John

That might be the sort of plan that I follow. Much easier to get my 11x70's to a good vantage point and they should show the two planets plus the Jovian moons quite well.

The planets should look something like the images below (excluding the name labels !) through the scopes being discussed here at around 200x magnification. Small but sharply defined disks. The detail visible on the planetary disks / rings will vary depending on the seeing conditions. Experienced observers spending time at the eyepiece can usually pull out a bit more detail. These assume a cooled scope that is in reasonable collimation. Saturn might not show all the moons in the image below - some are faint and hard to spot. These are not exact simulations but in my experience you should be getting something along these lines:

Same here

LZOS objectives often show as a touch better than the manufacturers supplied tests, when they are tested independently. The manufacturers test is just to demonstrate that they have met the minimum standards required I believe. This is the specification that APM agreed with LZOS for the supply of objectives: APMApo-Linsen-Spezifikationen.pdf

What an incredible place - thanks for posting the link

I have a few hills around me with a clearish and lowish SW horizon. From home though that direction is obscured by all sorts of things. Already Saturn and Jupiter are more or less un-viewable from home. Marks idea of "bracketing" either side of the 21st is sensible given the weather we get. With the targets so low down I will probably use a refractor both to cut through the atmosphere and the ergonomics of the instrument (on a tall tripod) makes getting onto targets close to the horizon a bit easier. The 12 inch dob is not an instrument to cart up and down hills either !

Thanks for explaining that. The test on my 130mm refractor was at 532nm which is green I believe. Polystrehl ratings are talked about quite a lot these days but you hardly ever see test reports that cover this. I have seen drawings of those string tubed refractors before. It would be fun to make one if the space was available ! That is a very unusual looking scope you have. It reminds me of a design that Istar used a few years back:

I find around 200x / 265x works very well on globular clusters with my 12 inch dobsonian. Good for planetary nebulae as well or even higher magnifications for the small planetaries.

Also, what has this to do with strehl ratio ?

Well, for nighttime observing I've found that light shrouds are needed otherwise the wonderful optics show lowered contrast due to ambient light intrusion. The solar image you post are H-alpha I believe - what H-a filter do you use to get them ?

This thread is 14 years old ! I'm amazed that the mount, and EQ5 clone, handles such a large, long, heavy optical tube Amazing images though !

Must try and find somewhere which gives me an uncluttered view to the SW. Saturn and Jupiter will be really low down from here on and around that date / time.

If they had the better spec lens retaining ring fitted and the collimation checked and adjusted as needed, they would have been good scopes.

Glad you got it sorted Michael I find blurry field stops quite annoying. They don't really impact the performance of the eyepiece but I still find them annoying. The Baader Classic Ortho 6mm had this issue but I could not sort it out because the field stop on that eyepiece is machined into the lens retaining ring. Loosen that to put the field stop at the correct (sharp) position and the lens elements rattle

Good improvement there as well. I wonder what happened to the 2 scopes that I was loaned

No - just some strips of styrofoam across the top and bottom of the case (not the sides)

Interesting to compare the internal case packing that is now used (1st pic - Garry's) with the 1st one that I was sent (2nd pic). Subtle but effective changes. The scope case is also protected within the cardboard box by whole sheets of foam rather than a few spars of foam that were used when they sent mine:

The examples that I was sent were very, very early ones and the manufacturer and importer have reacted positively to the early issues. Even back then I felt that the scope had great potential to be a larger aperture version of the excellent ED120 Pro and that is what it is turning out to be Here is one of the ones that I had compared with my ED120 for size:

Actually that might be so. I'll see if I can find it.

Nope - a big one of these

A double star was one of the very first things I observed with a telescope. This was about 40 years ago and the star was Algieba, Gamma Leonis. I managed to split it with my old 60mm Tasco refractor at 133x and was chuffed to bits Glad you have discovered these wonders at last Marv

In the USA they do a "de luxe" version with CNC rings, losmandy DT bar and Esprit focuser called the Evostar 150ED DX. In Europe the bar and rings are available as an add-on pack but not the focuser as far as I know: https://www.skywatcherusa.com/collections/evostar-ed-doublet-refractors/products/evostar-150dx-apo-refractor

That looks a familiar line up I use 6mm and 5mm quite a lot with my 12 inch dob. 4mm down to 3mm with my refractors as well.

Mark had the F/10, I had the F/12. They were monsters. There was an F/15 in the van when my scope was delivered - the box seemed to go on for ever !

This is the only pic I have of me with any of my telescopes. It was taken about 3 years ago: This is my 1st "proper" telescope, purchased in around 1984: