John

Great report Nick I was using my ED120 last night at our society obsevatory for an outreach session. Best views of Mars this season and many other targets as well. These 4.7 inch fracs certainly pack a punch for their aperture. The other scopes there were an 8 inch SCT and an 18 inch newtonian but many remarked how well the ED120 showed the various targets.

You would get a slightly wider true field from a 32mm plossl or a 24mm 68 degree eyepiece (ie: max field stop for 1.25" format). With your 150 mak-cassegrain: 25mm X-Cell LX = .83 degree true field 24mm 68 (eg: ES 24 / 68) = .91 degree TF 32mm plossl = .92 degree TF Thats about as much sky as a 1.25" eyepiece will show with the scope. Longer focal length eyepieces in that format don't deliver a wide true field.

Astro society meeting in Bristol earlier tonight. I took a small scope up so that we could show some younger astronomers the Moon, Mars and Saturn, from the centre of Bristol. They seemed to enjoy that - first sight of Saturn for some of them . Back home now with the same small scope out doing some more lunar observing and some binary stars. Rather too hazy for deep sky stuff. Hopefully up at the society observatory tomorrow evening for some more outreach. It's International Observe the Moon Night tomorrow you know !

Straightforward piece here on SCT collimation: https://starizona.com/tutorial/collimating-a-schmidt-cassegrain/ Interesting that they feel that the stock collimation screws are better than the after market ones like Bobs Knobs etc. Personally I got on quite well with the latter. As Tim says important that the star is centered and then re-centered again after each adjustment to see the progress towards accurate collimation.

I'd love to see a photo of that setup - the 40mm 5K Meade is a huge eyepiece ! (you have de-cloaked yours though I seem to recall ?)

I was just going to make the point that Michael has regarding the implications of the F/5 focal ratio of the Nexstar 130 SLT. I agree with his viewpoint that an 25mm - 30mm focal length eyepiece would be more suitable.

The tripod is probably the weakest part - it's not really up to carrying a 200mm reflector. If you could replace the aluminum legs with wooden ones it would be much better. You will probably need to re-use the tripod hub because that is specific to that mount. Even though the "Helios" name was used in the past by the manufacturer Synta, who later re-launched the scopes under the Skywatcher branding, the mount shown above is not a Synta product and I doubt that the scope is.

I've seen that tripod and mount supplied with 200mm F/4 newtonian telescopes but they are not Skywatcher scopes. This is the nearest that I can find to it: https://www.alibaba.com/product-detail/-BM-800203EQ-IV-A-Outdoor_60318555148.html Sometimes the scope tube is branded "Helios" but this is not the same as when the Skywatcher manufacturer used that branding. They are made in China but I don't know any more about them. There used to be a review on the net somewhere but I can't seem to find it now. Sorry I can't be of more help.

The core of M31 is much brighter than other galaxies we can see so if that is faint then other galaxies are going to be really challenging. I agree that M81 and M82 are the next best options followed by a few below Leo when that constellation is rising at a reasonable time. Light pollution kills galaxies pretty effectively unfortunately. Under dark skies even 50mm binoculars will show quite a few.

The field stop of the eyepiece limits the apparent field of view that you can get with a 1.25" barrel format as follows: 24mm = 68 degrees 32mm = 52 degrees 40mm = 43 degrees If you do the maths you find that all the above show pretty much the same true field of view so going for the longer focal length alters the exit pupil size but does not show more sky. Personally I prefer the 24 / 68 approach because of the darker background sky and wider apparent view are more pleasing to my eye. It might be possible to use a focal reducer but I suspect that vignetting (loss of light) at the field edges due to the internal diameter of the rear port of the scope might limit the gains made from that approach. When all is said and done, the mak-cassegrain is not a wide field design. Sometimes one has to "bite the bullet" and get a faster focal ratio scope, such as one of the F/5 refractors or a newtonian, to get the wide fields of view. This is why many folks end up with more than one scope

Just back from a social event, was going to get a scope out but I think I'll take the binoculars out instead ! Thanks for the heads up re: the poor seeing.

It's an Istar 150mm F/12 achromat that I owned for a while. More on it here: https://stargazerslounge.com/topic/213471-istar-6-inch-f12-equatorially-mounted-achromatic-refractor/

After seeing the pictures of the casting issues above (bottom 2 photos), a while back I partly dismantled my Skytee II and checked out some of the internal surfaces. They are much sounder on my unit than those pictured so I can only assume that there are inconsistencies in manufacturing. I guess if the Skytee II was made to similar standards as say a Giro Ercole, Losmandy AZ8 or an AYO, it would cost considerably more than it currently does. False economy if your scope drops off one of course .....

I believe that there are reasons why some manufacturers choose to recess an eye lens: - to reduce the build up of dust / eyelash grease - to reduce the propensity for dewing up. The figure of the eye lens is often concave for wide and ultra wide eyepieces, thus reducing the useable eye relief. Eye relief is measured from the centre of the top surface of the eye lens so if it is deeply concave and the eyecup relatively inflexible, viewing comfort is not what it might have been. It would help if the eye relief quoted was the useable eye relief, I agree. Lots of options around to choose from though so all tastes are catered for

Probably not. I get a bit nervous with my TMB/LZOS 130 F/9 (9.5kg) on one side and 7kg of counterweights on the other so I check the movement and condition of the mount regularly. Neil English put quite a bit of weight on his Skytee II though - this is a 204mm F/5.9 weighing 14.7kg: