chiltonstar

Worth mentioning (re the cooling issue of Big Maks) that an insulated cover helps enormously (threads here and on "another forum"). Worth doing - mine is ready to go very quickly and the dewing is very much slowed down. On a good night, mine gives beautifully sharp star images at x270 and x350 with clear diffraction rings I've never seen when I've peered up an SCT, or in the short time I had a 150mm newt on loan while its owner was Stateside. Chris

As above, two nights of superb lunar viewing here too with my 180 Mak - two passing dog-walkers enjoyed the view as well last night, although the dogs got bored! Chris

Until Vega and the D-D are quite high in the sky (>15 degrees up) I find the seeing often quite poor in this (E) direction. Once up a bit higher, and the D-D are clearly separated with any of my four scopes and a delight! Persevere! All of us who looked at Saturn last year will be aware of the problems of near-horizon viewing. Chris

Many thanks for this Ken. I've joined the group, downloaded and installed the software and thus far, I am impressed. Something to play with on the (many) cloudy evenings! Chris

Coming back to (astro) spectroscopy after a year or two in the wilderness, I've been trying to get corrected spectra using VSpec. The spectra are objective prism using an high-quality H&W spectrograph prism on an ED80. In terms of sharpness, it appears to work well and I get half band widths of about 0.7 nm at 486.1 nm H Beta (see examples attached, uncorrected). However, as the spectra are prism generated, correction with three wavelengths is necessary to linearise the wavelength scale. All works well until I try and use the response curve profile to correct another spectrum - it always crashes in the same way, with an "unexpected error". Is this an issue because of the non-linear scale (even though they've been linearised or something else ? Anyone an expert?? Should I be switching to RSpec therefore (VSpec is not the easiest software to use after all)? Chris

I use a 9x50 RACI with an RDF mounted on it, ie find the area with the RDF and then use the slomo to center the target with the RACI. To avoid the problem of the two eyepieces being too close together, I have my 127 Mak mounted in rings so that the scope EP can be rotated to the right and the RACI EP to the left slightly. Chris

Interesting! I bought mine from Vixen just as an achro doublet, and made the cell and tube assembly. The lens was pretty good, but eventually fungus invaded the edge of the lens and one of the Al tabs moved so last year I disassembled it, cleaned up the surfaces and re-assembled it. I experimented a bit with the spacers and found that a slightly thicker spacer worked a lot better than the original, and I've since had some very impressive views of 1 arcsec doubles with it, as well as Saturn and Jupiter. I have heard that sometimes the pair of lenses are not properly lined up and positioned in the cell - maybe just a rumour. Chris

It appears on the web in several places with that name. Obviously one of the OP's favourites! Is is a superb double star though - even my grab 'n go 127 Mak shows it in its glory with a little diamond pinpoint secondary; my 180 Mak shows more of the associated stars/companions (see other posts on this site for details, eg by John). Chris

This is my garden - seems accurate'ish. Chris

What a lovely scope! Not as large as I would have expected either, although lifting it onto a tripod plus extension probably requires a fair bit of spinach, or a platform. It will be interesting to see whether the 1.6x gain in light throughput cpd with the 120ED will make resolution of close unequal doubles easier for example? Chris

Quite a challenge this one and one for larger scopes! Fairly easy to locate near the North America Nebula, and perfectly positioned at the moment well above the horizon. The separation is given as about 1 arcsec and the magnitudes 3.9 and 6.8, which I reckoned should be do-able with a 180 Mak. First try, Tuesday with good seeing (4/5), nearby Delta Cyg was easily split and showing the secondary as a diamond pinprick, while Tau Cyg showed no sign of a secondary. The next evening (Wed), I got the faintest hint of something in about the right place, and third try (last night seeing 4.5/5) there it was in moments of good seeing at x270 and x450. Clearly separated from the primary, but messed up a bit by the diffraction pattern causing to hop in and out of view, as the secondary lies close to the first diff ring. I can't sketch very well, but the Aberrator simulation below is a fairly accurate eyepiece view at x450. A good one to try if you are bored with looking for some detail on Mars! Chris

Indeed yes, mine will show the division all the way round when Saturn is high enough and appropriately tipped. They are lovely scopes for the size and weight! I use a 3.7mm orion EP for planets. Chris

Horses and courses, I find. I love the clear views from a frac of planets, doubles etc, but as stated above, they cost a lot more per inch than a Mak and the convenience of a short tube, 180mm Mak is something a frac could not deliver. Fracs are better though when the seeing is poor as the more visible diffraction pattern from the Mak can end up as a bit of a visible jumble, for example around double stars - an issue with any scope with a significant central obstruction. The resolution of my 127 Mak (it's actually 119 mm clear aperture) is visibly better than the resolution of my 102 mm long tube frac, but in terms of brightness on a DSO like M1, they are about the same because of the obstruction and more optical surfaces of the Mak. Nowadays, I get the best of both worlds - I put both my 180 Mak and my little ED80 on a SkyTee2. Chris Chris

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