of eyes damaged by the sun & its not a pretty sight & even worse for the person it happens to.

[brantuk]

I agree with Nephilim - with viewing the sun you need to be 100% sure you aren't going to have a mishap and accidentally catch a glimpse of the sun straight through a lens. It only takes a split second to damage your eyes beyond repair and become blind. Also Baader solar film needs checking for pin holes every time you use it. A mounted scope on a windless day with that kind of filter is much safer - it's not worth the risk. The only alternative is to get purpose made bins with full sun filters built in - or better still - a proper solar scope.

[Bizibilder]

I would agree with the above - Solar observing with binoculars is potentially dangerous - even with the proper filters. Much better to get a small refractor and a Baader filter - the refractor should be equiped with a diagonal so that you are looking "across" the instrument and cannot look at the Sun directly.

Personally I have a simple rule never to observe the Sun even with the correct filters - I only ever take photographs and do all my alignment and focussing on my computer screen. My eyes are too valuable to ruin in a split seconds' mistake. Yes - a fraction of a second is enough to produce total blindness.

[MeatyFish]

Thanks, but I am still not sure why the Orion solar filters are considered risky (or, rather, more risky than a scope).

I agree with Nephilim - with viewing the sun you need to be 100% sure you aren't going to have a mishap and accidentally catch a glimpse of the sun straight through a lens. It only takes a split second to damage your eyes beyond repair and become blind. Also Baader solar film needs checking for pin holes every time you use it. A mounted scope on a windless day with that kind of filter is much safer - it's not worth the risk. The only alternative is to get purpose made bins with full sun filters built in - or better still - a proper solar scope.

I suspect the risks attached to using an affordable solar scope are similar to using solar filters. I guess the sun is something I will not be able to observe.

[Qualia]

Personally I have a simple rule never to observe the Sun even with the correct filters...Yes - a fraction of a second is enough to produce total blindness.

Do you think, or do others feel that I am being a fool observing the Sun each morning in white-light? This is not a rhetorical question but an honest enquiry. Do you guys feel I should give up on this pleasure or try to get myself kitted with a Herschel Wedge before doing anything else?

Sorry to disrail the thread, but it does seem pertinent to its general drift.

[brantuk]

Well for a start - the one in the link above is very flimsy - you need to be sure it's attached right and won't come of whilst using bins. It needs to be meticulously inspected each time for any pinhole ingress and it would blow off in a stiff breeze. I have one on a refractor and I'm very careful with it making sure it's attached firmly and it's a calm day. I'd be more comfy if it came with metal rather than plastic screw holders.

With a solar scope you get a properly coated and filtered objective screwed onto the ota and a purpose made etalon inside the scope. Not had any probs with mine so far. I guess it depends on budget but you can get a PST for around £500 new or a bit less s/h - by far the safer option imho.

Edit - I think it's more to do with the potential for a filter on bins to drop off or get knocked off Quaila. I'm uneasy with my white light set up for that reason - I'm on it like a hawk when I have folks around me lol. The film itself is safe.

[MeatyFish]

Well for a start - the one in the link above is very flimsy - you need to be sure it's attached right and won't come of whilst using bins. It needs to be meticulously inspected each time for any pinhole ingress and it would blow off in a stiff breeze. I have one on a refractor and I'm very careful with it making sure it's attached firmly and it's a calm day. I'd be more comfy if it came with metal rather than plastic screw holders.

This is what I was asking about. In what way are they flimsy? Those are pretty expensive (over £100), which is why I asked. They are as safe as they get.

With a solar scope you get a properly coated and filtered objective screwed onto the ota and a purpose made etalon inside the scope. Not had any probs with mine so far. I guess it depends on budget but you can get a PST for around £500 new or a bit less s/h - by far the safer option imho.

Only £500?

[brantuk]

Yeah - it's the nylon (not plastic) screws I was refering to. One hundred dollars - what's that in English these days - around eighty quid? So say forty quid each - sounds around the right ballpark - my single filter from FLO was about £35 as I recall:

http://www.firstligh...lar-filter.html

They also do the Baader film on its own - a lot cheaper - I think it's under £15 per sheet - fix on with a strong elastic band or sticky tape.

Nope it's gone up: http://www.firstlightoptics.com/solar-filters/baader-astrosolar-safety-film-nd-50.html

"Only £500?"

Yeah - solar scopes aren't cheap - I daren't tell you what mine cost but you can google it if you want lol

[KenG]

The Orion filter that I use is a VERY tight fit on the scope - it's a wrestling match getting it on and off - and the nylon screws are surplus to requirements. There is absolutely no possibility of it ever becoming accidentally detached. The views I'm getting are quite wonderful and doubters should consider the fact that an American Company (Orion) is not going to market solar filters unless they are 110% safe. The possibilities of lawsuites in the event of failure are just too great.

[MeatyFish]

Yeah - solar scopes aren't cheap - I daren't tell you what mine cost but you can google it if you want lol

Hahaha... I have a fair idea how much you are looking at (... and the views of the sun you get in the morning).

The Orion filter that I use is a VERY tight fit on the scope - it's a wrestling match getting it on and off - and the nylon screws are surplus to requirements. There is absolutely no possibility of it ever becoming accidentally detached. The views I'm getting are quite wonderful and doubters should consider the fact that an American Company (Orion) is not going to market solar filters unless they are 110% safe. The possibilities of lawsuites in the event of failure are just too great.

I wish you did not say that. That makes me really tempted to grab some.

[BinocularSky]

I use Baader Astro-Solar film on my 10x50 binocular. Used properly, it is safe (if it wasn't, people like FLO would not sell it). "Properly" means thoroughly checking them every time for pinholes (the main cause of photochemical retinopathy) and taping them onto the binocular so that they cannot be accidentally dislodged. Only use them on the "big end" and only use them exactly in accordance with the manufacturer's instructions. However, as they say, "Nothing is completely foolproof to a sufficiently determined fool," so, unless you are confident that you can use them safely, the best advice is not to use them.

FWIW I have a YouTube video on safe solar observing (including binoculars) at:

[LukeSkywatcher]

Ive read all of this thread and maybe i am blind (no pun intended) as to how observing the Sun with bins and the proper filters, is any more dangerous then observing the Sun with the proper filters and a telescope.

The OP has bins of 80mm aperture. You can buy ready-made solar filters for 80mm scopes or you can make your own using solar film. You can use the same ready-made filters on bins as are sold for scopes...............just as you can make your own 80mm filters for bins or scopes.

I cant see how either solution is more risky just because you are observing with bins.

A tight fit is a tight fit, no matter if on the end of a scope or on a set of bins.

My only concern with observing the Sun with 20X bins is that you might not have enough magnification to see sunspots.

I'd hate my ignorance on this matter to lead to anyone having their eyes damaged by solar observing with bins, so i will "tow the party line" and say that any solar observing i have done has been done using the Baader Solar Film "full aperture" and a scope.

A few weeks ago i bought a new sheet of the film from FLO and as yet i have not made a new filter. I plan to use it on a small 70mm refractor and am unsure if to construct a full aperture filter or just go with a "dust cap" peephole filter. The full aperture filter is probably safer then simply taping a small square of the solar film to the inside of my scopes dust cap.

I'm useless at these "Blue Peter" type projects, so that is why i am holding off making the filter. Not to mention the fact that i cant remember the last time i actually saw the Sun. I think i'll wait til Spring to build it.

[Bizibilder]

The point that has been made is that looking along a refractor or binoculars (ie in the conventional way) can lead to the observer getting an eyeful of Sun. As I posted earlier you should use a diagonal with a conventional refractor so that you look across the instrument and thus cannot "slip" into the full glare of the Sun.

[LukeSkywatcher]

The point that has been made is that looking along a refractor or binoculars (ie in the conventional way) can lead to the observer getting an eyeful of Sun. As I posted earlier you should use a diagonal with a conventional refractor so that you look across the instrument and thus cannot "slip" into the full glare of the Sun.

I see what you are saying Roger (i think), but a diagonal in a scope acts in exactly the same way as a prism mirror in bins. Its all reflected sunlight. You are never looking directly "through" a train of optics..........but across. This is still uuber dangerous.

Dont get me wrong........................reflected light in a scope or bins is just as dangerous. If you are saying that it is NOT a good idea to observe the Sun through a scope without using a diagonal.......................I completely agree for two reasons:

1/The scope will most likely not focus

and (more importantly)

2/ The heat and UV light from the Sun will be more concentrated and will more likely then not blind you foerever.

All i am saying is that i think observing the Sun with bins or a scope (and the proper filters), carry the same risk.

[MeatyFish]

Thanks for all your advice on this.

I will probably hold off buying anything, and maybe only pursue this type of observation if i get interested in astrophotography.

Luke Skywatcher has probably sealed the deal, I think that observing sunspots would be a clincher, and this might not be possible with a 20X magnification.

[Qualia]

Ay, to get the most pleasure I have found 50x to be the general, everyday sweet spot with the 4" f/10. Of course, for close up sketches I might take it up to 100x and for measurements I do sometimes go as far as 150x but the umbra and penumbra at that mag are just blobs.

[LukeSkywatcher]

Thanks for all your advice on this.

I will probably hold off buying anything, and maybe only pursue this type of observation if i get interested in astrophotography.

Luke Skywatcher has probably sealed the deal, I think that observing sunspots would be a clincher, and this might not be possible with a 20X magnification.

Buying two ready-made solar filters for a set of 20x80 bins is gonna be expensive and might not deliver.

As other have said..................a small refractor (Celestron Travelscope 70...........costing about £100) and a sheet of Baader Solar Film is a much cheaper and rewarding way to go.

The Travelscope70 also gives great widefield views at night of the universe and comes in a small backpack that can be brought on flights as hand luggage.

I just dont feel 20x will deliver. Think of it this way:

Both the Sun and the full Moon appear to be the same size in our sky. With 20x bins you can see craters on the Moon but not very up close (i have a set of 20x90 bins, so i know). Imagine trying to see a Sun spot with 20x80 bins on the Sun, that is 400 times further away from Earth then the Moon is.

Thats why i think 20x for Solar observing wont be possible.

[Bizibilder]

Just to clarify: My suggestion of looking "across" the instrument (by using a diagonal) simply means that if you take your eye away from the eyepiece you are NOT looking directly at the Sun (you are most probably looking at the ground!). Without the diagonal (ie with the scope set up "straight through") as soon as you move your eye away you most certainly ARE looking directly at the Sun.