John

Thanks for the reminder - I've just managed to pick that comet up with my 100mm refractor. Quite hard work given the conditions tonight ! The Orion part of the sky looks a bit better than other areas so there is hope there, once it has risen a little higher.

Seeing still not good here. Theta Aurigae is split at 225x by the 100mm refractor but not in the usual clinical way. Defocussed star disks show plenty of disturbance even though the scope is entirely cooled. Bands of cloud now also putting in an appearance. I'll give it a bit longer but it's certainly not going to be a classic night Obviously Derby is the place to be this evening

It was mediocre here earlier. Still clearish though so I'll give it another try and see if things have improved. The transparency is not good so if the seeing is still poor as well that doesn't leave a lot of options

Interesting report Baz "....the view was equally as good as the ED or possibly slightly better...." That caught my eye. Can you be more specific ? Resolution, contrast or something else ?

Usually, with Skywatcher newtonian focusers, you use the 1.25 inch adapter when using eyepieces of that size or the 2 inch adapter when using 2 inch eyepieces. Focus issues are often caused when both these adapters are used at the same time (ie: 2 inch adapter > 1.25 inch adapter > 1.25 inch eyepiece). At least that how it's been in the past and the solution has been to just use one adapter or the other. What can add to the confusion is that when you use both adapters you can actually get the scope to focus on terrestrial objects that are relatively close. It is when you try and focus on an astronomical target that the focus can't be reached. Maybe Skywatcher have changed the design of their focusers recently though ?

Looking at that photo again, I agree. Those truss tubes do need to be fully extended. Good spot @almcl I misread your post and thought you were referring to focuser tubes

While there were some clear patches low down towards the west from here earlier, there was a long thin bank of cloud right along the horizon in that direction which I suspect provided a hiding place for Comet Leonard. So still no sighting of it for me

I wish I've never seen one outside of a catalogue.

The focuser drawtube is racked all the way inwards in the photo that has been posted.

I think it is the opposite - you need to use either the 2 inch or the 1.25 inch adapter, but not both together.

As above - the dual axis kit's top speed is 16x whereas the SynScan EQ5 can slew up to 800x. In practice, with the dual axis kits, slewing is done manually and then the drive speeds are used for centering the target.

I'm with you on this. While I have 4 really excellent refractors from 100mm to 130mm in aperture, it is my 12 inch dobsonian that has given me the most "wow !" moments and the most "firsts" during the decade that I've owned it. And my 12 inch dob (also an OO) is as quick to setup as the refractors as well

One thing that I've noticed is that the characteristics of one eyepiece might make it a champion on, say, Jupiter while another is a little better suited to, say, Mars. Of course this could just be an excuse to own a wide range of eyepiece designs at short focal lengths. Any excuse will do !

It's sold now but this long 8 inch newtonian caught my eye recently. Local to me as well: https://www.astrobuysell.com/uk/propview.php?view=180708

The french magazine "Ciel et Espace" used to do really detailed and rigorous comparative tests of eyepieces which included an array of optical tests, light throughput tests, spot testing etc, etc. They stopped those some time back unfortunately - perhaps some of the "runners up" brands decided not to play ball any more !

There have been tests of eyepiece transmission from time to time in the past. This is rather out of date now but covers a few types: Eyepiece(1).doc As Gerry / jetstream says though, this is less critical for planetary / lunar observing.

I've found Jupiter better this year than last - hardly any AD. Saturn is lower so a little more affected by it.

Get the refractor AND a nice dob

Well that's the thing isn't it. The difference in price can get you a nice 10 inch dob AND some nice eyepieces and a lunt solar wedge to add to your fine 4 inch refractor so you can have an observational setup that can last a lifetime for the price of one "poodle".

From the Ohara website: "In the course of Ohara’s long history, many types of optical glasses have been developed. In this catalog, you will find over 130 glasses which we have selected as our “recommended glass types”. Each optical glass has its own properties which are closely connected with the key chemical element it contains. With this in mind, we have developed a new glass type designation system and the new names are used in this catalog. On the nd/vd diagram, located on the Optical Catalog webpage, you will see we have divided our glasses into groups. For each glass type, we have selected on or two chemical elements contained which are considered the most important and have used the atomic symbols of these for the first two letters of the glass type designation. The third letter of the glass type designation refers to the refractive index of each glass type within its glass group: H, M, or L for high, middle, or low. Lastly we assign a one or two digit number to each glass type within a given glass family. Thus each glass type is represented by the above-mentioned three letters plus a one or two digit number. We are also adding the prefix “S-“ to indicate which of the glass types are ECO optical glasses and environmentally “Safe”. These glass types do not contain any lead or arsenic. For example, the glass type designation for S-BSL7 is composed as follows: S- stands for environmentally Safe B represents Boron, one of the key compositional elements S represents Silicon, one of the key compositional elements L indicates a Low index within the BS group 7 indicates this is the 7th glass within this glass family Along with Ohara’s glass type designation, the technical data sheets will show the six-digit code for each glass type. In the six-digit code the first three digits represent the refractive index at the helium line (nd) and the last three digits represent the Abbe number (vd). These six-digit codes are internationally recognized within the optical community. So we just need to work out what the F and P stand for.

The announcement of this Starfield 102mm F/7 was one of the main reasons that I started my recent thread "Why do really expensive scopes sell ......". Starfield 102mm F/7 = £899 Takahashi FC100-DF inc tube clamp = £2,300ish. £1,400 is enough to make me think very seriously about that !

Same source as my info I expect

In 2017 Ohara FPL-53 was priced at 18x as much as BK7 crown glass. FPL-51 was 11x as much as BK7. That was from an Ohara price list. Apparently at that time Fluorite cost an eye watering 75x as much as BK7 I don't know if those relative costs have changed now or not.

I suspect it was atmospheric dispersion. An achromat of around 50-60mm diameter at F/19 should be colour free to all intents and purposes:

Similar although the other way around - things started a bit fuzzy (poor seeing) but got better as the evening went on. Trouble was, most of the visitors seemed to run out of steam after an hour or so. We spent the last 30 minutes just comparing the views in our scopes. As my scope was cooled I set it up again when I got home and had another hour on various targets before the clouds came across. I think the visitors to the outreach session enjoyed it but I think some might have wished that they had worn another layer or two I really enjoy sharing the views through a scope with others - it's the thing I missed the most in astronomy over the past 18 months when we could not do it. I'm glad yours and Xgaze's sessions went well Whenever I'm doing some outreach and sharing the views John Dobson's words pop into my head that the most important thing about a telescope is how many people other than the owner, get to look through it