Background
In December 2022, there was a number of times when I grabbed my grabngo 102mm Maksutov on the AltAZ mount. However, I wanted just a little more impact, so I put my 140mm Maksutov, the OMC140 on it. That was on the edge, it vibrated quite a bit. A nicer image, though. Then I got the bright idea to put the Azimuth arm of the mount upright, so there was much less vibration coming through to the telescope, a huge difference. Focusing on the planets Jupiter and Mars thus became a lot easier. Still not satisfied because of the increased weight and the small field of view ( focal length of the OMC is no less than 2000 mm) I looked forward to another solution for the grabngo thing.
Coming up with a solution
My old Vixen ED
Ah yes, that C.A.
Anyone who knows even a little about it immediately shouts, "Chromatic Aberration!" As if that is all you think about. Some then. The chromatic error of an achromatic refractor has never bothered me, secretly I even find it pleasant. Even enjoyed the color in the 150mm
Bright stars of magnitude 1 or 2 show it as a blue blur, at magnitude 3 you already have to look harder for it. On deepsky objects and large star fields you don't see it at low magnification. At high either. Not so. In that case it is not inferior to my 102mmf/9 ED Vixen.
On the Moon you see at magnifications from 36X a blue edge, but on the terminator not or hardly. Also not at higher magnifications. Details on the terminator would "drown" in a blue haze. Well, not really much. In Plato, I saw the familiar proprietary distortions on the crater floor and one small crater. My Vixen ED shows two. Granted, the shadows in the craters in Clavius were deep deep dark blue and not black. Nor does it really reach the maximum of 2XD in magnification. Above 167X, though, it was over with more lunar detail.
On planets, it is not a high flyer. I did see a loose dark structure on Mars, but the red of the planet "bled" a bit into space. Typical of doublets. On Jupiter two bands of clouds with some nodes in them, the whole thing surrounded by a slightly colorful fog ring. Not convincing as a planet telescope. An understatement.
Since the telescope can also be used during the day, as evidenced by the Amici prism supplied and not used (by me), I subjected that to a little investigation as well. In backlight and as the only subject black branches or crows, the blue is obvious. In normally lit subjects, it is not so noticeable. The manufacturer provided the lens cover with an additional 52 mm lockable hole. Especially for daytime use. That way it becomes an
Star testing
Because all Skywatcher telescopes that had come to me so far suffered to a greater or lesser extent from
Supplied accessories
Included were a 25mm and a 10mm eyepiece, a 2X barlow, a reddot finder and an Amici prism. I did not include the eyepieces or the prism in my tests. I just used my own higher quality stuff, including a Baader prism, a 24mm Panoptic, the Leica ASPH, a Morpheus eyepiece and a Baader Zeiss barlow. And as a finder my 50mm
The Focuser.
Focuser is a standard one from Skywatcher. Just one with a rack and pinion. Heavily maligned, but it is not too bad for me. Especially for my visual use. The German firm Teleskop-Specialisten adjusted it fine before shipping. I have no complaints about it. An
Extension tube for Zenit
To allow the telescope to also see into the zenith without the mount getting in the way of the back of the telescope, I had to mount an additional extension after the prism into the rotating helical. That way the rear end "slides" up a bit forward, deeper into the tube. So it is still possible to observe in the zenith.
Finder and balance
It comes with a red dot finder. I can use that, but I prefer a
First light
On January 30, it was clear. In the afternoon I had already had the telescope outside for a while to view the Moon in daylight. In the evening, heavy clouds passed by, but occasionally it stayed open for a longer period of time. Seeïng was not top, neither was transparency and then there was the Moon! However, you can't have everything.
Once cooled down ( about 15 minutes) I aimed it at Aldebaran. A beautiful red "pit" welcomed me, complete with a small blue cloak. A quick star test. The results are above. Double star Castor was obviously a breeze, Rigel was a little trickier, while Alnitak's double was at the limit of seeing possibilities. Trying any closer made no sense.
On to the Orion Nebula, which in the 14 mm Morpheus eyepiece could be seen neatly between NGC1980 and NGC1981 in one field of view. Breathtakingly clean. Now that's what you bought a telescope for! The Trapezium was neatly depicted as four separate "needle prick" stars, something you can sometimes miss in large binoculars due to image errors.
Picture from Stellarium.
And this was my own sketching, two years ago.
I barely recognized M35 at 20X, only at higher magnifications did I see how beautiful the open cluster actually is. Also briefly looked up NGC2392, the Eskimo Nebula. At first a very small ball of fog in the midst of a rich star field. A little sneeze. At higher magnifications, the central star popped up with averted vision.
The Moon, already discussed earlier, at higher magnification with a blue edge, however, not on the terminator. Plato with one crater pit in it as well as the uneven shades of gray on the crater floor. Clavius' small craters, however, did show a deep dark blue shadow. The level of detail in debris around craters is just below that of my Vixen ED. Magnifying higher than 167X made little sense.
The same was true for Mars and Jupiter. Mars did show at least one dark
And finally, the way it held up on the Alt Az mount. And that was neat. Because of its low weight and upright Azimuth arm, vibrations are minimal. A tap against the tripod leg is not even seen. Focusing does, but in such a way that you don't have to let go to see the result of your effort; it extinguishes almost immediately. The helical spacer allows very precise focusing.
A nice grabngo!
I hope you enjoyed the read.