Solar

[Astro_hobbie]

Hello everyone, I quite fancy observing the sun but I’m unsure if my equipment is up for the job and if it is, what do I need to make it safe?

I have a Skywatcher 200p dobsonian with the standard 10mm & 25mm eye pieces and a Celestron X-Cel LX 7mm. I understand I’ll need a form of filter but the prices range from quiet cheap to rather expensive.  Will I need to cover the eye piece end and do I need an actual filter or will a solar sheet do?  

I have a budget between £50-£100 so will this give me something half decent? 

Many Thanks. 

[Giles_B]

Solar film over the aperture is what you need, in order to filter all the light before it hits your primary mirror - a sheet of film will fit within your budget. You can buy premade aperture filters, but this is probably a bit beyond your budget. Using some solar film and crafting your own filter is possible without too much effort - just make sure the film is well secured to the aperture. The film is extremely safe, but obviously if the film is poorly secured and slips ... your telescope, eyepiece and probably your eyesight (if you are at the eyepiece at the time) is at stake - so make sure you double check before each session, and you will overcome any risk. And DO make sure you point the aperture down at the end of the session - I almost smoked (literally) my 130mm reflector while packing up by carelessly removing the aperture filter while it was still taking some of the glare of the sun - luckily the smell of the cheap plastic focuser singeing was enough to alert me - but the lesson was well learned: the sun is a powerful energy source and needs to be treated with respect!

There is nothing you can safely do at the eyepiece end. You will find "solar filters" for screwing to eyepieces but these are NOT safe - this is especially true of a large newtonian like yours, as pointing it at the sun without an aperture filter will certainly crack the glass in the eyepiece filter, crack the eyepiece - assuming it hasn't fried your primary and secondary first.

You may also want to rig up a solar finder, or buy one - it can be surprisingly tricky to find the sun.

You will probably find that a 200mm reflector won't give the best views - the seeing during the day is poorer and the optimum is about 100mm of aperture or less. Ultimately a refractor is the way to go if you get more serious. However, solar film will give you a good taster of the joys of solar observation, so I'd really encourage giving it a spin!

Edited October 8, 2022 by Giles_B

[Giles_B]

"If you have a finder scope, remove it, or make a similar filter for the finder's objective as well."

Thanks to @Gfamily for reminding me of this important point in his answer to a another post about solar filters in the beginners forum today.

[wulfrun]

Your scope is plenty good enough. You need a filter over the front aperture of your scope, the eyepiece won't need one. Three choices, a ready-made one which is above your budget in that size. Or...make your own type with this:

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

Ideally, you'll need the larger, roll-size and make a full-aperture one (it comes with instruction how make a filter) but you could make a smaller one that isn't full-aperture or make a small one to fit over the off-axis cap if your scope front cap has one. You'd lose a bit of resolution versus full-aperture.

However you proceed, be sure to check, double-check and triple-check your work before aiming it at the sun, including making sure the filter is secure against wind or accidental knocks (use vecro, tape or whatever)...and don't forget to remove your finder-scope or make a filter for that as well.

EDIT: someone else's fingers were faster than mine @Giles_B

Edited October 8, 2022 by wulfrun

[Astro_hobbie]

Thank you all for the replies.  Now it makes sense to cover the aperture after your advise and it never occurred to me about removing the finder scope so thank you for that. 
 

Looks like the solar film is the way forward for me then. I do worry about how dangerous it can be so I will be double and triple checking everything before I observe. 
 

I know i will get hooked and will want a dedicated solar scope but I’ll just worry about that when it happens 😂

[PeterStudz]

@Astro_hobbie I enjoy observing the sun in white light and made a solar filter for my 200p Dob. I used a cardboard hat box and Baader film for a total coast of about £35. Details here…

 

[Astro_hobbie]

11 hours ago, PeterStudz said:

@Astro_hobbie I enjoy observing the sun in white light and made a solar filter for my 200p Dob. I used a cardboard hat box and Baader film for a total coast of about £35. Details here…

 

Excellent thank you for this, looks ideal

[RT65CB-SWL]

18 hours ago, Astro_hobbie said:

...I do worry about how dangerous it can be so I will be double and triple checking everything before I observe. 

Hi @Astro_hobbie and welcome to SGL.

What you said is so true. Every type of solar filter needs to double and triple checked before each and every use. If in doubt, don’t use it... bin it!

Edited October 9, 2022 by Philip R

[Moon-Monkey]

As said above the one thing in Solar is you only get two chances one for each eye !!! Double check then check again always hold your hand over the eyepiece to check before you place your eye anywhere near it cover your finder up and remember that unlike nighttime astronomy you may wnat to throw a sheet over your head as the ambient light coming onto your face is distracting I will only use BAADER planetarium sheets and make sure it’s the ND5.0 as ther is also an astrophotography one that’s not safe to use visually other than that be cautious and have fun solar is a great subject after all it’s the reason we’re all alive today 🙂