John

That's sound advice 👍

I find that the the 45 degree face of the cheshire needs to be really well illuminated to see the reflections clearly.

APM/LZOS refractors have used a similar approach for years. My LZOS 130 is 17 years old and has an extension tube at the focuser end. No signs of droop with it even with a 2 inch diagonal plus 21mm Ethos installed. The Askar approach looks even better engineered than the APM/LZOS one I think.

Apologies if you know this Stu. What we are looking for is the reflection of the illuminated face of the cheshire. It shows on the rear faces of the lens elements as two small disks of light with a dark central hole. Ideally they will be one on top of the other. If the objective is tilted or the focuser is askew, they show as two disks not overlapped or even side by side. Apologies again if you know all this and have seen such illustrations before.

I was attracted to the F/9 100 Tak because I already had the F/6.5 Vixen. I was on the look out for a Vixen FL102 at that time but, as is often the case when you start to look for something specific, they became like hens teeth to find 🙄

Quite right. With the 185mm there are the mount, the observatory and the divorce costs to factor in ........ 😬

So are we in the UK 😒

Evil man ! 😈

That looks pretty good to me @Stu 👍

I keep looking at the 140mm F/7 triplet. For quite a while I was interested in the APM 140mm F/7 ED doublet and now here we have a triplet at around £1K less !!! 😲 The 185 is amazing as well but I'd need a massive new mount for that whereas the 140 would go very nicely on my T-Rex alt-azimuth 🤔

Who is going to be brave enough to start a "Ménage À Trois" thread ? 🙄

There are a number of sturdier alt-azimuth mounts that have slow motion adjustment controls. The Skytee II and the Sightron to name two of those. If you decided to go for a Tak FC100 F/7.4 (DF or DC, especially the latter) you might find that the Vixen Porta copes OK with the lighter tube. I used to use a Vixen 102mm F/6.5 on a Porta with some success and that weighs around 3.4kg.

That's just what I was going to suggest 👍

Thank you. I'm very fond of them all, even the old Skywatcher ED120 🙂 This could prove problematical if and when I want to downscale my equipment though 🙄

Agreed - a big chunk lower.

I have seen a couple of used ones for sale since I bought mine, but only a couple. I've no idea how many were made in total. A couple of thousand I guess ? 🤔 Quite common though, compared with the (off-topic) TMB/APM/LZOS 130 F/9.2's and the Tak FC100-DL's which seem to have total production runs at the sub-200 units level 🙂

I use the FT micro pinion on my FC100-DL and the Baader Zeiss T2 prism or an AP Maxbright if I want a 2 inch diagonal. I've not tried an MEF-3, More Blue or a Tak prism. They are probably very nice 🙂

For quite a long time I got on well with an 8 inch dobsonian and a 4 inch refractor so I'm sure that I could "make do" with those again 🙂 It's just getting there that would be the painful bit 😬

That's good news. I've just parted with some nice abbe orthos because the Sv 3-8 zoom showed Saturn and Jupiter just as well with the benefits of zooming, more eye relief and a wider AFoV. Svbony have a good one here 👍

I'm a huge Ed Ting fan. I have read his web site for over a decade now and watched quite a few of his videos. I've taken some of his recommendations on scopes and found them spot on. I have watched a few others but Ed is unmatched IMHO.

I have one just like that. There should be hex screws in the 3 holes next to the 3 philips holes. They might be in those holes so don't panic ! The philips ones are the primary tilt adjusting ones and the hex screws are the locking ones. The other 3 smaller holes should be empty. So just to reassure you, mine looks just the same as yours and collimates fine 🙂

The movement that I think might be required to centre the secondary in the focuser tube is along the optical axis of the primary. I have indicated with red arrows that direction of movement:

I'm concerned that it might revert to a somewhat higher price in due course. If the eyepiece bore more prestigious branding I think it's price would be far higher.

The 3-8 zoom compares very favourably in build quality, and surprisingly well in optical terms as well, with the Tele Vue high power zooms, which cost nearly 4x as much. I could well understand the Svbony 3-8 being priced at around £250 or even more considering it's quality, but it's not and, IMHO, rather a good buy 🙂

With the Explore Scientific secondary mirror support design I am unsure how you would adjust the position of the diagonal along the optical axis of the primary, which seems to be what is needed to centre it under the focuser 🤔 The tilt of the diagonal is clearly adjusted by the 3 screws pictured in the photo that @dweller25 has posted above. But how can you move the secondary mirror closer to or further away from the primary with that design ? (which I think is what is needed) Edit: I can see that @Ricochet is having similar thoughts !