John

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.

That is exactly what you need. You might need to try a "wanted" advert in our classifieds or on the UK Astro Buy & Sell website to see if anyone has one to spare.

I'd tend to go for a mirror at F/6.8. Thats what I use with my Vixen ED102SS F/6.5, Skywatcher ED120 F/7.5 and TV Ranger F/6.8. The Tak FC-100DL F/9 gets the Baader T2 Zeiss prism.

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

Very interesting thread this, full of good tips and techniques to push as deep as you can go I can recall the evening when I managed, at long last, to see the Horsehead Nebula. I found it an incredibly challenging target and one that pushed my ability and that of my scope to the limit I think. I spent a long time that evening getting fully dark adapted. Our house lights were all off and the neighbours were all in bed. The sky was very dark and transparent, as good as it gets here. I "warmed up" by observing faint deep sky objects using the views that I was getting of those to guage whether the Horsehead was likely to be possible. I knew exactly where the Horsehead is located and had familliarised myself with the star patterns surrounding it so that I knew my way around without needing a star chart and knew how those star patterns looked through the eyepiece and how the area of sky looked with the H-Beta filter installed. I managed to avoid seeing an artifical light of any type for over an hour I think and by that time the reticule on my Rigel Quickfinder seemed glaring even at a low setting, so I switched that off. After all this the Horsehead Nebula was very, very subtle as I describe in my observing report. It's a weird way of spending a few hours isn't it ?. But, my goodness, its satisfying when it eventually comes together