Hioptic 6" Maksutov Cassegrain NMC1900x152 Telescope Review
HiOptic 152 > Optical TubeO.T.A. (OPTICAL TUBE ASSEMBLY)
GOOD FIRST IMPRESSIONS
First impressions on unpacking the 6" Maksutov OTA is that it has been
built well owing to how big and heavy
it is. Everything is solid metal, even the corrector dust cap!
Without plastic parts like the Meade ETX-125 and Konus Motormax
130 have it feels very solid. The dust cap is felt lined and slides off
fairly easily so readers
are
warned to watch their toes while transporting the OTA!With accessories mounted the OTA weighs in at 6.5kg/14.4lbs. The tube is 178mm/7" wide and 432mm/17" long.
The ring around the corrector lets everyone at the star party know what you've got. Maksutov-Cassegrain design with a focal length of 1900mm, apature of 152mm making it a f-ratio of 12.5. The manufacturers specification suggests a limiting magnitude of 14.8, angular resolution of 0.75 arc seconds and a maximum useful magnification of 300x.
Looking into the front of the scope it was a bit shocked to find almost no evidence of corrector coatings like many of the Meade telescopes have. There is a slight hint of blue tint to the corrector, and in many of the supplied accessories that came with it, but it's hard to notice on such a large piece of glass. I did later get to take the corrector off and I can now confirm from the inside it has an obvious red-brown colour similar to EMC or UHC. I've heard many horror stories of users damaging their external corrector coatings so to have them on the inside seems to be a bonus for cleaning optics and for the clumsy!
GRAFFITI
While inspecting the OTA a line was found drawn in with permanent marker! This is evidence that someone has taken the front corrector lens off the scope after it was manufactured. Annoying that whoever did this didn't use a more subtle method so not to ruin the tube aesthetics. I expect the corrector was taken off to fit the dovetail.
DOVETAIL MONKEY AT WORK
The OTA attaches to the tripod via a dovetail and instead of using £10/$20 tube rings, whoever put this together decided to save a few pounds by screwing it directly to the tube. Looking into the telescope it was a bit worrying to see the mirror riding almost up to the screws. In practice though I've not had any problems reaching focus but it could be problem if you were unlucky enough to get one with the screws mounted just 1cm further back.
There are no baffles in the OTA but the inside is coated with a none-reflective black paint. On close inspection there were some scratches in this paint probably due to the dovetail fitter!
DEBRIS ON THE PRIMARY
Looking at the large primary mirror on the back it gives the impression that whoever made the less than professional dovetail install also left debris from drilling into the OTA. There were no specifications given on the quality of the mirrors and glass but I have seen retailers describe this scope as BK7 and 1/5 wave. I've since had the corrector off and cleaned away the flakes of black paint. The corrector was pleasingly easy to remove unlike some scopes I've owned in the past.
A NICE REAR!
On the back of the OTA there is a 2 inch threaded back. A 1.25" step down ring with 90 degree diagonal are also provided. The diagonal as with many parts on this scope was dirty and required cleaning before use.The focusing knob on the back of the OTA is large was smooth to use providing a lot of focus travel and no noticeable image shift. The knob loosens before stiffening up towards the end of the focusing range giving plenty of warning that there is no more travel left.
Three rubber covers on the back can be removed to reveal six collimation Allen screws. Collimation on Maksutov's is legendary for staying in place so readers are not advised to mess with them until they have ruled all other issues such as bad seeing. The collimation on this scope was very bad when it arrived but I managed to sort it out. I tried various methods but by far the easiest and most accurate was by focusing on a point of light on a TV mast in the distance.