John

In the words of Hawkwind, "Hurry on sundown, see what tomorrow brings"

It's Copernicus. I got it myself a little while back with my Tak 100 and my old Samsung mobile:

Less power usually makes things crisper. I always prefer a smaller scale sharp view to a larger scale mushy one. There are some exceptions to this, usually when I'm searching for a very faint point source such as a supernova or one of the fainter planetary moons.

You could try less magnification - 450x is a heck of a lot even on the moon and only under the very best seeing conditions and with the scope collimation absolutely spot on will it result in sharp views. With my 12" F/5.3 dob I often get my sharpest views of the moon at around 280x - 320x. Occasionally I can go a little further and still get a sharp view but most of the time things get softer above that sort of magnification, rather than sharper.

I use a Rigel Quickfinder which is just this side of the RA finder - It's not a good photo ! This shows the arrangement better and the Moonlite focuser that I now have fitted:

I'm just the same Ade.

I would have thought that focuser and extension would have done the job, unless the focal plane on your scope is unusually far out from the tube wall ? This was the original focuser on my 12 inch F/5.3 which worked well with a wide range of eyepieces including the Myriad 20mm. It looks a similar in proportions to your current setup:

The UNI 18 will make a difference (I have the UNI 28). Not only is it a more stable tripod than the stock 1.75inch one, the ash wood absorbs vibrations well - thats why they make hammer handles out of it. The UNI tripods are even better than the 2 inch steel tubed ones - I just did not realise you had one !

The longer tube will have an impact, thats for sure. The more stuff you can add that minimises the need to touch it, the better the vibrations will be controlled. If one comes up, the 2 inch steel tubed Celestron CG5 tripod is taller and quite a bit more sturdy than the 1.75" steel tripod. Might be worth considering. I used to use a 150mm F/8 and also a 127mm F/9.2 refractors on a CG5 (same as EQ5 really) on the 2 inch steel tripod and it did a decent job for visual observing.

This older classic EQ mount landed here today - Vixen GP in Celestron colours. A nice alternative for my 100-120mm refractors and I'll be getting at least the RA axis driven for relaxed high power observing. I've not owned a GP for a long time and I'd forgotten a) how well made they are and b) how light they are for their capacity. Nice Japanese manufacturing

Is your EQ5 driven Ade ? I've found having a driven mount makes a lot of difference to vibration handling with a long scope on board. A sturdy tripod is impoartant as well.

It was an option that OO offered for a few years but not enough demand aparrently and it was harder to fabricate I believe. I still get diffraction of course but it's spread evenly across the field of view. No "spikes" either side of brighter stars. They were fitted to the scope when I purchased it (used) and I've seen no reason to change them. Martin Mobberly opted for the same pattern when he comissioned his 10 inch F/6.3 from OO: https://www.cloudynights.com/articles/cat/user-reviews/telescopes/dobsonians-10-40/orion-optics-250mm-f63-spx-newtonian-r621 My scope is the 12 inch F/5.3 version of his.

Agreed. I use a "half moon" light shield around the top of my tube on the side where pesky local lights have been known to shine and it has improved contrast noticably on DSO's.

Good news ! - look forward to meeting up with FLO folks again there

I have the feeling that a 125 doublet might be along sometime. I may be wrong but it would not surprise me in a couple of years if the FC line was a single 100mm (the DZ) and also included a 125mm and maybe even an 80mm ?

Apparently, with the dew shield retracted and the diagonal plus extensions removed from the focuser the DZ measures 595mm in total length. It weighs 3.8kg.

Takahashi FC100-DL on Giro Ercole mount observing Jupiter this evening. Lovely views at 180x with the Pentax XW 5mm

It's not OOUK's fault. It's eyepieces / imaging devices / 3rd party focusers / the speed of light that are wrongly configured

Ooops !!!! - I don't know where I got F/8.2 from - the DZ is F/8 "native" focal ratio. Must have misread something !

That would require a re-design of the objective lens cell which is perhaps not a small matter ? Looking at the performance charts and spot diagrams and comparing them with those of the FC-100DL I think the important point is not so much that the peformance at F/8.2 looks to be very, very close to that of the F/9 but that when the .66x focal reducer is used, the spot sizes remain very tight even at F/5.3. This seems to me the key feature optically of this doublet - it remains a very high peformer even when focally reduced. Imagers will be attracted by that.

F/8.2 fluorite doublet which fits between the F/7.4 and F/9 of the DL and the DF / DC models. Sliding dew shield, which is a nice touch. The performance charts look pretty good - they claim that it's as good as the F/9 but with the advantage of the faster focal ratio and faster again for imaging with the .66x reducer in use - just F/5.3. It's a sort of homage to the original FC series back in the 1980's according to the translated web page. Maybe an 125mm version on it's way as well ? (thats just a guess !). Another desireable Tak ! Maybe the F/9 won't be produced again and the F/7.4 models will be replaced in due course by this single multi-use focal ratio model ?

To be "faulty" in that way the field stop and internal optical elements of thye eyepiece would have to be moved within the body of the eyepiece by a large amount which, as far as I can tell from what I know of the design, is virtually impossible unless someone has dismantled the eyepiece and re-assembled the elements (there are about 7 or 8 of them) completely incorrectly. It would be very unsual for OO to blame their own scope though

Thats odd - when I tested the Myriad 20mm I seem to recall it came to focus in my 12 F/5.3 OO scope at about the same place that the 21mm Ethos does - plus or minus a mm or two

If and when you decide to go for a Moonlite focuser, go for the 10 inch tube fitting kit. The 12 kit fits Skywatcher, GSO, and Orion (USA) tube diameters but Orion Optics tubes are a bit slimmer so the 10 inch kit is a much better fit I found. Orion Optics tend to position the focal plane of the primary mirror further outside the tube wall than the other manufacturers I've mentioned here (the slimmer tube plays a part in that) which is why you need extension tube(s) or the Moonlite risers to get eyepieces to reach focus.

I did need to make 2 holes in slightly different positions but the tube is aluminum so this was not a difficult job. See how you get on with the focuser that is already fitted though - it looks a decent unit. What 20mm eyepiece are we talking about here by the way ? - most eyepieces have a focal plane that is within 10mm of each other but one or two types vary a lot so will need much more focuser movement than ordinarily necessary.