John

I have the Astronomik H-Beta in the 1.25" size. Apart from the Horsehead Nebula I have not really used it on much else

I'm glad that I have it because seeing the HH was a long held objective of mine.

My UHC and O-III filters see a lot, lot more use.

Perhaps we need a rental / loan arrangement for these seldom used tools ?

I would get a mirror diagonal for an SCT.  Good quality prism diagonals work well in slow refractors. not so sure if the bring the same benefits to an SCT ?

By all means buy the Celestron if you like it's looks but be aware that you are probably paying £70 for those looks. The underlying diagonal is the same as the Skywatcher one and almost certainly made by Synta who make Skywatcher stuff and own the Celestron brand now.

They are excellent scopes. Large and heavy though.

You will probably want more eyepieces plus some collimation tools, a Telrad and a RACI optical finder.

While the Moonlite focusers are very good but why not try the stock one first ? - they are not that bad at all. I would probably invest in the list above before rushing to upgrade the focuser.

I use this approach when I'm using the barlowled laser collimation method. It works well for me

http://www.smartavtweaks.com/RVBL.html

Mind you, the collimation adjustments that my F/5.3 12 inch dobsonian requires are generally very small so usually I just use a cheshire eyepiece and then a quick star test to check.

1 minute ago, JamesF said:

I've been sitting in a recliner outside this evening in my shorts and t-shirt, peering through the clouds and Perseid-spotting.  I've seen quite a few lovely ones, as it happens.  There's an awful lot of flickering of the clouds as well though.  Either my eyesight is seriously dodgy (I thought it was only the morning after that you were supposed to find you'd gone blind?) or (I assume) I'm seeing some of the light carrying from the thunderstorms currently around Birmingham and Coventry.  I'm struggling to believe it carries that far (100 miles, ish?), but that's my preferred working hypothesis for the time being.

James

I'm doing something similar here.

There is quite an electrical show going on towards the north currently. Either Pink Floyd have reformed and are playing a monster gig or there are some thunderstorms over Chepstow and the Wye Valley.

The latter is more likely I suppose

I have recently bought a Skywatcher 1.25 inch diagonal to use in a small mak-cassegrain. This one:

https://www.firstlightoptics.com/diagonals/SWdiagonal-20967.html

Although it does not have the twist lock eyepiece clamp that the Celestron does, it is otherwise identical and my guess is made by the same manufacturer. I bought mine 2nd hand for somewhat less than the new price and a lot, lot less than the Celestron item is listed at.

The diagonal works very nicely but I don't think I would pay £100 plus for one, even with the twist lock clamp.

I don't know quite how this feeds into this interesting thread but one of the times when I find using very high magnifications useful is when I'm trying to see faint point sources such as the dimmer planetary moons.

When I've observed Neptune's moon Triton and Titania and Oberon at Uranus I've found that really high magnifications (400x plus) have been helpful in teasing these faint points of light out of the background sky and the glare of their parent planets.

Sometime over the next couple of months I'm hoping to use my 12 inch dobsonian in this way on Mars to try and spot Phobos and Deimos.

5 minutes ago, Peter_D said:

I see somewhere like ENS Optical in Birmingham often have second hand Meade and Celestron SCTs for sale - this should give you a good pointer in coming up with what your scope is worth.

You have to be a little careful there. Their pricing is, I would say, somewhat higher than a personal sale is likely to realise. 

Done.

I had similar issues to @davew on some of the terminology used so I used a best guess there.

Takahashi FC100-DL tonight. Lowest power that I had a confident split of both pairs was at the 13mm setting of the zoom so 69x.

21 hours ago, A McEwan said:

I've had two of these 90mm Evostars in the past (maybe three actually...🤔) and they performed excellently under the stars with well aligned optics. The focusers needed cleaning up and regreasing, but this one's coming with a 2" Crayford already attached so that's (probably) one foible pre-empted. I'm highly optimistic it will be excellent for solar - as long as it's generally a good 'un!

I currently have the Celestron branded 90mm F/11 and it's proving to be a nice performer as well

I find that using a higher magnification with a wider field of view helps me to find faint objects a little easier because the background sky is darkened enabling the deep sky objects to be just that little bit easier to spot. I observe mostly from an area with some light pollution. I have 40mm, 31mm and 21mm eyepieces which all show around the same amount of sky. The 21mm (which happens to be an Ethos) is that one that gets used the most for deep sky sessions.

The 20mm Myriad or APM 100 degree eyepieces are a lot less expensive than the Ethos 21.

The scope that I would be using mostly for this is a 12 inch F/5.3 dobsonian.

The 7mm will see more use although my my 12 inch F/5.3 I find 6mm the "goldilocks" high power much of the time. I do use the 5mm XW quite often to tease out the finer lunar details though.

I hesitate to say "get both" though because it's so easy to spend other peoples money !

I'm going to be experimenting with my Giro Ercole this evening. Fortunately I have quite a lot of scopes and counterweights to play with !

Forums are really helpful with these sorts of issues - a number of folks kicking ideas around can be really productive 

Good seeing here just now. No filter (Tele Vue discontinued them after a couple of seasons) but the Martian disk looks pretty much like this with the Tak 100mm:

The "african continent" shaped darker area may well be the Syrtis Major. It has a rather triangular shape.

The airy disk / star test is done on stars rather than planets.

I think the lesson is clear with these "T" type mounts - balance is the key to getting the best from them and that needs some experimentation to get "just right". Even more so than I originally thought.

1 minute ago, Tim said:

It wouldn't make much difference when observing under typical conditions John, as you say, but in newts used for imaging, which typically have LED's, and laptops etc around, stray light entering the rear of the scope can actually go through the mirror, and appear in an image as a large donut shaped anomaly. It took me ages to figure out what was causing the issue, on an old GSO 8" I had. Since then, if using a newt for imaging, I always put a cover over the rear end.

Tim

That might explain why the put one on the EQ mounted newtonians but not the dob's then !

Thanks Tim

One of the members of my astro society. Eddie Carpenter, has an asterism named after him - Eddie's Roller Coaster. It is a nice binocular target in Cassiopeia and included in this BAA list:

https://britastro.org/journal_item/22500

There should be a rubber O ring around the finder tube sitting in the narrower of the two grooves - towards the front end of the finder body.

Without it the finder simply will not stay in place in it's mount.

10 minutes ago, Stu said:

Having used this very mount, I know just how good it is John. The slow motion cables are the best I’ve ever seen!

I would buy one like a shot (if available) if it weren’t for my love of dual scope setups. The AZ100 just has a great combination of load capacity, slo motion controls, encoders and dual mount capability which is hard to match.

Good point about dual scope setups Stu - when I want to do that my Skytee II copes with it quite well or even the Ercole. I don't use two scopes that often though.

When I was beta testing the AZ100's I found that I needed two of their 3.7kg counterweights on the other side of the mount to get smooth slow motions with my 130mm F/9.2 triplet. This would have led to a rather heavy set up had I decided to go for the Rowan mount. The T-Rex, as I'm sure you know, needs no counterweights at all.

1 hour ago, A McEwan said:

As this thread includes "from our Dob history" -and I'm not sure if I shared this on here, here is my long-departed GSO 8" f6 Dob.

It started off basic enough, but after a while I stripped it all down, sent the mirrors for Hi-lux coating, sprayed the interior flat black, sprayed the exterior in Peugeot Blaze Yellow, added a "steering knob", added a Skywatcher electric focuser motor (later on I upgraded to a Moonlite with motor drive), added a proper flexi dew-shield, Bob's knobs, uprated collimation springs, had magnetic counter-balance weights instead of the tension-adjuster springs, did some work on the base to make it super-smooth with just the right amount of stiction.....and.... it was a GREAT performer! Had many great nights with that scope - but it always point blank refused to show me the Horsehead! 

It's one of the scopes I shouldn't really have sold, but I'd kind of tired of it and wanted something else, so it went. Later on I would get the 10" GSO and even a 12" Driven Skywatcher Dob, but both of those went fairly quickly as they were a bit too cumbersome for me to transport easily.  Oh well.

My first dob was one of those. Mine was white and branded "Revelation" but it was the same scope. I bought it for just £100 used and was rather surprised when it performed as well if not a bit better than the 8 inc Celestron SCT I had at that time.

The GRS was quite clear at that time with my 90mm refractor at 80x magnification. Just where @CraigT82's pic shows it.

Well done for getting it !

1 hour ago, Robindonne said:

Yes thx.  Thx for all the info btw.   Im going to play with it a bit tonight.   Was just wondering if certain eyepieces get in focus quite quickly/short vs ones that need to be more outwards(the focustube). But i guess that also varies from scope to scope.  If i suddenly see some cloudbands moving on jupiter tonight ill let you know!🙂

Not all eyepieces reach focus at the same point by any means. Not even in the same eyepiece range in some instances.

40 minutes ago, Uplooker said:

As lenscap says👍

Agreed 100%

Skywatcher uses these back plates on some of their newtonians and not others. Don't know why they put them there but they can be removed and left off to be honest with you. They actually slow down the cooling of the scope as well as getting in the way of the collimation screws.