The Sun 1 April 2013 white light

[Bizibilder]

The clouds finally cleared enough this afternoon to get these pictures of the Sun. A stack of 54/64 taken with a Canon 1100D and ED120APO stopped to 100mm, Baader Solar film. ISO 100, 1/2000sec. Stacked in Registax 5 and processed in PS CS5.

[Fogboundturtle]

What a monster solar spot AR1711 is. Just incredible. Well captured

[stargazerslivingroom]

Lovely and well presented, too. Could you explain/clarify the "stopped to 100mm"...Why and how is this done?

Thanks

Steve

[Bizibilder]

"Stopped" simply means that the diameter of the Baader film is 100mm rather than the full 120mm aparture of the scope. Thus I am, in effect, using a 100mm diameter scope - though the focal length is the same. So its a "100mm f/9 scope" rather than a 120mm f7.5. The only reason for that particular set-up is that i made my filter holder from a DIY store ventilation pipe fitting that conveniently slips over the dew cap of the scope, inconveniently it is a "step down" reducer which means I can only fit the 100mm filter.

As there is no advantage of using more than about 100mm aparture for the Sun the system suits me fine. (The aparture limit is due to the resolution of the image being governed by the "hot and sunny" atmosphere rather than the limiting resolution of the optics).

[stargazerslivingroom]

I'm obliged, Roger.

So much to learn....!

Steve

[Ewan]

Nice one Roger i am doing the same now as well.

[sologuitarist61]

Excellent!

[allcart]

Looks like I might be doing the same with my 120mm. it will be good to compare against the 100Rs.

You did well Roger. Keep up the good work.

[Steve Ward]

Great disc again Maestro . . .

[Montana]

Absolutely fabulous

Alexandra

[michael.h.f.wilkinson]

Great shot. Nice detail there. BTW, stopping down an achromat reduces chromatic aberration dramatically, so on scopes like an ST120 it works a treat. For ED scopes this is not really an issue