sun filter

[Crossway]

There was reference to sun filters in a reply to my previous thread of yesterday.

Having always been very aware of the hazards of sun damage to ones eyes , through my time as deck / navigation officer in the merchant navy ( Sextant usage) I have never had any interest in direct solar observation with telescopes or binos.  HOWEVER  could I ask if there is any Perfectly Safe filter which can be home made.  I think I know what the answer might be !

Pete

[PeterCPC]

https://www.firstlightoptics.com/solar-filters/baader-astrosolar-safety-film-nd-50.html

Peter

[rwilkey]

Hi Pete, you might find this webpage useful: https://astrosolar.com/en/information/how-to/how-to-make-your-own-objective-solar-filter-for-your-camera-or-telescope/

Myself, I preferred to buy the ready made ones as in my mind they attach and fit better, and are not all that expensive:

[John]

Good advice above.

The most important thing is that your scope aperture should be fully covered either by the filter or the frame holding it and that there should be no way at all for the filter to fall or be knocked off your scope while you are viewing.

 

[scotttumsh]

i made this filter for my Evostar 120, made with plywood and Baader solar film nd50.

Scott

[Crossway]

Thank you everyone for very useful replies and 0bviously the Baader solar film is a  thoroughly  well tried and safe answer .   The examples mentioned seemed to refer to refractor scopes ,  perhaps a bit dense of me but I assume the same treatment applies to reflectors.

Pete 

[rwilkey]

16 minutes ago, Crossway said:

Thank you everyone for very useful replies and 0bviously the Baader solar film is a  thoroughly  well tried and safe answer .   The examples mentioned seemed to refer to refractor scopes ,  perhaps a bit dense of me but I assume the same treatment applies to reflectors.

Pete 

Hi Pete, yes, the same applies to reflector scopes, but you usually have to get/make bigger ones, and as John mentions make sure they fit securely.  I also check for damage, pinprick holes and that sort of thing before I use it just to be absolutely safe. 

[scotttumsh]

Yes pretty much exact same although reflectors tend to be much bigger apertures so solar film would have to be bigger sheet size. very easy to make you own. give it a go, just be sure not to damage the film however, good way to check is to hold the filter up to the sun with the naked eye check for tiny holes. all the best.

Scott

[John]

You don't have to make use of the full aperture for solar viewing so you can make an off axis solar filter by using the aperture that is built into the scope dust cover, eg: the Skywatcher / Celestron type:

[Crossway]

Helpful replies and thanks everyone.  Will enjoy getting started on my next project and have taken serious note of  warnings about treatment and care of these filters.

There was a thread in SGL just a few days ago about the on going absence of clear night skies .........here in the North East it seems to be permanent .  Murky days  are in high figures as well so hopefully a new sun filter will  attract some good luck!!

Pete

[Louis D]

I've been using the Baader Solar Film in a couple of homemade filter cells for almost 20 years to good effect.  I'm thinking about trying the Thousand Oaks Optical filter after having used their solar eclipse glasses to good effect in 2017.  I find BSF a bit bright for my taste and tend to add a neutral density (moon) filter to bring down the brightness a bit when not taking photos through the scope.  When I was younger, the brightness didn't bother me.  I also used to drive in bright daylight without sunglasses, but not anymore. 

[George Gearless]

When I was a kid, we used a piece of clear glass and sooted it with a candle so we could look at the sun.

Not a treatment I'd recommend for your binocular lenses :). Not to mention that it's probably still highly unsafe and might still burn your eyeballs to boiling point.

[Alan64]

One aspect of which merry mention has not been made: Do not stretch the film at all when making your own.  It should just lay loosely within its frame.  A wrinkled appearance is perfectly normal, and expected.  If you stretch the film, the images will be less sharp.

[cletrac1922]

On ‎06‎/‎02‎/‎2019 at 22:46, John said:

You don't have to make use of the full aperture for solar viewing so you can make an off axis solar filter by using the aperture that is built into the scope dust cover, eg: the Skywatcher / Celestron type:

Done same thing with my 10" dob, using Baade visual film 

Attached pic taken with mobile camera to eyepiece

Solar eclipse 2012, where I was, only had 80% eclipse

Used a glass filter on my ED80, prior to purchasing Colorado Solarmax

  

 

 

 

[Demonperformer]

Good advice given. Rule of thumb ... think what can possibly go wrong and assume it will unless you mitigate against it.

One thing that hasn't been spelt-out, possibly not necessary for OP, but in case this thread gets picked up on a google search ... the "solar filters" that come with department store scopes - the plastic things you screw into the eyepiece - there is only one safe thing to do with these: Find a solid surface, place them on it and hit them hard with a heavy object until they are dust ... they take the full force of the magnified heat from the sun and the constant expansion/contraction will eventually cause them to shatter. This will probably happen while in use and the retina will be burnt out instantly. THESE THINGS ARE DANGEROUS.

[Pete Presland]

12 minutes ago, Demonperformer said:

Good advice given. Rule of thumb ... think what can possibly go wrong and assume it will unless you mitigate against it.

One thing that hasn't been spelt-out, possibly not necessary for OP, but in case this thread gets picked up on a google search ... the "solar filters" that come with department store scopes - the plastic things you screw into the eyepiece - there is only one safe thing to do with these: Find a solid surface, place them on it and hit them hard with a heavy object until they are dust ... they take the full force of the magnified heat from the sun and the constant expansion/contraction will eventually cause them to shatter. This will probably happen while in use and the retina will be burnt out instantly. THESE THINGS ARE DANGEROUS.

Still see these sold on Ebay, despite reporting everyone I see, disgraceful attitude by such a large company. 

[Merlin66]

Many of us on numerous occasions have pointed out the unsafe nature of these filters....and still they continue.

[SIDO]

I think what's awesome about buildng your own solar film cells besides being even more inexpensive is one can also craft a filter cell for his or her magnified finder, on a RACI finder like the ones I use that will provide an angled view away from Sun and this works very well.

For a red dot type finder one can shadow align to the sun by slimming the finder and telescopes shadow on the ground, for me I like this method best as I don't even have to look towards the light at all and a pair of sunglasses are also worn so when the Sun is found I am at that time experiencing zero light blindness wich makes the whole experience more pleasing when I get to the eyepiece.

Purposed solar finders are also available.

         Best of Luck Everyone ?

                         Freddie...

[John]

Good advice about finders Freddie - it's easy to forget to filter or cover the optical ones !

[S.A.M]

Hi Pete,

When using a Baader filter, you must check it every time for damage.  If there is a pin prick hole, the filter MUST be destroyed or you could lose an eye when viewing.

Happy times ahead viewing the Sun.  If you can view it with a Ha scope so much the better, it will blow your socks off?

Peter 

[Merlin66]

Peter,

Based on my twenty odd years of solar observing and the extensive use of the Baader solar film, it's most unusual to get pinholes - the material is coated on both sides so the pinhole would have to be on both and align.

(I keep my filters in a dust proof container when not in use)

If a pinhole is found, it's not the end of the world. The increase in light reduces contrast and causes glare, certainly not a cause of eye damage. The pinhole can be covered by Typex or black marking pen - and life continues.

It's of more concern to always have the filter securely fastened to the scope. Check, check again then do a final check.......

 

[JOC]

I think the thread above is purpose made for the OP