John

The diameter of the AZ100 body / mounting plate is as the name suggests, 100mm. The ADM clamp fitted and worked fine but did look a little puny against the bulk of the AZ100 mount head. A losmandy / vixen dual fitting plate (by any good manufacturer) would look more to scale. The Rowan ones are rather nice though and do match the finish of the mount perfectly as you would expect.

The spec of the same scope marketed under Orion (USA) branding gives the secondary mirror minor axis as 58mm. Granted that would be bevelled as well so the aluminised surface will be more like 55mm or so. I wonder if the secondary mirror on your example has been changed by a previous owner ? I also wonder if the primary has been moved up the tube at some point - the Synta (the manufacturer) newtonians generally have the focal plane of the scope not far outside the scope tube wall. Interesting stuff all the same - good experience. FWIW my Orion Optics 12 inch F/5.3 has an aluminum tube and a 63mm MA secondary which is the OO stock size for this scope.

The eye relief on the 32mm TV plossl seems to be longer than the rubber eyecup which is why I find that the eyecup extender makes it an excellent eyepiece. I like to have my eye snuggled up to the eyecup so that a) the eyecup does its job and keeps stray light off the eye lens and b) that the edge of the eye cup acts as a quick reference point for the positioning of my head and eye in the dark. I really don't like having to "hover" my eye someway off the eyecup. Without the eyecup extender accessory I was less comfortable using the 32mm TV plossl despite it's excellent build and optical qualities. I don't wear glasses when observing. FWIW I'm finding the 92 degree ES 17mm and 12mm very similar - but there is no eyecup extender option as far as I'm aware.

I've not had any dewing on my 130mm TMB/LZOS triplet while observing. As with Michael, the objective has misted up when the scope is bought cold into the house after observing but that clears quickly and without residue when as the scope warms back up. I've not had any misting between lens elements or on the inside surface of the objective even when the glass is cold and the house warm. The tube on my scope is made of Kruppax which seems to be very good at stopping the objective dewing even when the outside of the tube is dripping wet. I guess if triplets routinely dewed / misted on more than the externally facing optical surface, they would be deemed pretty impractical scopes in UK conditions ?

My earlier 2 posts were made in 2016 when this thread was young. My more recent one (after Alan's re-boot of the thread) was simply agreeing that personal feelings on an eyepiece can change citing the Nagler zoom as a personal example. Your post introduced two different eyepieces by different manufacturers which did not seem relevant to the topic being discussed since Alan updated us on his experience with the 32mm Tele Vue Plossl. Still, no harm done so lets just move on ?

I think Stu makes some valid points. With my 12 inch dob and an excellent H-beta filter the Horsehead Nebula has proved a very challenging target needing the darkest skies, lots of research and practice sessions and even then I have only barely glimpsed it as a slight darkening against the background nebulosity (which is very faint in itself). An O-III filter actually makes it harder to see than with no filter at all. There is a dark rift within M42 (the Orion Nebula) that has been mistaken for the Horsehead Nebula by others in the past ???? This area is known as the "fishes mouth":

Good points Alan. A discussion of other max field 1.25 inch eyepieces can happen in another thread. I'm pleased that you are pleased with your 32mm TV plossl

I'm just back from a society outreach session at our observatory. Dead cold up there so I'm glad to be back inside now. Good session though with initial cloud cover clearing rapidly to give some great views of the Autumn favourites. I never tire of hearing people say "wow !" when they look at an object through a scope for the 1st time even if it is a target which I'm familliar with. Hope you feel better soon Stu.

Nice report - glad it's all working well for you I guess you know this but in case you dont, if you rotate the eyepiece (loosen the set screw holding it to do this) the polarising filter roatates too and that controls the amount of light that comes though. My setup (same as yours) varies between a bit too bright (though not hurting in any way) and a little too dim so finding a position where the image is the "right" brightness is straightforward.

I think "patchy" would best sum up 2019 in terms of astronomy for me. The observing conditions seem to have been more challenging than in previous years but that might just be my memory playing tricks on me ! I seem to have settled now on my scopes, mounts and eyepieces. I've had a play with one or two new things during the year but not with any seriousness in terms of longer term changes I think. I probably need to substantially downsize my collection of gear at some point. Being honest with myself about it, there is quite a lot of stuff that is only getting occasional use (ie: a couple of times in 12 months !) but I'm always plagued by the "you might miss it when its gone" thoughts It is interesting looking back over the past 3 years, especially since I was able to acquire some marvellous scopes and eyepieces during that period. It's been a delight to be able to observe with top end scopes such as the Tak FC-100DL and the TMB/LZOS 130 F/9 triplet and satisfying to experience the purity of their performance but have they actually been game changers in terms of my enjoyment of the hobby ? Not really, in all honesty. Thats a tribute to my trusty Vixen ED102SS, Skywatcher ED120 and Orion Optics 12 inch dob there Anyway, I'm hoping that the coming months will provide more observing time and more outreach opportunities. I really enjoy sharing this hobby with others more perhaps than any other activity

Galaxies and nebulae (with some notable exceptions) can be hard work with a 70mm aperture scope, especially if you have some light pollution to deal with. If you want to rack up some Messier and NGC objects then open clusters and the brighter globular clusters will prove more fruitfull I think. I managed to see loads of open clusters with my old Tasco 60mm refractor

Its more likely that you saw M32 rather than M110. The latter object can be challenging with 100mm of aperture unless the sky is really dark. As Stu says, M33 is faint, extended and hard to see despite what it's integrated magnitude figure (6.7 I believe ?) would have you believe. Again easy to overlook with a 100mm or larger aperture if you don't know just where to look and what to look for. Low power generally is the key to these particular targets.

I use a Rigel Quikfinder on my 12 inch dob instead of a Telrad. It works very well.

If you loosen the two nuts a little you might be able to wriggle the finder around and find a spot where it matches the scope view more exactly. They do seem to have limited adjustment in the fitting itself which is why some movement of the base on the scope itself is required. That might get you by until you get the red dot replacement finder (which is probably a good plan by the way)

Thats looking grand Stu Hope you are feeling better soon and that the skies clear so that you can give the AZ100 some good star time

I found the TV 32mm plossl excellent when the eyecup extender is fitted but rather frustrating without that accessory. It is funny how ones impression of an eyepiece can change though. I owned a couple of 3-6mm nagler zooms in the past but didn't take to them. I've had the 2-4mm version for quite a while now (same ergonomics) and I really like it. Go figure, as our US friends sometimes say

If the finder scope is the type that is held to the scope tube with 2 nuts then you could shim the base of the finder mount to tilt it slightly when it is screwed on to the scope tube. Assuming that your finder looks like the one below, I've indicated where you could shim the finder mount to tilt it:

I use the Delos 17.3 and 14 with the Pentax XW's 10 thru 3.5mm. They play very nicely together

I have the 2-4mm nagler zoom (out of production now) and its an excellent high power / very high power eyepiece. I've owned a couple of the 3-6mm versions in the past as well - just as good !

My travel / outreach set is pretty much that - the zoom plus the barlow plus a 30mm 2 inch wide angle eyepiece.

Which one ? There is the 7.2mm - 21.5mm and the 9mm - 27mm. I have one of the former type (different branding but the same eyepiece) and its pretty nice. The main drawback is that the field of view at 21.5mm is rather narrow - around 38 degrees I reckon. It widens to around 55 degrees at the 7.2mm focal length. This characteristic is quite common with zoom eyepieces. I mostly use mine with a 2.25x barlow to create a variable foacl length high power eyepiece and the optical quality is quite impressive even compared with somewhat more expensive alternatives. Without the barlow the 7.2-21.5 zoom is a good eyepiece for solare observing, either H-alpha or white light.

I've learned to try a wide range of magnifications on DSO's as well as solar system targets. High magnifications are needed to separate the smaller planetary nebulae from stars although NGC 2392 (Eskimo Nebula) is not that small. 250x does show it's central star and can help discern it's layered structure a little more clearly. To see the E & F stars in Theta 1 Orionis (The Trapezium) I've found around 200x is an effective magnification and these additional members of this group don't get easier with higher powers in my experience. Using 400x with an 8 inch scope under the conditions that we usually get in the UK is not going to be useful very often on DSO's or the solar system, I agree. Maybe it was a typo by the magazine ?. They do happen.

If FPL-53 is used it tends to get mentioned in the spec because it's expensive. If it's not specified then it's much more likely that the ED glass is FPL-51, FPL-55, FCD1 or similar.

Personally I cant make much of the pictures so I tend to concentrate on the figures, particularly Peak to Valley, RMS and Strehl. The wavelength of light that these measurements were made under is also significant I believe. Some wavelengths are more significant for imaging and others for visual observation. The other thing is that the tests just relate to a single example of course. You get some variation across a production run. Less probably for a premium product. I doubt there are any poor Vixen 102 fluorites or Tak FS 128's around though ! (Canon Optron made the objectives for both of them BTW)

As the owner of a DL I've been watching the WWW closely for this but I've drawn a blank so far as well. I suspect the difference in visual observing will be miniscule or not discernable at all. From the data published so far on the DZ it seems that the main benefits come in the objectives performance when the approprate Tak focal reducer is used so imagers might be the principle winners. I'm sure someone will have the 2 scopes side by side at some point though.