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MesuMount 200 Review
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MesuMount 200 Review
I must admit this review is way overdue. I’ve been planning to write it ever since I received the Mount on Christmas Day over three years ago from its designer and fabricator Lucas Mesu.
There are few reasons I decided to go with this particular Mount. I was looking to get a good platform for a 14-16” instrument I planned to use in my country house observatory for astroimaging. It had to track accurately at longer Focal Lengths (2-3m range). My other telescope is an 11” SCT in Hyperstar configuration, its Focal Length 560mm. I was OK using Celestron’s fork mount on a wedge. In new setup I knew I needed something much more substantial. I planned to use OAG, not the guidescope, as flexures would undoubtedly play a major negative role here.
In doing my initial research I saw a few references to this innovative design idea, uncommon in astronomical mounts, called friction drive. It uses pin and disk instead of gears and worms. In utilizing this design there’s no play and no need for “loading” the gears by weighing east end of the telescope tube. There’s also no backlash, since there’s no meshing of the gears. Periodic error is also supposed to be negligible.
It all sounded great in theory but how would it be in real life. Also, I was quite leery about equipment being made far from home and by a small operation. What bought me in was this article in ATT (No.6 2012) by Oliver Penrice. I finally bit the bullet and ordered mine. There were few options to consider, e.g. counterweights, semi-pier, tripod and (at that time) the control unit. Currently the only option for that is highly acclaimed SiTech. I went with bare-bones Unit and SiTech controller.
It took 2 months for Mesu to build everything, delivery from Holland was a speedy one-week affair. It came in a very sturdy wooden box, undamaged inside and out.
Picture 1. Delivery of MesuMount200
I put it all together an a few minutes on a Meade heavy-duty field tripod first to test with my trusty 80mm WO refractor. No counterweights were needed, just a counterweight bar. The Mount barely noticed that small refractor. Yet, everything worked perfectly fine. I even tried to do couple of unguided test exposures.
Picture 2. WO80 set atop of the Mesu.
Few notes on the usage of the Mount. It is designed mostly as an astrophotography platform. There are of course times when you’d want to use it visually without computer. It works perfectly fine as such. There’s a simple pushbutton hand pad that comes with SiTech and you can be star-hopping in no time. Of course real treat is to use it with a planetarium program and full computer control to take advantage of all the features this Mount can offer.
In order to set it correctly after the initial Polar Alignment, SiTech needs a few “CalStars”. If you trying to use it visually or just for initial testing, 3-4 stars is enough. In my Observatory setup I use upwards of 36 CalStars as equally distributed across the sky as possible. After I have my sky model loaded, I do “OffsetInit” to tie actual sky to the model stored. From this point on I am set to go.
As far as I understand any planetarium program that uses ASCOM protocols will work with the Mount. I tried two free ones - Stellarium and Cartes Du Ciel. Both worked fine but I prefer the latter as it is more comprehensive and goes pretty deep. There’s also a built-in application “SkyView”. I‘m sure that one works too but for now I’m happy with CDC as it seems to do what I need.
Now, after that initial testing I was ready for real use under semi-rural skies in the country. I ended up using a 10” SS tube filled with sand as a pier, attaching the Mount directly to the top flange. No flexing here at all. To get the Mount Polar Aligned there are two bolts each axis with a set of knurled nuts. For initial crude azimuth setting there are holes drilled on a half-disk in which you pick one closest to your latitude. I used PhD for fine-tuning my Polar Alignment. Set it once, tweaked it on one more occasion and left it alone.
The scope I ended up buying is Celestron’s excellent 14” EdgeHD. The overall weight of the tube with all the accessories, cameras, Moonlite focuser, etc. I estimate to be around 35KG. The rated capacity of the MesuMount 200 is 100KG. I am OK there.
Picture 3. EdgeHD 14 mounted.
Friction drive is somewhat sensitive to balancing. If the disbalance exceeds 1 kg-m, it will slip. It’ll still know where it is pointed but the tracking will stop. I take care in re-balancing it every time my setup changes. Once it’s balanced, it’ll work fine without issues. Since we are on the balancing, the weights need to have 40mm central bore. As far as I know the only available option in the US is from 10 micron. I chose to order mine from a local machinist. The ones that are on the tube for the DEC balance I sourced myself and attached to the top bar on the tube.
SiTech controller (Servo Controller II) is a made by an American Company Sidereal Technology. It is a well-established firm with a great customer support and a loyal following among diyselvers and telescope retrofitters. The one that came with my mount was pre-configured for it. I also got an e-mail with initial settings that were plugged into their controlling software program - SiTech.exe. The firmware is being updated regularly and author’s feedback on the Yahoo tech group is timely.
I think I covered most of the positive aspects of the Mount. As for the negatives, to be honest I really don’t see that many. One thing many people mention is the aesthetics. I follow mantra of beauty following the design. In that respect it looks great to me.
Another thing would be to see SiTech Unit covered where all the electrical connections are made. Also, more important to me would be through the shaft cabling. That is implemented in the bigger model, not in the MesuMount200.
I want to emphasize that I am using the 14” SCT Scope with pretty long F/7.7 at 2738mm focal length (with 0.7x focal reducer). Yet, my RMS tracking error typically is 0.2-0.3 arc-sec. I routinely use 5 sec. exposure time and sometimes longer (up to 10 sec.) with good tracking results. This Mount seems to take long tracking exposures easily. It helps especially at nights with below average seeing, as I’m not chasing it.
Picture 4. PhD graph.
As for the results, I want to share just one, M82. It is uncropped and was done within one night, using Atik460EXM with filter wheel through Luminosity, RGB and H-Alpha filters.
M82, Total exposure about 5 hours.
All these years the MesuMount200 served me very well. I’m yet to see any problem requiring a service. As a matter of fact I am yet to see a single frame that was lost due to the Mount. I think it nicely fits the niche of a midsize observatory or even a large field mount. It is priced very competitively. If you get one I’m sure you won’t regret making that decision.
- schmeah, jrbarnett, Alterf and 16 others like this