Which Nebula Filter?

[John]

John,I have an adapter that may work,but wanted to ask you how the focusers are different?It looks as they use an extra adapter to use 2" eye pieces,so if this adapter accepts the 2" eyepieces,can there be any other issue preventing a 2"-1.25" adapter from working?(other than eyepiece base hitting filter)

If you put a 2" - 1.25" adapter into the Skywatcher 2" adapter you will find that 1.25" eyepieces will struggle to reach focus. I've seen this happen many times to newcomers to these scopes where they, quite logically, use both the supplied 1.25" and 2" adapters at the same time instead of separately, as they need to be used.

I'm not sure there is an easy solution to this. It would be great if there was though

The adapters in Gerry's post are a different design to the Skywatcher ones. Skywatcher are different in this respect to all other brands I think, apart from some Celestron and Orion (USA) scopes which are made by the same people who make Skywatchers.

Further edit: Gerry's suggestion of removing the 2" adapter and then putting the new one that will take 2" filters straight into the drawtube is completely sensible except that the Skywatcher drawtube top is not exactly 2" - it's a bit more than that and designed to take the flange that is on the bottom end of both the SW 2" and 1.25" adapters. Why they have gone for this design is beyond me but's it's been this way on their standard single speed focusers for years.

[AlexB67]

Sorry didn't men the hijack the thread but asking questions is never a bad thing, I guess it makes for interesting conversation. Some may also find this useful, at least it clarified some things for me having had a browse elsewhere and also discussing the merits of the various filters.

[jetstream]

What is the outside diameter of the stock Skywatcher 2" I.D. adapter?

[John]

What is the outside diameter of the stock Skywatcher 2" I.D. adapter?

It depends where you measure it as it tapers. It's 57mm or just a fraction under at it's widest as that is the inside diameter of the receptacle on the end of the drawtube it has to fit into.

[jetstream]

John,does it have stepped portion for the flange?If it is stepped what is the O.D. below the step?I'm very curious as I am still deciding which Dob to buy,wish I had a lathe.Just trying to help.

[John]

John,does it have stepped portion for the flange?If it is stepped what is the O.D. below the step?I'm very curious as I am still deciding which Dob to buy,wish I had a lathe.Just trying to help.

Someone was making a custom adapter to fit a camera to a Skywatcher scope and came up with the following profile for the adapter required (see photo below). This seems to match the profile of the Skywatcher 2" and 1.25" adaptors as I recall:

[jetstream]

It depends where you measure it as it tapers. It's 57mm or just a fraction under at it's widest as that is the inside diameter of the receptacle on the end of the drawtube it has to fit into.

Sorry I posted after your reply, I have to take the grand daughters fishing right now....they are jumpin all around here waiting!But when I get back I would like to figure out the dimensions if anyone has them-57mm almost 2.25in and a taper,with a perpindicular 2" hole inside interesting.Are they using this as a locating measure to help collimation repeatabilty or are they trying to keep other adapters out of there?

[jetstream]

Thanks John,I'll be back later.

[John]

What I'm keen to do is to find a practical solution to skywalker3's problem. It's not a simple one to solve though, unfortunately.

[skywalker3]

What I'm keen to do is to find a practical solution to skywalker3's problem. It's not a simple one to solve though, unfortunately.

Thanks for your help John, although I have found it confusing, I think the simple answer is it is not easy to do.

My aim was to get some more eyepieces of a smaller size, down to around 15mm, but it appears that after more searching, at this smaller size, the ep's are 1.25".

So what I have decided, is to get a Seben 8-24mm zoom ep and a skywatcher 1.25" UHC filter and see how I get on!!!

[Joves]

Are you sure you're only 11?? Old soul by the sounds of things!

[Andyj]

Without wishing to grab the attention in this thread but to add to my previous interest in this thread, I just took the plunge and ordered the Skywatcher O-III 2" which I hope will give me good results. But in the process of ordering I noticed that Explore Scientific seem to be offering UHC and O-III filters which I had not seen before. Perhaps I had missed them but they seem competitive in price and I notice they appear to come with a spectrum report showing their performance, which I thought was interesting. Is that a standard practice or a particular extra with these features? Does anyone have experience of using either or both of these? I would be interested in seeing feedback.