John

These are all the flanges that Moonlite do for various refractors. My suspicion is that they won't have one currently with the Bresser AR127L name on it but one of the others is probably the right one, either a Meade or an ES probably because those brands have had strong connections with Bresser products. The question is which one precisely ..... https://focuser.com/refractorflange.php If you can get the flange sorted out, the rest is easy

The Skytee II should handle an ED127 triplet OK if it is on a sturdier tripod than the stock 1.75 inch one. A 2 inch steel tube legged tripod or even better a Berlebach Uni should be investigated. Even then you would probably have some vibrations to deal with at higher powers I reckon.

In my opinion a 100mm ED doublet would have the edge over an ST120 for white light solar observing with a wedge. I use my Lunt wedge with my Vixen 102mm ED and Tak FC 100 and the results are really good. On double stars I think it would be a close run thing but personally I feel that good ED doublet refractors have provided the most satisfying views of double stars of any scope types that I have used. On lunar observing, again it would be a close run thing between a good ED 100mm doublet and a 127mm mak-cassegrain.

A quick "bump" for this heads up. More info on UK observation here: https://www.popastro.com/main_spa1/transit-of-mercury-2019/

The trouble is that the GOTO function eats up a lot of a £350 budget leaving proportionaly less for the scope itself wheras without GOTO that budget would get you firmly into the 200mm aperture class. It's a tricky decision I grant you.

Interesting thoughts Doug Lots of clouds and rain do tend to prompt this sort of review. That, and lots of equipment tinkering ! The only thought that I have to offer currently is that refractors seem to get quite a lot larger and harder to mount steadily when they exceed 120mm in aperture.

Yes, with an eyepiece. I've not actually used one though but I've read about the need for quite a lot of inwards focuser travel with this coma corrector frequently.

That still looks quite a large CO though ?

I agree with Dave - for purely visual observing I would always prefer to have that additional 22mm aperture.

Do you include imaging as a potential application for the scope ?

I don't feel the need for a coma corrector but I have read that the ES one requires 38mm of inwards focuser travel which has caused issues for some users.

Upgrading to the 1.75 inch steel tube legs tripod (who ever you buy it from) makes a lot of difference to the stability of the EQ3-2 mount I found when I had one. That alloy tripod is the weak link for sure.

Well, what do you know ? - the sky is clear !!! So the AZ100 is outside, has the 130mm F/9.2 refractor on board and I'm letting the scope cool for a bit before giving it a go

I won't know for sure until I actually use the mount but I'd guess that it would handle a 200mm F/5 pretty easily, also maybe a 250mm F/5.

More rubbish weather this evening so I've removed one of the dovetail clamps and installed the counterweight shaft and counterweight to see how that fits together. Four M6 bolts fit the C/W shaft to the axis once the dovetail clamp is removed. The C/W shaft mounting plate perfectly matches the full diameter of the altitude axis of the mount. The shaft itself screws into mounting plate with an M12 screw thread and that end of the bar is also enclosed in a snugly fitting 15mm deep sleeve. Its much more solid than I thought it might be and handles the supplied 5.2kg counterweight as if there is nothing on there ! The dovetail clamp is Losmandy fitting and a really nicely executed unit in it's own right. It is drilled with holes that fit a number of mount types in M6 and M8 sizes. I was pleased to find that it bolts straight onto the 35mm spaced M6 holes provided the Giro Ercole and Skytee II mount arms. With no scope to balance the counter weight the motion of the mount around both axes was just as smooth as it had been without the shaft and weight fitted. I'll actually get out and use the mount as soon as the clouds and rain relent. I'm very optimistic about it's likely performance from what I've seen so far Here are some photos of the mount with and without the counterweight shaft and weight fitted plus the rather lovely dovetail clamp:

I've read that a few times recently but I still see new designs with relatively large apertures coming on stream that use it so I guess reports of it's passing were exaggerated.

I suppose this topic also begs the question, what is serious amateur astronomy ? Someone at my astro society reckoned that you need to be an active member of the BAA to be considered a "serious" amateur. Maybe thats for a different thread though.

It's the small cheap scopes on e.bay that are labelled "Pro" than put a wry smile on my face Behind closed doors professional astronomers are all using those, of course

One thing that I've found about the dob mount is that they are really steady, in terms of vibration / shake control, when using high magnifications. Goodness knows what an alt-az or eq mount that would hold my 12 F/5.3 inch dob steady would cost or how big it would need to be but the simple plywood dob mount that Moonshane made for my scope a few years back holds it really solidly even when using 400x or more.

None of mine are serious - its a hobby for me and I do it for fun So Peter is probably right in that respect - it depends on the approach and attitude of the owner rather than the scope. When a look back at all the years of observing that I've done though, it's when I've been using my larger aperture scopes that I've been able to go deeper, look futher and see things that I otherwise would have found harder or not been able to see at all. So I guess currently my 12 inch dob is the nearest I have to a "serious" scope despite my lovely (and somewhat more expensive !) refractors.

The exit pupil does reduce as you suggest. I believe that coma is not actually changed because thats already in the optical system from the primary mirror which is still F/4 but sometimes it will appear a little improved because of the narrower field that the shorter effective focal length eyepiece delivers. Barlow lenses increase eye relief a bit too. There are one or two barlow designs around that claim to reduce coma (eg: the klee barlow) but I've not seen overwhelming evidence that they are effective. I've always thought that a coma corrector is either essential or very, very good to have if well corrected wider angle eyepieces are to be used to full effect in an F/4 newtonian.

This pre-production unit came with just one weight.

Ok, I've posted some initial feedback on the AZ100 mount here:

Due to one thing and another I’ve not had time to do more than unpack the packages that this kit came in from First Light Optics and this evening bolt a few bits together. Lots of boxes = lots of FLO’s “May Contain Clouds” stickers and, my gosh, that has proved to be the case so I’ve not been able to actually use this handsome new mount, yet. I must emphasise that the mount that I have been sent is a pre-production unit. The final item may vary in some details from the one that I picture and describe here and in my other reports. My very early impressions of the pre-production AZ100 are: - The AZ100 is significantly larger than both the Skytee II and the Giro Ercole. The pictures don’t really show how much difference there is but the whole mount is much more massive in all respects. - A quick and crude weigh in using a spring balance showed the AZ100 at 8.5 kg with saddles and slow motion controls installed. My Skytee II was at 5.2 kg and the Giro Ercole at 4 kg. - The fit and finish of the AZ100 is excellent. Everything fits together precisely and is machined to a really high standard. Both axes move very smoothly and are consistent in their feel. No sloppiness or jerkiness, just smooth progression around the axis. There are tension knobs on both axes which apply gradual and finely controllable tension. At full tension an axis is firmly locked but a quick twist of the knob and you have movement again. - The slow motion movement is likewise very smooth indeed. I could not detact any obvious backlash when I reversed the direction of travel but I was not looking though the scope at high power of course ! The slow motion control cables and knobs are high quality units and fasten to the worm shaft with 2 grub screws. On this pre-production version of the mount the end of the worm housing opposite the slow motion cable is open but I wonder if a rubber or plastic cover (removable for adjustment) might be a good idea on the final version of the mount ? - The Losmandy-type dovetail clamps incorporate 2 individually tensioned clamps on one side of the jaw with chamfered tips so that the dovetail bar is pressed back against the plate assembly as well as down into the fixed groove on the other side of the clamp jaw. Very secure, that seemed to me. - The knobs on the dovetail clamps and those that control the axis tension are excellent quality with a 5 star shape to give grip. I do wonder if they might benefit from being a little larger though, to help positive operation with gloved hands ? - I have unpacked the counterweight shaft and 5.2 kg counterweight and include a photo of those but I’ve not fitted them to the mount yet. The current design requires that one of the dovetail clamps is removed and the dovetail bar bolted on (4 bolts) in it’s place. The dovetail bar is 25mm in diameter, 28cm in length and it and the stainless steel counterweight are finished to the same high standard as the rest of the AZ100 mount. - My 130mm F/9.2 triplet refractor fitted onto the AZ100 easily and seemed to be very securely held in place. This telescope is 1.35 metres in length and weighs 9.9kg including the tube rings, dovetail bar, diagonal and finder. The true test of the mount will be it’s ability to hold this scope steadily at high magnifications when viewing the night sky ! - First Light Optics have also supplied me with a Nexus DSC Digital Setting Circle unit and a suitable power pack but I’ve yet to fit that to the mount. The encoders for this are already installed in the mount body. - Both the tripods pictured are the Berlebach Uni 28. Mine is the slightly darker coloured one with single leg clamps and an HEQ5 fitting. First Light Optics have provided an EQ6 compatible version of the tripod which is fitted with double clamps on each leg. The AZ100 mount fitted snugly and securely straight onto the EQ6 hub. - The combined weight of the Berlebach Uni 28 tripod and the AZ100 mount head is around 18kg. It is a well balanced combination though so I can move the mount and tripod setup around without too much trouble. With the 130mm refractor on board, it becomes somewhat more of a challenge but I think moving the whole setup short, level distances (ie: a couple of metres) is likely to be feasible with care. I apologise for the rather hastily taken photos that follow, taken in the rather messy setting of a dining room which is currently being re-wired and re-decorated completely. I’ve included the Skytee II and Ercole Giro in a couple of the photos to give an idea of the comparative sizes of these mount heads. More to come in due course including experience under the stars, hopefully in the not too distant future ! Many thanks to the folks at First Light Optics and Rowan Astronomy for allowing me to try this pre-production version of the AZ100. It seems to be a very impressive piece of kit with excellent attention to detail and a very high standard of fit and finish. Meanwhile outside, the rain pours down tonight so have a look at some pictures

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