timwetherell

Thanks Jim

Thanks Mark Actually the objective housing is a snug push fit into the tube I had so wasn't any real need to thread - happily! I've made a few fine threads on my lathe but don't find them easy. If it were a loser fit I'd probably just have a grub screw to secure it. It is an the usual eccentric binocular cell but that only pushes it about 1mm off axis and for 7x magnification, I just didn't worry about it. Now have to think about mounting it somehow

Yep, exactly!

Wanted to create a time lapse of a Cepheid variable star for a talk I'm giving and thought Polaris was probably the easiest target. This is 4 frames at 24 hour intervals covering its 4 day period. It only varies by about 1/4 magnitude but I think the pulsing came out quite well in the movie

Starting to enjoy a bit of astrophotography with my Sony A7s but need to correct the drive during long exposures. Autoguider is of course the easiest solution, but I kinda like doing things the old fashioned way. I'm probably the last man alive still using setting circles! Anyway, trouble with manual guiding is that the thing you're photographing is almost never in exactly the same place as a decent guide star. Been thinking of all the ways to move the guide scope off axis, like classical three screw finder mount etc. Trouble is it's an 80mm guide scope so quite big and heavy and screws are very fiddly to use all the time. So decided it's probably easiest to move eyepiece instead. This is my home made rotate and slide stage that allows the eyepiece to be slid and locked anywhere over a 50mm image circle from the objective which amounts to about 5° of sky. I've incorporated a 2x barlow into the guide eyepiece so it has an effective focal length of about 6mm equating to 100x. Of course a CCD doesn't need that but eyeballs kinda do to get a decent level of precision. Still working on cosmetic improvements to the guidescope but the system seems to work well. now I need a clever solution to the problem of me leaving the guide illuminator on every time and wasting batteries. Current solution being to buy then in a 50 pack but that's not sustainable!

Will post some soon. Ultimate finish will be black but I need to work out the method of attachment to the main scope and machine up the necessary bits before any paint goes on

Thanks yes will take some more pics. It's part of an overall upgrade to my setup. I had a 66mm that wat serving as a guide scope and a finder and doing a poor job of both so moving on to a dedicated 80mm guide and 50mm finder. Will post more pics as it comes along

Much easier to buy one, but kinda fun to make a finder from an old binocular objective 5x 50mm with nice sharp 8.6° FoV

I'm inclined to agree. A nice buttery smooth well balanced alt-az is probably much easier to use than slow motion controls. You'd have to track both axis simultaneously at differing rates and it might be like patting your head and rubbing your stomach at the same time. I have a home made alt az for quite a big scope and it works quite well just pushing it around - bit more intuitive. Mine uses ball bearing races to take the actual load and separate discs and friction screws to vary the resistance which works quite well

Yes, every company and every nation will now no doubt want their own starlink and once the night sky is ruined anyway we'll probably end up with space advertising billboards!

The camera needs a real image on the CCD which should sit in space at a distance exactly equal to the focal length of the primary mirror. The eyepiece magnifies this real image and in effect turns it back into a virtual image at infinity. So the optical centre of the eyepiece will need to be beyond the primary mirror focus point by a distance equal to it's own focal length. Which in the case of say a 40mm, is quite a bit.

Had a set of Huygens eyepieces with my 60mm refractor as a kid. Bought a set of really cheap huygens EPs a few years ago for about £10 just for the amusement putting them in the 60mm finder to remind me what the views used to be like. Of course my equipment's better now but my eyesight isn't a sharp as it was back then!

Well done. yes, i think a 12" is probably the beast for the job. in my 7" I thought I saw something but wasn't able to navigate by those 14mag stars in a row by the supernova because I really couldn't see them. If it's gets to mag 12 or 13 then I'll definitely have another go visually

Nice shot, caught lots of detail in the spiral arms too!

Thought I'd seen it in the 7" but looking at my sketch it's possibly a bit low. In my photo the two foreground stars below look of similar magnitude so if you saw those too, you almost certainly bagged it! Might have another go tonight

Anyone been watching the supernova in M61? I think I could just see it visually in my 7" scope (possibly with averted imagination!) but shows up well in a 15s exposure

I'd stay up late or get up crazy early for something really special like a transit of Titan, but generally I'm a civilized hours astronomer. If it's clear between tea and my bed time i'll observe if not then I won't. The important thing is to do what makes you happy. Amateur astronomy is a hobby not a duty, so whatever makes you enjoy it most is the right approach. I have a friend who's happy to stay up all night imaging and that great for him, but for me 11pm is brandy and bed time

Thanks Dave. It was taken through a WO 66 ed apo. Camera was a sony a7s.

Actually that's not a bad idea! I might do that

It was very beautiful wasn't it! my preferred view was binoculars too, telescope was a bit too 'zoomed in'

Interesting idea I hadn't thought of doing that. Will give it a try

I've split it a couple of times in the UK with a 7" so you should be able to with an 8. It all comes down to atmosphere. When I lived in Australia and sirius was almost overhead the pup wasn't even really much a challenge with a 7", one could see it 90% of the time. Same with Antares, quite difficult in the UK which is a shame because it's one of the most beautiful doubles!

Miraculously we had clear skies last night and was able to see venus amongst the Pleiades for the first time in my life. Very cool, especially being able to see venus' half phase! Anyone else get any nice pics? I was hoping to capture some of the nebulosity but venus was so bright it swamped it.

2018 I believe, it's been raining here most of 2019 :D

Actually yes. it all came down to local sky quality. Even the slightest hint of haze will totally obscure them and we often have a very slight haze here. But on a particularly clear and haze free moonless night, they were relatively easy! So a bit like sirius B really, all seems to depend on seeing and transparency