John

I've used one of the Skywatcher 150 F/5 newts on an AZ-4 mount head and it worked pretty well. A Giro or a Sabre would be more than adequate I'd have thought. The AZ100 would be overkill (but in a lovely way !) IMHO

Spinal Tap ?

Some more great points of view have been posted in this thread. Thanks very much for contributing what you think folks I didn't set out to start an observation vs imaging thing of course. Whatever floats your astronomy boat is good with me The majority of members of my astro society don't image or observe but I enjoy meeting and talking with them anyway.

Sorry folks. I have checked the contents of the packages (all fine) but I've had no chance to assemble and play with anything due to extensive DIY work going on here. I'll try and get some photos taken when I get a chance. Weather forecast looks poor so actually using the mount may have to wait a bit longer.

...... and then a coma corrector because the better corrected eyepieces will allow the coma that the scope produces to be seen more readily

Looking at your eyepieces (assuming these are what you are using) you might be seeing astigmatism rather than coma. Coma will also be there but eyepieces that stuggle with the F/4.5 focal ratio will show astigmatism in the outer field of view which tends to mask the coma and/or combine with it. A coma corrector will tighten up edge of field views by controlling the coma but won't address eyepiece astigmatism if that is the primary cause of what you are seeing. Some more info here on these issues to help you decide what the issue is: http://umich.edu/~lowbrows/reflections/2007/dscobel.27.html

Thanks for the link - I'll have a play with that I believe it's really called Barringer Crater after Daniel Barringer who was the 1st to propose that it was created by a meteorite. It has also been known as Canyon Diablo Crater after the narrow, sinuous dry valley that winds across the plain nearby. The meteorite that created the crater is still known as Canyon Diablo. The Barringer family still own the crater and some land surrounding it and operate the visitor centre and access to the crater. Frankly for $18.00 I thought it good value but then I'm into astronomy

Which flare outwards towards the primary I seem to recall so they would be the true secondary obstruction of the scope I suppose.

Good point from Steve regarding the status of the mount that I have been sent. I will repeat it when I'm posting on the mount to avoid any confusion. I'm pleased that Stu will have a crack at it too - his experience and enthusiam for the technology side of things is much greater than mine I'm unwrapping the mount and other accessories now and will post some photos and initial reaction ASAP. Many thanks to Rowan Astronomy and Steve / FLO for trusting me with the inital "tyre kick" of this product

Nice specimens of Sikhote Alin folks. My own bit looks more like Debo's to look at but a smaller piece. I used to have a wonderful 200 gram chunk of SA with reglamypts, a roll over lip and other flight markings. I sold it a few years back to buy more astro stuff though I've been building up another meteorite collection recently - I'll have to post some pics. I'm up to 20 different types now.

Thats good to know Chris. It must have been the earlier ones that were working at less than full aperture. Neil English was convinced that his (branded Orion USA) was nearer to 170mm and referred to it was such in his review of the scope. This is an extract from that review: "It was discovered that the effective aperture of the large Orion Maksutov was nearer 170mm than 180mm. I was alerted to this after performing double star tests earlier in the summer of 2014. When I observed Zeta Herculis, I detected the faint companion to be located on the first diffraction ring of the primary star. Now, the locus of the first diffraction ring from the Airy disk is 185/D where D is the aperture in mm. The latest information on its angular distance from the primary is 1.1″. Something interesting occurred to me when I set the formula to find D for a 1.1″ separation. Thus 185/1.1 yields 168.2mm. Then I remembered a review on a lady’s website from the UK where she talked at length about the same (albeit Sky Watcher incarnation) telescope and reckoned the actual true diameter was nearer 170mm than 180mm; "Subsequent flashlight tests confirm that many of the Synta/Orion Maksutov have slightly smaller apertures than advertised (the 127mm model being closer to 120mm). This is due to the fact that the primary mirrors are the same aperture as the corrector plate which results in slight internal vignetting. In comparison, the older Meade 7 inch LX 200 Mak as well as the Questar 7 have an over-sized primary mirror to correct for this." Presumably Synta must be incorporating a larger primary mirror with the later models ?

Thanks Steve, It was great to bump into you and your other half at the Lowell Observatory. That was another place that I'd wanted to visit for many years

Hi and welcome to the forum The focus on a finder is usually adjusted as per the movie that Knighty2112 has posted. The standard 50mm finder on the Orion XT10 is a stright through unit I think - the 45 degree prism / eyepiece is likely to be a later addition. If the 45 prism / eyepiece has been added to a stock straight through finder then that might be a reason why the finder will not come to focus.

Are the Skywatcher mak-cassegrains operating at full aperture these days ? Their design used to mean that the effective aperture was a bit less than stated so the 180 was in fact a 170 etc etc. I had a Skymax 180 for a short while but found the cool down time too long for my observing circumstances.

You can always experiment with a cardboard mask with a hole the diameter of the clear aperture of a 1.25 inch filter cut in the centre. Put that on the end of the eyepiece barrel and see what the effect on the AFoV of the eyepiece is.

Thanks. There is a nice and newish visitor centre and museum which leads on to viewing terraces on 3 levels and there is also a walkway partway around the rim. To get down to the crater floor is a 2 hour hike in very hot and rough conditions. Only allowed by special permission. As you approach the crater (the pic below was taken from around 3 miles away) all you see are the low crater ramparts, no suggestion of the massive pit of the crater which is 1200 meters across and 175 metres deep. All created around 50,000 years ago in around 10 seconds by an iron meteorite estimated to be around 150 metres in diameter. Must have been quite a BANG !!!

Seems a long time ago already but a month ago I visited this place which has been on my "must do one day" list for many years. Very much worth a visit if you are ever in northern Arizona

I'm going to spray my Skytee II black, pop it in the AZ100 box and hope they won't notice the difference ........

I believe so. I'm expecting this setup when I unpack the packages on Monday. Plus a Berlebach Uni 28 tripod, a power supply and a Losmandy plate to attach the scope that I'll be testing the mount with. What nice people they are

The coatings on the lenses could get scratched and that would notably devalue the eyepiece if you ever want to sell it, although it would still work fine.

Personally I'd not use the encoders or the Nexus DSC unit so I hope the mount functions well without them. I'll find out early next week when the only AZ100 yet in existence (complete with encoders and the Nexus unit) arrives

As long as the filter does not touch the top lens (as Ben warns above) it does actually work. One technique of finding challenging nebula is to move a UHC or O-III filter in and out of the view though the eyepiece and see if the nebula can be spotted "blinking" on and off. An issue that I've found when I've tried this is that the filter gets in the way of putting the eye at the right distance from the eye lens (ie: the eye relief distance) to enable the full field of view to be seen. Also the filter glass seems to attract annoying and distracting glare and reflections from any light sources nearby more readily than the eye lens of the eyepiece does.

If you just want the standard item, here is one on e.bay: https://www.ebay.co.uk/itm/Skywatcher-2-Eyepiece-Adaptor/223692961084?hash=item341523b53c:g:L-MAAOSwavRdl4q5 Edit: Now you have 2 options in 25 minutes. Not bad !

I saw that one. I know the seller - top chap and very knowledgeable I was briefly tempted because the scope will be in good shape and is a little bit of history in its way. Nowhere to put the thing though !

I bought my used Nagler 31 around a decade ago and I expect I could sell it for more now than I paid for it back then. If I decide to sell my Ethos eyepieces (all bought used) I'll get my money back there as well I reckon. Until light pollution gets to the point where nobody can do un-aided visual observing that is, after that they will just be paperweights and curiosities !