John

Just picked up c2018 w2 Africano with my ED120 refractor. Just now it's in a triangle of mag 7 - 9 stars just above the circlet of Pisces bit wont be there long - it's moving rapidly. Certainly brighter than my last sighting because I found if fairly easily with the 4.7 inch aperture at 43x. The comet stood out from the background better with a bit more magnification though - around 80-90x seems useful. It's currently around 75 million KM away from Earth apparently. Edit: I've been comparing the brightness of the comet with the galaxy M110 in Andromeda and I reckon it's a touch fainter than that. I reckon magnitude 9.5 would be about right ?

The original poster is in Australia so Jupiter will be high in the sky there. Unlike here in the UK I understand that the image was simply used to illustrate the issue - it's not one that the OP actually captured.

Lots of good advice here. I have seen an image just like the one you post very occasionally with my 12 inch scope. What caused that for me was either a fogged eyepiece because it got too cold and fogged as my eye approached it and also, once, a dewed up secondary mirror but I've only had that on a very peculiar night weatherwise. Normally my primary and secondary mirrors stay clear. To stop my eyepieces getting too cold and fogging I keep them just above the outside temperature and that does the trick. A foam lined eyepiece case helps because the foam retains some warmth for some time. An out of collimation scope does not show quite what your image pictures - if the scope is out of collimation the contrast and detail on the planet is reduced / harder to see but the hazy halo effect you show is not collimation-related I feel. It looks like classic fogging / misting of an optic to me.

My cases were quite cheap - I got them in Maplins sale a few years back. About £15 each I think. The contents cost a fair bit more though .......

I agree with this having owned and used both BST's and a couple of the Hyperion zooms. What you gain is the convenience of the instantly variable focal length rather than any notable optical improvement. You would still probably want a low power / wide field eyepiece as well as the zoom though - at 24mm setting of the zoom has a rather narrow field of view (in common with most zooms). To get a step up from the BST's you might need to think about Explore Scientific 68 or 82 degree ranges, Nirvana 82s or even the Tele Vue Delos or Pentax XW's if you really want to push the boat out and let your 14 inch dob really show what it can do.

My society tries to offer public sessions at our observatory a couple of times a month from October through to around June but the reality is that more than 50% of these get scrubbed due to poor conditions. If someone was relying on such sessions for their observing then they might only get a handfull in during a year, at best. As Iain says, a spontaneous approach with your own gear at or close to home will usually deliver much more observing.

You should do some more scope and eyepiece reviews Piero - your eye is clearly very well tuned for spotting these aberrations

I'm motivated to have another try at this one now ! I did try once but found it hard to track down due to how far from the visible core of M31 it is (as Neil says). These observation reports and sketches are very helpful for aspiring Mayall II observers !

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 ?