John

As you will have gathered, the answer to your question is "it depends ......" All the scope designs have their strengths and weaknesses so to help you make a decision, we are going to need to ask quite a few questions. Many folks end up with a number of scopes of different designs and sizes to give themselves different observing and imaging opportunities.

I think that way - shims behind the mirror is the best way to do it. There will be some trial and error in it so maybe not sticky shims until you know how much tilt is needed ?. Probably not a lot.

I use a short cheshire to collimate my 12 inch F/5.3 dob. I've been using it for a few years now so it's become 2nd nature to use. I rarely need to do more than adjust one or other of the collimation screws a tiny bit just to completely centre things. I have tried a number of other collimation aids over the years but having found one that was simple and that worked and was consistently backed up when the scope is star tested, I've stuck with it.

I got a copy of this book (1st photo) to add to this book (2nd photo) which my wife bought for me around 35 years ago. Not everyone's cup of tea by any means but I rather enjoyed the original book so I'm interested to see how the author followed it up. I have just found out that, very sadly, Ken Fulton passed away earlier this month

I have a Vixen ED102SS F/6.5 which dates from around 2000. Obviously the optics have changed to F/7.7 but otherwise your scope looks like a longer version of mine

Hyperions and F/4.7 don't mix well in my opinion. The ES 68 and Vixen SLV's are much better choices. Nivarna 82's are great value if you would like the wider field of view. If you are fussy about edge correction and decide to use wide or ultra wide eyepieces you might also need to consider using a coma corrector to get the best out of them. That will correct much of the coma that the fast newtonian optics produce. I won't talk about Tele Vue or Pentax Sorry that @wookie1965 and I disagree about the 25mm BST Starguider. I'm sure we are both calling it as we found it

I have the older Japan made 11x70 Opticron Oregon LER's and they operate at full aperture as well. Out of production now though.

Yes but it's pretty faint. With my fracs I can detect the E portion without a filter. With my 12 inch dob the E & W portions. It's so much better with the O-III filter that I rarely observe it without though. On one memorable night a few years ago I was able to see the E segment with 15x70mm binoculars unfiltered. That was a truly exceptional night though.

As Steve says above - the HEQ5 is a very different mount to the EQ-5 and much more capable. In the USA it is more often found branded as the Orion Sirius EQ-G.

I agree with Jeremy on both counts - great scope ! I have edited your post to remove the image that shows your address. Feel free to add one with the address blanked out. Hope that's OK

There is an HEQ5 that lies between the EQ5 and EQ6 in capacity, which is not show in Alan's pictures. The so called EQ-4 has been seen in lots of brandings over the years. I feel that it has no greater capacity than an EQ3-2 (to give the mount the Skywatcher name) and possibly even a little less.

The sticker will say: TELESCOPE D=200mm F=1000mm Coated Optics Made in China

The mount is an EQ3-2 / Skyscan 2001 or clone of. Orion Optics used to supply a version of it and called GEM 1. The scope is a more recent Explorer 200P. The mount is not really up to that scope.

My locality is rated as Bortle 5 by "Clear Outside". Maybe that's an average figure and parts of the sky are better than that

That's pretty much the difference I see when using my 12 inch dob at home

If you got for the lightweight alt az mount option (eg: the Pronto, Porta etc, you are going to be restricted to around a 130mm aperture newtonian really. There always seem to be trade offs to make: aperture vs portability, price vs quality, etc, etc. It is possible to source or make 6, 8 or 10 inch aperture ultra portable dobsonians but these either require good DIY skills / facilities / knowledge of scopes or a fair budget: Here is a 6 inch ultra light dob project from a member here @astrolunartick:

The 25mm BST Starguider is not the best peformer of that range, I agree. I had one and it worked OK at F/7 but showed quite a bit of astigmatism in my F/5.3 dobsonian. The 30mm Vixen NPL is a nice eyepiece and sharper across more of the field of view - I liked the ones that I've owned:

A very good scope. Pretty much the same as the Skywatcher Skyliner 250PX and there are a lot of fans of that scope on here. The Orion 10 inch will show deep sky objects better than the TAL or the 150mm refractor can because it gathers more light. On the moon and planets it might be a closer call between the 150 refractor and the dob but the 10 inch dob will not show any false colour of course. Hope you enjoy it !

If hand held observing is something you intend to do often, the 11x70's make that a bit easier. The Skymasters actually operate at a slightly reduced aperture due to the prism design I believe - about 65mm ? Not sure about the Opticrons in that respect.

Interesting eyepieces the Baader Classic Orthos for a touch under £50 a punt. I reviewed them for the forum a while back:

You can put these optical tubes on an alt azimuth mount such as the AZ-4 or Vixen Porta II (latter shown below):

With nebulae, but not with galaxies ? I suspect that's what you mean though

Quite right Stu - such filters do help with nebulae under LP skies - in some cases at least you see something ! My post should have made it clearer that galaxies won't benefit in response to @Colossal Plossl's comment on the visibility of the Andromeda galaxy.

They do look lovely, don't they ? I fitted a 2 speed Moonlite to my 12 inch dob and had similar fun with the fixing holes. I wonder which scopes they do actually match ? Will the new owner miss having a 2 speed focuser do you think ?

Deep sky filters such as UHC and O-III don't really help with galaxies and clusters. Nebulae are the targets that they enhance, some more than others.