John

I've been though the "must own full set / all the same brand" thing but eventually realised that I was not doing myself any favours with regards to the overall effectiveness of such collections so now I've gone back to cherry picking from ranges and (generally) not owning focal lengths that don't do something useful with my scopes / sky conditions / observing interests. I still can't shake off the draw of wide, expansive fields of view but that may well be because all my scopes are used on undriven / alt-azimuth mounts. In saying that my current eyepiece sets cover from around 40 degrees to 110 degrees so I have plenty of variation available

Perhaps this thread could be widened to include GSO-made dobsonian scopes ? There are quite a few of those around aleady so the thread might have some more variety in it ? Just a thought !

Well it does "work" but the result is not really a surprise. It was just a bit of fun really - is the stock 10mm really that bad ? and what are the actual, tangible, differences between eyepieces with a 10x difference in price tag ?. I'm sure the more predictable comparisons have been done somewhere over the past few years. And then debated for another couple !

Thanks Chris Forecast does not look great here but you never know how things will actually turn out at 1:00 am ! At least Jupiter will be above the hedges and rooftops by then

I bought a brand new William Optics "Vixen type" DT bar a couple of years back which turned out to be a little narrower than the "standard" size, whatever that may be. My ADM clamps didn't hold that one either Fortunately the supplier was FLO so a return / refund was speedily arranged but I was a bit baffled as to why WO decided to make these bars just a little narrower

Most often folks end up with one or two 2 inch eyepieces in their sets to deliver low power / widest angle views with scopes that take that fitting. In medium to shorter eyepiece focal lengths the 2 inch fitting does not provide any benefits so eyepieces in those focal lengths are in the 1.25 inch fitting. This is broadly what the chart that @Louis D illustrates. The barlow you have purchased can be used with either 1.25 inch or 2 inch eyepieces, the former requiring a suitable adapter.

Ain't that the truth !

Sorry that you have have had a run of bad luck with astro Dave. I sincerely hope that things pick up from here on for you Since I've owned the Tak FC100-DL and the TMB / LZOS 130 F/9.2 triplet (over 5 years now, believe it or not !) I've realised just how good my old ED120 is. Maybe mine is an above average one ?. It's one of the early gold / cream ones previously owned by a very experienced person. I bought 2 scopes from him and both turned out to be crackers so I think he knew what he was about ! Cloudy again here tonight though so more patience required

Another one of my favourites (the Pentax)

Interesting report - good to know ! After reading reports like this I often consider why so many of us have cases full of premium eyepieces I guess there must be other reasons that they appeal to us !

Poor conditions here limited my comparisons to a "quick and dirty" look at Epsilon Lyrae, Pi Aquillae and Messier 57, the Ring Nebula. The scope was my ED120mm F/7.5 refractor. With the Celestron branded K10mm "stock" eyepiece (not marked "super" at all ) the views in the central 50% of the field of view were sharp with this scope but splitting these close star pairs became harder as the target neared the edge of the field of view and in the last 10% or so the splits were practically impossible to make. I was using the Baader 2.25x barlow lens with the K10mm to make it a 4.4mm for Pi Aquillae. The comparison eyepieces were, really quite unfairly, the Pentax XW 10mm and the Tele Vue Nagler 2-4mm zoom at the 4mm setting. I also used the Hyperflex (clone) 7.2mm - 21.5mm zoom eyepiece at the 10mm setting as another, less pricey, option. More than the sharpness fall off towards the field edge, the most notable difference between the more expensive eyepieces and the stock K10mm was the brightness of the views. Although a simple 3-element design, the K10 views of both the star fields and the Ring Nebula just looked dimmer all over. When the better (and much more expensive) eyepieces went in, the difference was noticeable with the fainter stars in the view popping out more obviously and the contrast variations across the surface of the nebula being quite a lot easier to see, despite the rather poor observing conditions. To be fair, the K10mm stock eyepiece was quite usable and the view in the central portion of the field of view was by no means bad. It was just a dimmer view and lost sharpness towards the edge of the field.

I think the Zhumell range is practically the same, at least in the 8, 10 and 12 inch sizes.

That would be interesting. I have the 20mm and 10mm stock eyepieces branded Celestron knocking around somewhere. It would be interesting to compare the 10mm with, say, my Pentax XW 10mm and see just what the "gap" between them is - I wonder if it is £230 quids worth (assuming that the 10mm stockie is worth around £20 new)

Quite a decent eyepiece as it happens Stu

The mirror clips would stop the mirror from falling forward from the cell but should not be pressing hard against it. Yes, the cork pads were stuck to the triangles and the back of the mirror just rested against them.

I took the primary mirror cell off the end of the scope tube. I then turned the whole thing upside down with the mirror face protected and facing downwards, removed any clips and screws holding the mirror in the cell, applied a drop or two of white spirit to each sticky pad and allowed it to soak though, After some time (a couple of hours) I was able lift the whole mirror cell off the primary mirror. Some times the pads might need a bit of easing or even cutting which is where the fishing line / dental floss comes in. When I put the mirror back I used small cork pads instead of the sticky ones and did not stick the mirror back in, relying on the mirror clips and gravity to stop it moving around. It's important not to tighten the mirror clips down onto the mirror - there should be a very slight gap (playing card thickness) between the clips and the mirror surface. Sorry that it's a bit of a faff. I don't think the primary cell design has changed in the past 20 years with these. Another tip is not to use the locking screws once you have collimated. The mirror cell is quite thin and the locking screws seemed to cause flex when tightened which moved the collimation out again !

I found this on another forum about this issue: https://www.cloudynights.com/topic/396951-12-gso-mirror-removal-and-re-mounting/

I found the same when I tried to remove the mirror from my 12 inch Meade Lightbridge, which used the same primary mirror and cell as the Revelation 12. The mirror was fixed on to the cell by a number of small double sided sticky pads which need to be soaked with white spirit to loosen them and / or cut with fishing line or dental floss, so that the mirror can be removed from the cell. It's a bit of a chore to be honest but it can be done.

The Norman Lockyer observatory near Sidmouth is an easy trip from you now - great place to visit and observe if you get a chance !

Congratulations Stu. Glad the move went OK and welcome to Zummerzet ! Nice area, Crewkerne

No problem and welcome to the forum

Hi, This problem is usually caused when the Skywatcher 1.25 inch eyepiece adapter is used in the scope at the same time as the 2 inch eyepiece adapter. These adapters need to be used separately rather than together.

That list was from Richard Suiter's "Star Testing Astronomical Telescopes". I guess we try and optomize as many factors as we can to give ourselves the best chance we can to get the best results. I've seen others argue that the eyepiece is half the scope convincingly

Great to see that the Delite is delighting you ! From what I've read about them, the Delites seem to have the just about best optical properties of all the Tele Vue ranges currently Unless you count the Tele Vue Apollo 11 as a "range" I guess

Nice range of dobs at good prices Good to see an RACI finder on the 8 inch and upwards models