John

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.

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.

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.

What matters is where the laser exits the objective. Don't worry about what it looks like when it hits the wall / floor / whatever. The tilt of the objective (stage 2 of the checks) is done with a cheshire collimating eyepiece, not a laser collimator. The last 2 photos posted by jock1958 show the the view through the cheshire collimating eyepiece when the objective tilt needs adjusting. You should see a single illiuminated disk rather than the 2 partially overlapped ones. Just to re-iterate, there are 2 stages which need to be carried out in sequence and 2 tools involved: 1. Check and adjust (if needed) the focuser alignment with the objective optical axis. This is done with a collimated laser collimator. 2. Check and adjust (if needed) the tilt of the objective lens. This is done with the cheshire collimating eyepiece. Where there are no collimation adjusting screws (very common), you can apply some tilt to the focuser by loosening the screws that hold it onto the scope tube and adding a shim or two to one side to tilt it slightly. Then tighten up the holding screws. If the objective tilt is out then things are more tricky but there are some tricks which can help.

I'll be going but I'm not sure of which day yet.

1. The scope comes with two 'adapters' that I need to put ion the scope before I can attach the eyepiece. Should I use both the adapters? This will increase the focal length and therefore magnification? Or better to just use one adapter then add the eyepiece? I definitely need to put one on, or the eyepiece wont fit.. I'm confused why there are two though. One adapter allows 1.25 inch eyepieces to be fitted, the other 2 inch eyepieces. You should use only one at a time. If you use both adapters, eyepieces will not come to focus. 2. It came with 25mm and 10mm eyepieces. Would you recommend a 5mm or barlow or something also? If so, which ones are a good choice? A 2x barlow lens is a good way to double up your eyepieces, the 25mm becoming 12.5mm in the barlow and the 10mm, a 5mm. The standard Skywatcher barlow (the deluxe achromatic one) is not bad quality for what it costs. A 6mm eyepiece is also a very useful focal length for the 200mm F/6 dobsonians - it gives 200x which is a bit more useful than the 240x that the barlowed 10mm eyepiece gives. 3. Is it really that important to get the scope to ambient outside temperature before use? I'm using it in my bedroom with the window open. Ideally it's best to use the scope outside and when it's cooled to outside temperature. Inside a house you will be viewing though heat thermals coming out of the window which can degrade the views at higher magnifications. 4. Can you recommend a good collimating device!? I use a simple cheshire eyepiece like this one: https://www.firstlightoptics.com/other-collimation-tools/astro-essentials-cheshire-collimating-eyepiece.html

The way that I do it is to remove the diagonal, put the laser collimator (which has itself been well collimated) in the drawtube and turn it on. At the other end of the scope, see where the laser beam exits the objective lens. If it is right in the center, the focuser optical axis is aligned with that of the objective, if the laser exits off centre, the focuser is tilted to some extent and it's opical axis is not aligned with that of the objective lens. I don't use the angled target face of the laser collimator at all for this test. To test the collimation of the laser collimator itself (which is importan as thay can often be out, especially with low cost units) I use this method: http://www.stark-labs.com/craig/llcc/llcc.html

I do have a TMB/LZOS 130mm F/9.2 triplet Alan - it's very close to the same weight and length as the ED150

My 12 inch F/5.3 Orion Optics dob weighs around the same as a Skywatcher solid tube 10 inch dob. I can move my 12 inch around in 2 parts pretty easily. It's almost a "grab and go" scope actually

For a long time I eschewed scopes with apertures smaller than 100m because I simply found that they did not deliver views that were satisfying even if they were portable and quick to setup. Over the years I've owned a number of ST80 achromats, an ED80 and a William Optics 70mm ED doublet. A while back I picked up a used (quite old actually) Tele Vue Ranger 70mm and found that a really nice little package to use. It actually helped me out of a period when I lacked enthusisam for observing because it was simply so quick and simple to pop out and look through. The Ranger weighs just 1.6kg and I've got it on a photo tripod and Universal Astronomics Dwarf Star mount which together add 1.7 kg so the whole package is just a bit over 3kg - literally a one hand pick up job ! I've had some very enjoyable sessions with this scope since I've had it but I've not taken in travelling so far, despite its light weight and compact size. When I've travelled in the UK I've usually been able to squeeze a 100 / 102mm refractor and mount into the car and, so far, I've restricted myself to binoculars for trips that have involved air travel. The latter decision is mostly influenced by not wanting to inflict my hobby on my other half when we are on holday though - she gets enough of that when we are at home ! So I have now discovered the joys of a small and highly portable scope and where it fits into my hobby but travel has not really been the driver behind this as much as sheer convenience and the ability to have ad-hoc observing has. It might also be that my outlook on observing has changed in the past few years as well so that I appreciate what a small aperture scope can do rather than being frustrated by what it cannot

Great report on the big Panoptic I have the (by comparison, miniscule) Panoptic 24mm and enjoy it a lot. Most of my low power viewing with my 12 inch dob is done with my Ethos 21mm and, less often, with the Nagler 31. I find that the 21mm gives a darker background sky because I have a little light pollution here to contend with. Thats why I don't use a 40mm often so the Aero ED 40mm will do fine and I doubt that I could justfiy the additional cost of the 41mm Panoptic given the amount of use that it would get

Thats good news Doug and I'm very heartened by the overall response to this thread from SGL members