chiltonstar

Welcome - don't worry about your English as it's a lot better than my Italian, and I worked there for 8 years! Chris

I also missed this thread........ Home made OTA using a 102mm f13 Vixen achromat, circa 1980 vintage, on a Vixen mount. Still gives stunning views after 30 years use, and will be out & about for Mars in July! Chris

I use a SkyTee2 with my 102mm f13 scope. It supports it well, but an issue is that you need to buy long cables for the alt and az axes - this is not a problem with my maks as they are short tube. Chris

Very surprising, and excellent! I'll also have a try with my ASI224 on some brighter DSOs. Chris

Well done John! A nice report and a nice night - I gave up here after trying for an hour or so; the Flame Nebula was only just visible, and the HH not at all. It is a target surprisingly dependent on transparency, it seems. Chris

I am not sure I would completely agree with this statement - look at some of the refractor posts where 50x per inch is easily achievable, and very desirable for certain planetary targets! Chris

With a 180 Mak, up to x250 for Saturn, Uranus and Neptune, x200 about optimum for Jupiter, and up to x540 for doubles (above x400 mainly empty magnification, but it does allow the disk diameter and separation to be measured). Chris

Should be easy with the C9.25 if properly collimated, say at 300 times mag. Chris

It would be interesting to see how small a scope can split Lambda Cygni at the moment: mags are 4.73 and 6.26. sep is 0.9 arcsec, PA 359 degrees. Quite a fast mover - 390 year orbit. With my 180 Mak it is a beautiful pair with the secondary as a very bright pinpoint alongside the primary (a very close double itself), both a blueish white colour. My 127 Mak (true aperture 119mm) splits it on a good night, but with some difficulty and certainly not as cleanly as the 180 Mak. Anyone split it with smaller refractors?? Chris

These little scopes deliver a lot for the price - mine has always amazed me in terms of high power views, and even of faint fuzzies! "They" say that five inches is a good aperture for much of the time in the UK because of atmospheric conditions, and I've certainly always found that. It will be interesting to see how you get on with the mount and scope with time - vibration may perhaps be an issue? Chris

I have a copy of a classic Messier objects book (Mallas and Kremer), which gives an idea of what you can see deep sky with a small refractor (100mm achro in the case of the authors, your 120 ED should go considerably lower) and Sue French gives another view in her excellent book. But, as indicated above, you need a dark site and an excellent evening! Chris

In CDSA, Talitha is shown as a triple, with a pair separated by 0.7 arcsec, and the primary 2.4 arcsec away. I see the close pair as just resolved when the seeing is excellent +. Where did your separation figure come from Nick? Chris

...although some of these may have confused the nearby star SAO 305 with Polaris's partner - it's only 1/2 degree or so from Polaris. I have even seen the same thing on this forum... Chris

It's quite a wide double (18 arcsec) so using the normal rule, any magnification above x10 or so would theoretically be sufficient, but obviously the real issue here is the faintness of the secondary. For me, if I can't see it because of the conditions, then the magnification I'm using is probably irrelevant?? Certainly at x60 with my 180 Mak (the lowest practical mag for me with this scope), it's easily visible under good conditions. Chris

I think tube rings would be a good idea in the sense that things would feel 100% secure, and rotation would be useful to get the finder away from the head a bit particularly when I use the scope on my EQ mount, but would add more weight. Fouling? No problems - the 2" diagonal supplied clears the focuser by about 10mm. Balancing is fine on the end position of the SkyTee; if the tube is approximately balanced (which seems to work ok with my EPs and finders given the long dovetail on the Mak), then you can nudge to position like a dob almost and it holds position, thanks maybe to the SW viscous grease. Chris

The RDF to arrive roughly where I want to go, and the RACI to locate exactly. I sometimes use the EDS80 instead of the RACI, but of course the image is not correct orientation, which I struggle with. The RDF is a metal gunsight type - it stays aligned very well compared with the SW variety. Chris

As you can see, I'm a Nikon-man! Chris

To wake the thread up again after a bit of Summer holiday........... My current doubles set-up. 180 Mak with an ED80 on a SkyTee2 mount:- Chris

It might be a best seller........can I pre-order a copy? Chris

I'm impressed you can split Lambda Cyg with 130mm John at 0.92 arcsec (?). With my 127 Mak, it takes a blue filter to split the pair (smaller Airy disk) although with my 180mm Mak, it is relatively easy to get the "dark line". Chris

Electric blue-green with the ED80, faded lilac with Mak 180. Chris

You're right Stu - quite blue. My little ED80 can do it, so your FC100 should manage! I don't think it is a resolution/aperture issue, just getting the seeing good enough for a horizon-grazing star to see the secondary. Chris

Wonderful stuff John. Obviously quite a scope! Delta Cygni is quite a challenge, isn't it? I managed a split two nights ago with seeing 4/5, but 5/5 would have been better. Antares gets easier the more often you split it, I think; the colour contrast is really impressive, even in a small scope but I wonder whether the companion is really blue or if it's just the colour contrast with the primary. Chris

Very nice image John! It's a lovely pair to see visually, even though it's very difficult from these northern skies because it barely rises above the horizon. Chris

I've just had a try with my 180 Mak. At x225, it's visible as two disks very close together, but the seeing here needs to be a bit better for this one I think (at the mo, it's about 2 to 3/5). Good luck! Chris