The Sun through a telescope

[Sierra Golf Mike]

I know not to lookthrough a telescope at the sun, so how do I view the image and how are the images taken?

Regards

Steve

[Andrew*]

There are a few ways to view the sun, but the safest is to use a filter that covers the entire objective lens and blocks out most of the light.

The cheap way is to block it off by intensity - just dim it down. This is called "white light". You can make your own filters from special film, or there are custom glass ones: Solar Filters

White light will show some granulation and sunspots.

The expensive way is to block it off by wavelength, so you just see one specific colour. This method shows more surface detail, as well as prominences. There are two "flavours": the more common Hydrogen alpha (which is red light), and Calcium K (violet). These telescopes are very delicate, precise instruments and cost over £500 for a basic model, but the detail is amazing.

HTH

Andrew

[LukeSkywatcher]

Another way is to project the image of the Sun through the telescope onto a white surface. This is called Solar Projection. BUT to be honest i dont think this is a very good or SAFE way to do it because to aim your scope at the Sun in able to project its image you need to be able to see the Sun through the scope or finder...............which involves staring at the sun through the scope................................which as said should only be done with proper filters etc.................so you will need a filter even to do solar projection.

[yeti monster]

If you set a projection screen behind the finder, you can align using that. Or use the shadow cast by the scope against a wall, or the floor, if viewing whist the sun is high. If using a newt, have the focuser aimed down towards a screen mounted low, to reduce the possiblity of any nasty accidents from the intensified sunlight.

[LukeSkywatcher]

If you set a projection screen behind the finder, you can align using that. Or use the shadow cast by the scope against a wall, or the floor, if viewing whist the sun is high. If using a newt, have the focuser aimed down towards a screen mounted low, to reduce the possiblity of any nasty accidents from the intensified sunlight.

Yes this is ALL true but dont you think that trying to aim a scope at the Sun while not directly looking throgh it or a finderscope is like trying to find a needle in a haystack.

In saying that.......................

I have spent about 20 mins on a clear sunny day trying to find the Sun while looking directly through the scope which had a solar filter on the objective end.

It then dawned on me that i should have just used my RDF to locate the Sun as the RDF has zero magnification.

Live and learn.

[yeti monster]

That's how I aim on the sun, project the finder onto the palm of my hand (not focused, or that would hurt), with the filter already on the scope and a wide field EP. After a couple of attempts, it soon becomes easy.

To watch the setting sun this evening I used the long shadow cast across the front yard, and that wasn't far out. A couple of sun spots, although atmospherics meant that I couldn't resolve then at high mags.

[LukeSkywatcher]

Maybe trying to locate the sun through my scope is worse because my scope is on an undriven/non-Go-To EQ mount so i have to manually track it (to find it) using the RA knob which is SLOW.

I know now that using the RDF is an easy solution. BUT i no longer use that scope.

[yeti monster]

My 114, which is the one I use for solar, is manual EQ, just slacked off the clamps enough to be able to "push-to", then after nipping up the screws, make the final alignment with the slow motions, takes but moments. Once you have your target, it should be easy enough to keep in view.

[LukeSkywatcher]

My 114, which is the one I use for solar, is manual EQ, just slacked off the clamps enough to be able to "push-to", then after nipping up the screws, make the final alignment with the slow motions, takes but moments. Once you have your target, it should be easy enough to keep in view.

I'm sure thats the way to do it. I just had not used my scope and EQ mount much to even think about slacking off the clamps.

Life was so much easier when all i used was binoculars.

[Talitha]

The easiest and fastest way i've found of making sure the Sun is in my fov is to aim the scope without looking through an eyepiece or finder.

After placing the solar filter on, i merely look at the shadowlines on the scope itself. When the shadows and lightfall are evenly distributed on the outside of the OTA, i'm all centered.. works every time.

[Astro_Baby]

Never done it but have seen it aligned as Talitha suggests. ie watch the shadow falling on the ground from the scope. When the shadow is at its smallest your aimed bang on.

You can also do it with a nail stuck to the outside of the scope tube with something like blue tack.

Make sure you cover the finder when doing the sun route. Dont know about these days but I was told never to use a reflector for solar as the heat coming up the tube onto the secondary mirror can heat the secondary up with possibly nasty results.

[stev74]

All the different ways to observe the sun are talked about and shown with scopes on this months Sky at Night programme. It's well worth a watch and answers all the questions in this thread. Including how to align your scope on to the Sun using it's shadow as Astro_Baby and Talitha describe.

BBC iPlayer - The Sky at Night: The Sun in Splendour

Edit - The iPlayer is only viewable in the UK. I think the episode will also be included on the S@N magazine's CD next month. So if you can't access the programme through the iPlayer maybe you can get the magazine.

Cheers

[brianb]

The easiest and fastest way i've found of making sure the Sun is in my fov is to aim the scope without looking through an eyepiece or finder.

After placing the solar filter on, i merely look at the shadowlines on the scope itself. When the shadows and lightfall are evenly distributed on the outside of the OTA, i'm all centered.. works every time.

Yes, that method works very well ... but the dedicated solar finders that come with solar scopes are better still. As they're essentially pinhole cameras, a self build version of the Televue Solsearcher is very feasible, and would save a few pounds ... not that the TV version is extortionately expensive.

The thing you must do with a conventional finder when observing the Sun is either not to fit it, or to leave it capped, or to have a safe solar film filter fitted to it as well as the main scope.

As for projection - OK for refractors up to about 3" provided you're using a Huyghenian or Ramsden eyepiece made from solid glass & brass. All other equipment combinations, your eye may be safe but the equipment isn't - plastic will melt or burn, cemented components will craze, glue will melt and secondary mirrors will crack.

Solar film - used according to the instructions - is safe for your eyes and for your scope. It gives a better image than projection, too.

[skywatcher2]

Meade ETX LS 6" ACF Telescope

just baught this this afternoon and i was absalutaly amazed at the quality what do u think guys john

[yeti monster]

I know that you're excited, but NO NEED TO SHOUT!

[Andrew*]

I didn't want to mention solar projection, because there are so many pitfalls, and it is far from the safest method. White light using a film filter is much safer, and allows you to increase magnification, and is cheap.

Andrew