Thanks Matt, I'll have to check them out. In the meantime....
Take one back side lens cap for the T-ring, add one GSO 2" to 1.25 inch adapter, duct take them together. I ran out of black duct tape so had to use grey. Bayonet fitting to T-ring. Slide Expensive TV eyepiece into assembly and hope that it doesn't fail. When has duct tape ever failed? Don't answer that. All ready to observe! Cat accessory not included.
Well I just did some preliminary testing on trees about 150m away. Comparing views through the field flattener to straight through... the Orion photo FF actually seems to work. The leaves were in focus from edge to edge with the FF but definitely had field curvature without it. Of course I will have to wait until tonight to do some real star tests. But this problem seems solvable, which is what I wanted to know.
Barry, where are you going to use to view from? Suburban or dark site?
I'm currently observing mostly from my backyard in Bortle 6 suburban skies (north Adelaide), but will be moving in October to a new place in Tasmania, south of Hobart, which is a lovely dark Bortle 2 location. Can't wait!
Overall, I've found the feedback/discussion on this thread extremely useful -- thanks. I'm hardly a newbie, but I've never looked seriously before at that 'transition zone' between narrow-field large aperture Newts/SCTs and the ultra-wide-field but very low mag binoculars. So I've really been working to fill my gap in knowledge regarding the rich-field refractors.
The point about a sweet spot in terms of the aperture vs FOV trade-off in picking up the best that rich-field viewing has to offer was very important and something I'd not really computed in my mind until now, as was the issues of field curvature (I'd mostly been thinking about CA, but for what I want to use the scope for [visual, large DSOs], I'm pretty assured that this will be manageble.
This feedback has helped a lot. I've decided to go with the SW120 f/5. It's hardly a large expense, and if I get the taste for wide-field refractor work, I will look seriously at upgrading to a quality APO in the future. For now, a simple, low-cost achro with a decent aperture will meet my 'in between' needs nicely, I think. My SCT will remain my workhorse, but this will be well used too.
I'll be sure to report back on this thread with some real-world feedback once I've got it up and running and tested for a while. (I'd like to take it up to some dark skies within the next month or so, for a proper stretch of its legs!).
Kevin, out of interest, where did you get the Orion FF, and was sort of $$? (I may start dabbling -- strictly for personal edification at first! -- in some astrophotography using the SW120, hence the general interest in this...)
Just tried the field flattener visual and it works. Stars were great right across. Straight through not good on the neck though. I wonder why these aren't more common? Can't they be built into a diagonal or something?
I recently went through this exercise and decided to buy a 102mm Bresser Messier f5.9, 600mm fl achromatic. This scope is not available in Australia but is available directly from Bresser in europe.
Hi Glen,
That is not correct Glen, Bresser are available in Australia from Extravision in Queensland, as they are the Australian agents for Bresser.
What I said was that model Bresser Messier AR102S f5.9 600mm fl OTA is not sold, or stocked in Australia. I know there are Bresser agents here but none of them carry this scope. It is also unavailable in the US. Only Bresser in europe offers this model. I don't know why that is so. The longer AR102 f9 1000mm fl scope is what is sold here.
If you don't believe me check the Andrews website or ring the other stockist.. I only mentioned that scope to try and give the guy an option. I have given plenty of my business to both Andrews and Extravision. I'll give up helping people out and leave it to the experts.
Hi Glen
That scope is available in USA from Telescopes.net, which is part of Woodland Hills Camera and Telescopes.
It is f4.5 according to their website, and seems to be recommended for low power wide field work, which is what the OP wants.
Cheers
What I said was that model Bresser Messier AR102S f5.9 600mm fl OTA is not sold, or stocked in Australia. I know there are Bresser agents here but none of them carry this scope. It is also unavailable in the US. Only Bresser in europe offers this model. I don't know why that is so. The longer AR102 f9 1000mm fl scope is what is sold here.
If you don't believe me check the Andrews website or ring the other stockist.. I only mentioned that scope to try and give the guy an option. I have given plenty of my business to both Andrews and Extravision. I'll give up helping people out and leave it to the experts.
Hi Glen,
Sorry Glen, from reading the website at Extravision website it states:
" The OTA has a free aperture of 102mm with a focal length of 1000mm and therefore a focal ratio of F9.8"
"The Bresser Messier AR-102 on EXOS-2 offers the ambitious amateur astronomers a good look with a very stable universal mount."
It appears that it is the same model, just with a mount. I would hope that the OTA is also available, but that I simply don't know. However, having dealt with Extravision for years, I have always found them accommodating.
Well, I got a V-style dovetail mounting bracket from Bintel, and with that was able to successfully mount my SW120 onto my 8SE GOTO alt-az tripod. See attached picture.
It works very well indeed, and with the dovetail clamp, it takes all of 30 seconds to switch around the OTAs! (SCT or refractor). The only disadvantage is that because of the length of the focusser + diagonal, the SW120 scope will hit the mount after about 75 degrees altitude (c.f. ~85% for my SCT; I set my slew limits to avoid that). So zenith viewing is out, but I can live with that...
The AZ3 mount that came with my SW120 has not gone to waste -- it provides a MUCH more stable mounting for my 15x70 binoculars, with fine controls to boot.
Tomorrow night I'm taking the new gear up to Stockport Observatory to give it a first 'dark site' run in. Can't wait.
Last edited by Amaranthus; 28-02-2014 at 05:10 PM.
Looks great....they are nice looking scopes, at least. I'll be interested to hear your review, too, Barry. I'm still umming and arrhing over the 102 vs 120 at this stage. It's really going to be a financial decision in the end, I think, even tho neither of them are really expensive in the big scheme of things.
Looks good Barry! Shame about the viewing angles.
Both Baader and Blue Fireball Technologies sell a female to female T thread adaptor that would fit the Orion FF, so an eyepiece adaptor, also Blue Fireball, with T threads on one end and compression spring on the other would mean eyepieces/diagonals will fit without duct tape
Agena Astro in the US have all the bits needed. I'm going to try an Orion FF on my f7 frac soon.
Like to know how the 120 is going Barry.
Matt
Okay, so an update on how the SW120 f/5 has performed.
Eyepieces I used for testing were:
TV Panoptic 24 mm (magnification = 25x, TFOV = 2°35')
TV Nagler T5 16 mm (38x, 2°7')
TV Nagler T6 9 mm (67x, 1°11')
TV Nagler T6 11 mm with 2.5 x TV PowerMate (136x, 34')
I used a TV Everbright diagonal, plus UHC-LPR, OIII, Lunar, and Wratten filters.
First light was under bright Adelaide suburban skies, mounted on the AZ3 that came with the instrument. The mount was okay (the altitude movement is rather stiff -- it is controlled by a friction bolt), and the fine adjustment controls were useful. The finder is a red-dot sight, and was functional.
Bright objects (Sirius, Jupiter) showed obvious bluish CA, but it was quite tolerable and essentially invisible on any object below about 1st magnitude.
However, what was striking was the 'washed out' look I was getting under the wider views -- the sky brightness (a Bortle 6 site) dominated the view to the extent that any significant 'rich field' benefit was lost. With the LPR and OIII filters in, nebular DSOs were significantly improved, and indeed the LPR helped with the stellar DSOs too by darkening the background sufficiently without losing too much light - though it would be a case of diminishing benefit for the fainter (mag 9 and below surface brightness).
My overall impression was that it was 'okay' for wide-field viewing from my backyard, and I'll continue to take it out maybe once a week, but not great.
Then on Saturday I had a chance to take it to Stockport Observatory site in the north of Adelaide (in Bortle 2 skies). Well, my impression turned to It was then mounted on my Celestron 8SE single-fork-arm GOTO mount. Simply superb -- what a difference. Rich fields in the Pan 24 and Nagler 16 were stunning, and when I did the Nagler 9mm x OIII combo, I got my best EVER look at the Rosette Nebula - the gases just hung over it beautifully like a grey shroud.
I ended up getting through about 25 DSOs over about 4 hours of viewing (selected for their wide FOV characteristics, ranging from M45, to Eta Carina, Tarantuna, 47 Tuc, Southern Pleiades, etc.). For these objects, there was essentially no hint of CA (maybe a touch on the M45 stars, but hey, it just made the cluster look cool ) and I really didn't notice any significant field curvature -- certainly nothing that bothered me visually.
The galactic fields around Centaurus, Carina, Vela etc. were magnificent, just gradually wandering over them with the Pan 24.
At the end of my view, for a giggle, I chucked in the Nagler 11 mm with a 2.5 PowerMate and a Neutral Density filter, and looked at Jupiter. Well, it looked pretty darned good -- very little sense of CA with the filter in, and the great red spot and major cloud banks were clear. I was surprised -- I certainly didn't buy this scope for planetary observation, but it did remarkably well.
In short, I was in love with the instrument at the dark site.
So, my conclusion is that it will be a regular traveller with me to Stockport, and when I myself move permanently to a Bortle 2 site in Tassie later this year, well, it's going to get a LOT of use. Overall, very happy.
Thanks Barry, a nice wrap up of the 120. The use of high quality eyepieces does make a difference in these scopes, specially the Pano 24.
I have seen in my 70mm f7 the same thing, FC with cheapish eyepieces and nearly zero with good ones, in my case the ES 24mm 68º is pinpoint to the edge where as the 20mm SWA 70º shows quite a bit of FC. There goes the Orion field flattener idea out the window....
Matt
Bayonet fitting to T-ring. Slide Expensive TV eyepiece into assembly and hope that it doesn't fail. When has duct tape ever failed? Don't answer that. 
All ready to observe! Cat accessory not included. 
It was then mounted on my Celestron 8SE single-fork-arm GOTO mount. Simply superb -- what a difference. Rich fields in the Pan 24 and Nagler 16 were stunning, and when I did the Nagler 9mm x OIII combo, I got my best EVER look at the Rosette Nebula - the gases just hung over it beautifully like a grey shroud. 
