As mentioned in my previous post, I have the opportunity to buy a 20″ Dob from someone on the mainland. He transferred the optics to a permanently-mounted equatorial scope and now has the empty scope for sale. All being well, I am going to buy this from him and get a new mirror to fit it and the cost of the entire project should be less than ordering a brand-new, scratch-built custom scope. The original mirror was an f/3.7, so I am either going to have to get a 20″ f/3.7 mirror made, which will be slightly pricier than a standard f/4, or get an f/4 and alter the scope by adding longer truss poles, new secondary holder, changing the position of the attachment blocks, and so on, but by the time I’ve done all that, I may as well spend the extra couple of hundred quid on an f/3.7.
I’ll need a Paracorr as the coma will be bad with such a fast mirror, but I can live with that, it’ll be worth it to have large aperture! But, we’re getting ahead of ourselves – the one item of bad news is that I have to save up first. It’ll take me about three months to save for the scope and then at least 8 to save for a mirror so this won’t be up and running for the best part of a year yet, unless I get lucky in the wallet department. But…how exciting! I’ve wanted a large scope ever since I became a deep sky observer the best part of 20 years ago, so this will be an ambition come true.

I’m planning to spend the weekend putting the finishing touches to the shed. Then I need to put the castors on my 12″ scope’s base so I can roll it in and out then we’re in business!

There’s no sign of the weather clearing up. It’s typical unsettled English summer weather. I hope it clears up in August, so I can catch the Sagittarius and Ophiuchus summer goodies before they vanish into the twilight.

Oh, and I got my monitor back on Monday. Only it’s not my monitor, it’s a replacement, which is good as it’s a brand-new machine and unlikely to go wrong – I hope. At least PC World eventually got it sorted for me after first trying to fob me off with this ‘You have a contract with the manufacturer, not us’ crap – they need to read the Sale of Goods Act, especially this bit. Stuff less than a year old should not break, but it does occasionally and the retailer has a responsibility, under the Act, to refund, repair or replace the item and not give the customer the flick with some stupid excuse about ‘extended warranties’.
The sketches, I am pleased to say, look fine.