Solar observing with classic refracting telescopes
Posted 12 February 2013 - 03:49 PM
Posted 12 February 2013 - 04:02 PM
Posted 12 February 2013 - 04:06 PM
Posted 12 February 2013 - 04:20 PM
Posted 12 February 2013 - 04:24 PM
Auxiliary filters with the wedge were a B+W N.D. 3.0 and a single Celestron (Japan) polarizing filter.
Posted 12 February 2013 - 04:29 PM
At last year's Stellafane Bart Fried was using a Brashear hershel wedge on his 4" alt-az Brashear and getting great images, but white light obviously. So the next day I took out MY Brashear hershel wedge that I'd been afraid to use (somehow I thought its age would be an issue) and used it on my 4" Clark. Lots of fun. Very nice white light images. Adding H-a increases the pleasure immensely!
Posted 12 February 2013 - 04:37 PM
I love wedges. I have the Intes and the Lunt. I love the Intes as it has no additional filters built in, only the wedge so its very flexible for work with specialized Ca, Na, Fe, and H-a filters. The Lunt is nice because the N.D. 3.0 is built in so no worrys; it is wonderful with the Baader continuum filter.
Posted 12 February 2013 - 04:38 PM
Posted 12 February 2013 - 04:40 PM
And spring is still two months away.
Posted 12 February 2013 - 04:42 PM
Posted 12 February 2013 - 04:47 PM
The general rule of thumb for daytime seeing is 25 to 30X per inch aperture.
With my Herschel wedge or objective filter, I prefer much lower magnifications, generally. 10x - 20x per inch seems to work fine for me here. Only rarely do I use higher and then the seeing must be excellent.
With my projection box on my 85mm Zeiss apochromat, I generally used much higher magnifications. 177x - 400x was normal. Occasionally, if the seeing was excellent and there was some interesting action going on, I would use 800x. I sometimes saw extraordinary details.
Posted 12 February 2013 - 04:48 PM
Posted 12 February 2013 - 04:51 PM
Posted 12 February 2013 - 04:55 PM
Springtime comes early here in the Upper South. I am very thankful for that. Nearly three months with little to no observing and I was going stir crazy. It has been either cold or cloudy since Thanksgiving here. I think the last day I did any substantial solar observing until last week was Thanksgiving Day on Nov 23 while the turkey was baking in the oven. I hope spring and clear skies come early for you too.
Posted 12 February 2013 - 04:59 PM
Posted 12 February 2013 - 05:09 PM
I never was a big fan of open solar projection screens other than for educational purposes. The projection box I've made for my 85mm Zeiss is closed on all sides, save for a small viewing aperture in one side, where you can look at the screen. This boosts contrast phenomenally and allow very high magnifications to be used, resulting in some amazing images. Faculae are extremely spectacular with this setup.
One side of the box can be opened to allow changing eyepieces. It was otherwise a very unassuming cardboard box, not very pretty at all. It was meant to be a prototype, just to see if it worked, but it worked so well, I never did get around to make a more finished version.
C'est la vie.
Posted 12 February 2013 - 07:12 PM
Posted 12 February 2013 - 07:42 PM
Remember to use a Huygens or Ramsden for projection. I melted and bubbled the balsam in a shiny new 25mm VT ortho with my 6" F8 back in about 77 or so. Sucked since I save d up to buy that eyepiece.
Posted 12 February 2013 - 08:50 PM
Posted 13 February 2013 - 03:54 AM
Old 0.965 Japanese all metal barlows also work as they are single element, no cement.
Are you sure? I've never seen a single element barlow. Wouldn't that cause terrible color error?
Posted 13 February 2013 - 06:32 AM
Very nice. Thank you for posting all this. I am having an adaptor made to fit my 60mm double-stacked (0.5A) Coronado etalon to the front cell of my 75mm Polarex. It should be ready within the next couple of weeks - just in time for the sun to start clearing the roof of my house at all daylight hours...!
I use a Baader Herschel wedge also but plan to keep it attached to my 6" AP instead of the Polarex. I'm very much looking forward to the native f/20 solar views on the Polarex!! Imagine adding a barlow to that...let's not get too excited there's the seeing to take into account...
Posted 13 February 2013 - 11:38 AM