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Vixen Mini Porta Mount
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Vacation time and I’m off to the sunny South for two weeks! But, given my new found addiction to all things astro, I can’t possibly go without a scope, can I? There are many good options for a travel scope, but since I already have an Orion ShortTube 80 and an EON 72mm ED and they are both well sized for travel, all I really need is a good lightweight travel mount!
There appear to be few options in an alt/az for something that folds up fairly small, weighs little, and is reasonably sturdy. I decide on the Vixen Mini Porta Mount. Vixen seems to be a respected name in the industry and it just looks like a scaled down version of the well-reviewed Porta Mount. At $199 it feels a bit steep, but I figure you get what you pay, right? So I send my two C-notes out the door and await the arrival.
What I received surprised and disappointed me. But more on that later. Let’s start with the basics. I set up the mount with my Orion ST80 for a quick photo shoot.
Weight: 6 pounds including tripod
10 pounds according to web site
7 pounds according to included manual
Tripod height: 28” to 51”
Slow motion controls: Worm drive, with 120 tooth driven gear
OTA attachment: Vixen style dovetail seat with safety screw
The altitude and azimuth axes are shown in the following photos. Note the allen screw heads in the body near where the slow motion handles attach. These are handy access to the clutch adjustment for each axis. A nice touch!
The Vixen dovetail seat on the altitude axis is attached with four bolts, and the overall mount arm is attached to the base with two underneath a rubber panel. When removed, these expose additional bolt holes so that these parts can be reattached rotated at various angles relative to the slow motion handles. This is a nice feature which allows you to avoid interference between the handles and your scope in almost any situation.
Note in the previous photo that the rubber panel over the azimuth bolt also covers a built in tool kit comprised of two allen wrenches (for clutch adjustment and axis removal) which are held in place with two round magnets that can be seen in the following photo.
This would be a handy setup except for a couple of problems. First the magnets came out with the allen wrenches the first time I removed them. I had to epoxy them back in to get them to stay in the base. Second, the rubber cover is rather difficult to get back on. It takes some doing to work the rubber barbs back into the holes in the housing. This is not a big deal since you should not have to use them often, but it is an annoyance especially if you need to adjust the clutches in the dark. In this situation I ended up putting the cover in my pocket to be reattached later when back in a well lit location.
Spreader and Eyepiece Tray
The tripod has a spreader in the middle and it comes with an eyepiece tray which screws onto the spreader. While the rest of the tripod and mount seem well made, these pieces were most definitely not. The spreader is made of plastic and just feels flimsy. These photos show the top and bottom of the spreader.
The eyepiece tray is even worse. When I installed it, it was noticeably off kilter, and it wouldn’t screw in all the way. After careful inspection, it was obvious that the bolt had been molded into the tray at an angle, and the plastic molding covered part of the threads on one side which would not allow it to screw in completely (center photo below). To add insult to injury, three of the six holes in the tray are for 0.965” eyepieces! The remaining three holes were too close to the edge for most of my eyepieces to fit without hitting the tray’s rim. One has to wonder what market the target market is for this mount with 0.965” holes.
A final nail in the coffin of this tray is how it mates with the spreader. A well designed tray could have added strength to the spreader by pushing against its struts when seated. But, notice that central nub on top of the spreader in the left photo above? Even if the bolt was straight, free from excess plastic, and could seat all the way, the tray would be supported only by this small piece of plastic and would not contact the spreader in any other location. This leaves the spreader weak, and makes the thin plastic tray feel very wobbly. The whole setup left me feeling like I was going to break something when setting an eyepiece on it.
For all intents and purposes, this tray is useless. I’ll be replacing it with a piece of plywood drilled to allow the central nub to fit through, with holes large enough for normal 1.25” eyepieces, and secured with a washer and thumbscrew above the central nub.
Slow Motion Handles
The supplied slow motion handles were the next problem with the mount. They were push-on and held in place with a piece of spring metal inside the end, which pressed against a flat on the shaft (left photo below). Unfortunately, the lack of a thumbscrew allowed these to easily work loose while in use in the field. I would frequently find them dropping to the ground when I released them after use. This happened more often on the altitude axis when the handle was aiming down, but also occurred on the azimuth axis.
In addition, the handles are rigid which transmits vibrations from your hand into the mount. Vixen offers longer, flexible handles, with a thumbscrew at a cost of $25 each, adding $50 to the price of an already costly mount, for something that should have been included in the first place. Instead, I purchased replacements from Agena Astro for a very reasonable $18 for a pair of their 6.5” model (longer ones are available). These were a little longer than the originals, flexible to better isolate vibrations, and came with thumbscrews for a secure connection. The right photo below shows a comparison of the handles.
The only issue I ran into with these replacements was that the thumbscrew interfered with rotation on the altitude axis (left photo below). I was able to cut the threads a little shorter on the thumbscrew to allow it to clear the mount body (right photo below).
OK, after all these issues, how did the mount perform? Pretty well actually! One has to remember that this is a very lightweight mount with a fairly low load capacity and will not be as stable as its bigger brethren.
I tried it with both the ST80, weighing about 6 pounds including accessories, and the EON 72, weighing about 8.5 pounds. My tests were run with the legs extended roughly halfway. With either scope, when you went much above 100X, focusing became increasingly tricky. I had to change focus, wait till the view settled down to see how I did, and then try again. Lather, rinse, repeat. But again, I think that’s acceptable for the size and weight of the unit, and the kinds of scopes one would expect it to handle.
The clutches worked well, but needed some tightening beyond the factory supplied setting. At first, if the scope was a little out of balance it would sag. After tightening with the included allen wrenches, it worked very well. It was easy to move the scope by hand to the desired location and then use the slow motion controls for fine adjustment and tracking.
The slow motion controls were smooth, but as shipped, there was a lot of backlash. In an alt/az mount at low magnifications, this is mostly an annoyance, but it annoyed me enough that I was determined to improve it. The manual did not mention anything regarding gear adjustment, but after inspecting the gears, it became clear how to do so.
Each gearcase was covered with a small metal plate with a hole near each end to access a couple of set screws (left photo below). These set screws held the shaft bushings in place at each end. The bushings had an off-center hole for the shaft (right photo below), so if you rotated the bushing using the two little divots on its face, you would move the shaft a little to bring the worm gear closer or farther from the driven gear and take up the play. When done, just tighten up the set screws.
Another problem here - when I went to loosen the set screws, the metal place fell out and had to be glued back in when the adjustment was complete.
Acceptable weight capacity and stability for its size
Smooth slow motion controls
Handy built-in tool kit
Adjustable clutches on both axes
Each axis is rotatable to eliminate handle interference
Eyepiece tray is poorly designed
Manufacturing defect in how bolt was attached to eyepiece tray
Slow motion handles fell off too easily
Toolkit magnets needed to be glued in place
Gearcase covers fell off and needed to be glued in place
This mount has some nice features and fundamentally does the job it is supposed to. However, there were just too many issues that indicated poor quality control and manufacturing. For the cost I expected much better.
This mount could easily be made well worth the money if the eyepiece tray was redesigned, the slow motion handles were flexible and had thumbscrews, and if more attention was paid to quality control.
After spending time and money to improve the mount on my own, I will be keeping it for a travel mount. However, as shipped and for the price, I would not be able to recommend this mount to anyone.
I am not, nor have I ever been, in cahoots with any astronomy gear vendors, their employees, their families, or their cats.
- BinoGuy, SherwoodL, Philstin and 1 other like this