Finally, after recovering from a good hit with pneumonia, I hauled my Orion MN190 Mak Newt astrograph out for a round of visual how do you do's.
First up, as anyone who owns one of these, or the Skywatcher equivalent (slightly different - smaller secondary, pull out visual adapter) knows, they are HEAVY! That meniscus up front is a CHUNKY bit of finely figured glass. Quite nose heavy, and, coupled with a decent thickness primary AND a steel tube, it weighs in at 13kg (without EP or finder). For a 7.5" scope, it is heavier by far than similar aperture Newts, RC's or Schmidt Cassegrains. So, you need a decent capacity mount to push it around - I ended up with a Celestron CGEM - rated to 18kg - and am very happy with my choice. An EQ6 would handle it just as nicely.
Balancing the OTA required 3 counterweights - one standard Celestron CW (same as the EQ8), and 2 x SW EQ6 5kg counterweights (with the plastic shim removed, as the CW shaft is thicker, like the HEQ5). Balancing in dec required the tube to be shifted well rearward of the geometric centre thanks to the meniscus. Balancing in RA was simplistic enough if you have ever balanced a Newt before, compensating for the assymetric weighting due to the offset focuser (which will hang vertically for imaging anyway). Having a steel tube makes adding magnets as offset weights easy.
So, how did it go visually? Well, I didn't allow it to cool to ambient before I took my first look, but I must say that the initial view mere minutes after setting up, showed beautiful results. My meticulous collimation with a laser, followed by a Cheshire and lastly an Astrosystems autocollimator paid dividends - the stars are pinpoint, and the field is flat to the very edges of the field - absolutely no coma detected at all. As has been implied before, it really is a 7" APO refractor at 1/10th the cost. The contrast is very nice indeed as well, with deliciously inky background studded with pinprick stars, showing all the right colours (with no perceptible colour fringe whatsoever).
After allowing a 45 minute cool down, I took another look, and it was then that the penny really dropped. All I can say is WOW! Breath-taking, delightful WOW.
I certainly cannot wait to do some imaging with this scope!
Pros:
1. flat field, without needing a coma corrector
2. no diffraction spikes
(personal preference I know)
3. high contrast, no fringing
4. decent 7.5" aperture, at 1/10th the cost of a similar size and speed APO refractor
5. superb visually for an astrograph. Anticipated imaging results should concur
6. fan can be added to primary casing (but otherwise covered with a screw down plate)
Cons:
1. Heavy OTA
2. Meniscus prone to dewing and dust/dirt/fingerprints (a dew shield is a MUST, and heating probably
3. stock focuser is really average. Perhaps it is just my example that had rust on the centre of the pinion, but I am not overly happy with the focuser and have ordered the full Moonlite kit, with stepper motor etc.
It's definitely won the spot of imaging scope in my stable, but, whilst it is visually superb, it cannot compete with my Vixen FL102S, that really is truly sumptuous visually.
As to the Celestron CGEM, I must say I prefer it over the NEQ6 in MANY ways, not just the NexStar software which I believe to be far superior (though more complicated) than the Synscan. The build quality is better than the NEQ6, and it is appreciably beefier. The motor noises are louder, but on the same token, are no where near as high pitched and whiny as the NEQ6 motors. When tracking, it is more of a murmur than the shrilling high pitched song the NEQ6 sung (all examples I owned). There is far less slop in the dec head, and the dovetail head is longer than the NEQ6 (but the CGEM only accepts Losmandy D rails). Altitude adjustment is really nice and positive, with a large head screw jack compared to the fiddly elevation screws the NEQ6 has. It also sports a surprisingly accurate elevation scale with a fine pointer. The clutches seem much easier to lock off than the NEQ6, requiring very little force, They also unlock without "break tension" required. The RA rotation is very smooth, very low friction (no drag or bind anywhere). The Dec motion seems stiffer, but that is probably a good thing.
The CGEM is heavier than the NEQ6 (both without counterweights), but I don't mind that. I find it easier to man-handle than the NEQ6, as it has a few more places where you can grab it without fear of breaking something. You'd think the NEQ6 and the CGEM would be more similar, being made in the same factory (one presumes), but they are worlds apart.
It is also interesting to note a few "off the shelf" CGEM parts Synta recycled into the EQ8 - off the top of my head: power switch, power connector (thread on), counterweight design (maybe the EQ8 hole diameter is larger - the CGEM is 20mm).
All in all, I really like my new toys. No doubt, some of you saw and possibly played with my MN190 at Astrofest this year, as I bought it from Phil after AF. It needs a new focuser, but apart from that, I am thoroughly rapt.
excellent Lewis , if she is anything as good as my M210 you are on to a winner , I have always admired these Mak Newts .
Oh well its just that you cant get nothing for nothing , its a trade off sometimes , my M210 is ready in 1/2 an hour with its lovely open tube , but it has Lewis's pet hate ,,,,
, they don't worry me at all .
