John

According to Stellarium modelling Mimas has just (in the last hour or so) passed the point of greatest elongation from the planet / rings so will be moving back inwards, and therefore become harder to see) over the coming hours. The mist is rising in the south now and even the mag 10 moons are hard to spot so I'll have to wait for a further favourable elongation to try again. Quite encouraged though 🙂

Really good seeing conditions with my ED120 on Saturn this evening. As well as Titan, Rhea, Tethys, Dione and Iapetus I think I am getting some occasional glimpses of the magnitude 13 Mimas now and again. Mimas seems to lie on the Rhea side of the A+B ring system, just a touch S of the equatorial line of the planets disk and about the same distance from the edge of the A ring as the total width of the A+B rings together, if that makes any sense. I'm using 300x-360x to get these glimpses. That is a little more than I need for the sharpest Saturn views but it helps tease out the fainter points of light. I'm hoping to get clearer sightings of Mimas as Saturn rises but if anyone else is out with a medium to larger aperture scope and can confirm or deny Mimas, I've be very interested to hear from them 🙂

I am using the slow-mo's on my Skytee II with the ED120. Mind you I am observing at 300x plus currently. The Rowan's are superb mounts though. Quality just oozes from them 👍

Similar with my Nagler 2-4 zoom tonight. I think I've had glimpses of Mimas (mag 13) at 360x with the ED120. Chuffed if that is the case 🙂

Tele Vue have a parfocal group called "B" and quite a lot of their eyepieces reach focus there - it's about 8mm further out than many other brands of eyepiece (eg: Pentax XW's). TV plossls, Radians, 1.25 inch Panoptics, T6 Naglers, Nagler zooms and a few others are included in this group.

And of course I forgot in the dark to take the aperture mask off and tried Lambda Cygni...... 🙄

Are we going down the "no undercuts" path then ?

I'm just waiting with my ED120 for it to rise above the roofline. Thanks for the appetiser 🙂

Does this help ? The full set of this range and therefore the best one in it 😁

Just tried this. At 53mm / 225x (Nagler zoom at 4mm) I got a large airy disk for the primary star with a very thin and faint diffraction ring and just on the outside of that ring, the faint secondary star. A definite split though. This is a very regular spring / summer / autumn double for me though so it helps to know exactly where to look for that dim secondary. No doubts about it in my mind though. A split with 53mm of aperture. Probably very good seeing tonight so looking forward to Saturn at full aperture with this scope 🙂

Fascinating mounts those. Ultra simple but clearly beautifully made and they handle surprisingly large loads.

Which is most divergent ? Hmmm ...... I'll have a think about that. This thread is TOO addictive. My other half has reminded me that it's my turn to make supper - I'll have to catch up later 🙂

A small detail that I had conveniently overlooked 🙄

The ones I'm talking about look like this:

I have owned the 5mm, 7.5mm 30mm and 35mm Ultimas and an Orion 10mm Ultrascopic (the Japanese made ranges). This was a long time ago now (20+ years) but I do recall thinking that they were very good and liking the 30mm best of all. The 35mm was excellent and quite spectacular with all that glass in a 1.25 inch eyepiece but it's focal plane position meant that I could not bring it to focus in some of my scopes, which lost it some "brownie points" mostly out of frustration !

In lieu of a reply from Don, the optical design and performance diagrams below for the Pentax XW range show quite a variation in optics and performance characteristics across the range of focal lengths (the latest 85 degree ones are not included). Some of the focal lengths do better with certain scope types and some will appeal more to the observer depending on their preferences. It's quite complex Other brands / ranges have similar variations. Some ranges use what is known as a "scaled" design which is basically the same for each eyepiece in the range but with smaller modifications, lens spacing, etc, etc to deliver the range of focal lengths. With these scaled designs I guess it's quite possible that one or two focal lengths are optimal for the design and the manufacturer accepts minor compromises in other focal lengths in return for manufacturing simplification.

I believe they are the same.

We are going to end up with a set that will drive folks with a touch of OCD nuts 😉

When I tried my first XW (the 10mm, loaned to me by FLO) I didn't like it at all. Then I read the instruction sheet ................. 🙄

They are different and I know which I prefer 🙂

I thought XW's were, generally, glasses-friendly eyepieces ?

I think those who need to wear glasses when observing are going to have some different favourites from those who don't. Some overlap as well of course 🙂 I liked the TV 32mm plossl when it had the eye cup extender fitted. Without that, I found holding the eye position tricky because the stock eyecup is not quite long enough. Someone who wears glasses would much prefer the eyepiece without the extender I'm sure.

I've seen Enceladus with 10" and 12" inch scopes and I think I managed it with a 6" refractor when I last had one of those. I've not managed it so far with anything smaller but to be fair I've not really tried hard to seek out the favourable elongations for the moon. I've had to take the views when they have been available with the mixed summer this year ! I tried with my ED120 last time out but Enceladus was close to the ring system so not visible in that scope on that occasion. You probably know about this one but this tool plots the positions of Saturns brighter moons so you can see what might be possible and plan ahead: Saturn's Moons (skyandtelescope.org) Stellarium does the same thing of course.

I probably don't need a Uni 28. It's never used anywhere near it's full height. At the time I bought it I thought that I might have a really long refractor at some point but, so far, that has not happened.

That looks very similar to the Stellarvue Raptor 105 F/7 or is it a clone ?