I’ve had a bit of an upgrade on the Solar scope front. Despite the 150mm aperture the 80mm glass solar filter was stopping the scope to the point, where any magnification above 50X turned the view to a blurry mush. With my current selection eyepieces, I was only able to use some pretty horrible – and very old- Meade 4000 series Plossls in the 26mm to 40mm range.
The most obvious way to see if this could be improved would have been to fit a full 150mm aperture solar filter. One of these in metal coated glass was going to cost a wedge, so the next best thing was to fit the 80mm filter to my TMB 80 APO refractor and give that a wizz.
The views have been transformed. The shorter focal length means I can use all three of my Televue Delos eyepieces, which give me a magnification range of between 34X and 80X. Everything just looks so much crisper and with more contrast.
I forgot to mention in a previous post is the addition of my new solar finder. The design was taken from Thingyverse and printed on my fairly new Flashforge Adventurer 4 3D printer. The base has a standard Viven dovetail which initially fitted into the finderscope socket on my 150mm RC. Not having one on the TMB,
I simply drilled a couple of matching holes in the base, which allowed it to fit on the scope mount ring of the TMB. To mark the initial alignment, just place the solar disc in the centre of the eyepiece and then mark over the projected dot of the Sun on the rear screen of the finder. No more faffing looking at the scopes shadow on the ground and trying to figure out when you’ve hit minimal size that should indicate you are on target. If something ever moves. Just wipe of the dot you made ad repeat the alignment. Simples.
On the book front, I have just acquired this published by Axilone Publishing. This tome is a collaboration of over a dozen experts in their field and is is what I can only describe as ‘Fully Comprehensive’ in its coverage. Apart from a couple from the Springer stable, there don’t appear to be many books specifically on Solar observing. First printed in 2021, it’s also completely up to date and up with current observing techniques and is probably the only book around that is worth having on your bookshelf. Maybe a little pricey at 69 Euros compared with what’s out there already, but bite the bullet and get yourself a copy.
One thing to come out of reading this book is that they don’t rate metal coated glass solar filters unless they happen to be made by Zeiss or Lichterknecker. It looks like, for once, that the low cost Baader Solar film and a Continuum filter combination, rule the roost when it comes to visual observing, so it looks like my Meade glass filter will have to go.
I’m currently 3D printing a cap that will take some 5ND Baader film that I now have. This whole assembly will be a tight slide fit over the dew shield of the TMB. Watch this space.