John

I'm surprised to hear that. I've seen other issues such as field curvature with refractors but never coma. https://starizona.com/tutorial/coma/

Coma in a refractor ? - I thought it was a reflector thing ? On coma af F/5.3, I tend to take the view that if I don't see it, and I do look from time to time, it's not going to bother me I've often followed a binary right across the field of my 6mm Ethos (265x) and it's remained sharply defined and split until it slips behind the field stop. I can't ask more than that

I see very little, if any, coma with my F/5.3 12 inch, even with the Ethos eyepieces. I guess it's there but at a level that is not significant, at least to my eye ?

Thanks I have owned the Leica ASPH zoom for a while and it was very nice but I decided in the end that it was not for me. I know other folk who feel that its a "must have" eyepiece so it must be my odd tastes

I keep mine capped and in foam lined flight cases. My cases are the plucked foam ones from Maplins but they have gone out of business now. I'm sure something similar is availabale elsewhere.

I think the Giro Ercole uses a sensible approach to the counterweight bar fitting. The steel alt axis is drilled and threaded to accept a 10mm screw which is what the C/W bar screws into. The end of the steel axis is recessed within the machined alloy arm and the C/W bar slides into a 20mm diameter sleeve in the alloy arm end and then screws into the alt axis. So the C/W bar gets support from around 50mm of precisely machined alloy sleeve as well as being screwed firmly into the alt axis. The Altair Sabre mount uses a similar approach to C/W bar fitting.

Maybe on the latest Skywatcher focuser designs but not one the older ones. It's a rather odd and annoying design that Skywatcher went for back then - other brands gave you a 2 inch drawtube with a 2 inch eyepiece fitting on the end of it then you use a 1.25" adapter when the smaller eyepieces are in use. Skywatcher decided that you would need to use an adapter for both eyepiece sizes (used separately) so their drawtube has an adapter that is a touch over 2 inches in internal diameter and that needs a flanged adapter fitted into it to house the eyepiece. Maybe they have seen sense more recently and adopted the approach that other brands have always used ?

Actually I think low light scatter around bright targets at medium to high magnifications is quite an important practical characteristic. Light scatter is one of the issues that can actually make seeing certain target types eg: faint planetary moons and very uneven brightness binary stars, somewhat more difficult or even impossible if it is extensive.

I used to have one of those - I used it with my old Ambermille (anyone remember them ?) alt-az mount. It worked well but I didn't put more than 5kg on it.

I agree - the 10mm and 18mm Baader Classic Orthos are superb - possibly the best optical quality eyepieces that you can buy for under £50. They don't have the wider field of view of the BST Explorers, the exterior gloss or as much eye relief but their sharpness and light throughput are really top class.

Was that with the F/4 20 inch Mark ? Are you going to use the Paracorr with your 12" Revelation F/5 ? It would be interesting to see how much the slightly slower focal ratio benefits from coma correction.

Same here. Is there an adapter or will I need a new hub section ? Edit: Don't want to derail this thread into a Berlebach tripod discussion - I'll pursue this elsewhere. It is a really good looking mount Grant

I've been interested in the AZ8 for some time and very nearly bought one but from the feedback that I could gather on it, I had some lingering doubts whether the AZ8 would carry my F/9.2 130mm triplet refractor more steadily than my Skytee II currently does, which would be the prime reason for me to acquire such a mount. Of course the AZ8 is much better machined and finished than the Skytee II, that is obvious

Thanks Grant

With a couple of DT clamps the AZ100 will be pretty much the same price as the AZ8 I think. It's the capacity to handle tube length that I'm interested in

Does the AZ8 cost of around £1K include DT clamps and a tripod ?

Lovely looking mount Can I ask if a dovetail saddle for the AZ100 will available in the Vixen fitting as well as the Losmandy D fitting ? Can other makes of DT clamp be fitted to the mount ? Also, as per Omo's question above, what is the tripod fitting ? Many thanks

I think jock1958 is simply using the mirror on the floor so that he can see where the laser is exiting the objective and the paper target from the focuser end of the scope ? I'm not sure that he is using the mirror on the floor as part of the collimation system apart from the above ?

I've owned a few Meade 3000's and thought them great as well. Better than the 4000's IMHO, I've had a couple of mediocre 4000s over the years. Piero mentions using a 2.25x barlow with the 11mm TV plossl. That will have the effect of increasing the eye relief a bit of course.

Solid clouds for the past few days here too. Looking forward to viewing Africano again if we get a clear patch. Good that its brightening. When I first observed it I thought that it was below the billed magnitude and was going to be a damp squib but hopefully it will be a decent one. Glad you have had some good sightings Neil and Mark, hope you get to 1st light the 6mm Ethos soon

I've owned a few barlows and some Tele Vue Powermates. The Powermates are superb in my opinion. They just seem to be invisible in the optical train apart from amplifying the image. Your SN-10 is an F/4 I believe ?. F/4 is very challenging for eyepieces that have wider fields in respect of maintaining sharpness across the view. Tele Vue have made this a strength over the years. Be prepared to spend as much or more on eyepieces as you have on the scope though !

The TV plossls have really good transmission IMHO. I saw some data a while back resulting from throughput tests and the TV plossls were a bit better even than orthos (both classic and top tier HDs).

So you are both enjoying yourselves ?

I'm pretty sure that the TV plossl is a symmetric. I've seen the optical diagram on the TV patent and it sure looks like a symmetric. I've taken a few plossls apart over the years (not TV ones) and those have had what looked like 2 indentical doublet elements in them as well. Some of the older Vixen orthos also use the same design I was surprised to find, rather than the 1+3 abbe type ortho design that I had expected. I believe the feature that enabled Al Nagler to get a patent on his plossl was the curvature applied to the outer two lens surfaces which improved edge correction as I understand it. There is a rumour that Vixen NPL's use a similar design. On the 11mm TV plossl, I've owned a few over the years and found them sharp and contrasty. The eye relief is limited to around 75% of the focal length as it is with all plossls. The stiff rubber eyecup that TV use on the 11mm plossl can make accessing the full field of view a little tricky.