Vixen Mobile Porta Mount Review
Twenty years ago, I bought myself a mount when I got back into astronomy. That mount was a Vixen GP. It was a beautifully made thing for its modest price. Fifteen years later when I sold it, it worked and looked like new.
I replaced the GP with another Vixen, an SX2. I like it even better Ė one of my favourite bits of astroí gear. I use the SX2 in pretty much all my scope reviews. So, when I wanted a light and really portable alt-az mount, Vixen was the obvious choice.
This Vixen Mobile Porta is the replacement for the old Mini Porta, an excellent little mount, as was the larger Porta I once owned. It seems ideal Ė a light alt-az with push-pull and slow-motion controls, meant to hold up to 3Kg with a standard Vixen dovetail Ė exactly what I need for small peripatetic scopes like the Tele Vue Ranger and Takahashi FS-60Q.
At A Glance
2.4Kg incl. tripod
3.5Kg (Vixen) 2Kg (Me)
Data from Vixen.
Whatís in the Box?
Unfolding the Mobile Porta mount head.
Design and Build
The mobile Porta shares styling cues with other current Vixen mounts and looks much like the old Porta I owned, even down to the white powder coat. Unfortunately, this is an illusion.
The basic design is similar to the Porta too Ė a single arm push pull fork head and a built-in Vixen dovetail plate, with variable tension and slow motion controls. I find this to be a very flexible design for an alt-az Ė push it into position and then make fine adjustments and track with the slo-mo handles.
One obvious difference between the Mobile Porta and the older models is that the fork isnít a single casting, but has a folding part so it packs up smaller. The mobile Porta is extremely light Ė just over two kilos. With a little 60-80mm scope your whole package should be less than 4 Kg. Sounds great, for both travelling and grab-n-go.
Finally, itís worth noting that basic Vixen scopes of old often got pared as a package with a Porta, like the A70LF you see below. This was pretty lucky for a beginner because the Porta was a quality thing. Nowadays the hapless beginner is likely to get a Mobile Porta with their Vixen long-focus achromat or small Newtonian Ė not so lucky. Why so?
The problem is that to get to get the weight or cost down (or both), the materials used in the Mobile Porta are much flimsier than the old Porta. Itís made of the cheapest plastics and bendiest metal components. If you squeezed the tripod legs too hard theyíd snap. The slightest knock marrs the plastic. The tripod spreader, eye piece tray and tripod clamps are so thin theyíre like toy-stuff and wonít last more than a few outings.
The odd thing is the way theyíve copied the look of the Porta, but not the function, like some rip-off Rolex. Take the slo-mo handles. On my old Porta these were solid metal rods held on by grub screws. The ones on the Mobile Porta look identical, but are chromed plastic and push on. They bend so much it would be easy to snap one just pushing it into place. A few times on and off for travel and theyíll break for sure.
All this might be OK if the Mobile Porta was super-cheap, but itís not. At 2/3 the price of a Porta, itís terrible value for such shoddy stuff. But does that poor quality matter in use? After all, the design seems sound. Letís see.
Original Porta mount Ė solid and robust.
Adjusting altitude and azimuth tension is easy with the supplied Allen key.
In Use Ė Daytime
The Mobile Porta is quick to set up and get observing. Just unscrew a thumb wheel, fold out the fork arm and get your dovetail clamped in. The only adjustment is the push-pull friction on each axis and thatís easy to do with the supplied Allen keys (see photo). I canít deny that super-lightness is a benefit: a small rig would be one-hand portable by a child.
But once youíre out and observing the trouble starts. Because itís obvious without even looking through the scope that the whole thing flexes and bends as you push it up and down, even with the friction controls at their lightest, even carrying the lightest scopes. It feels like it might break.
Once viewing things get worse. I tried the Mobile Porta with various scopes during the day, for spotting and bird watching through the windows and in the garden. All the scopes I tried weighed ~1.5-2Kg (itís supposed to handle twice that), including a Borg, an FS-60C and Q and a TV Ranger. Only the FS-60C was vaguely usable owing to its very short tube. The others vibed so much it was hard just getting focus beyond low powers. And all the while I was afraid Iíd snap something off (and Iím not heavy handed).
Mobile Porta carrying ~2Kg of Takahashi FS-60Q.
In Use Ė Photography
The mobile Porta is too vibey for all but the quickest Moon snaps, but I successfully took some images of a setting daytime Moon with the FS-60C and flattener, albeit using a light camera body. Being able to move the manoeuvre the whole rig around steps and narrow paths to get the best angle was a bonus of the Portaís incredibly light weight.
Capturing the setting Moon with FS-60C/Vixen Mobile Porta.
In Use Ė The Night Sky
At night, the Mobile Porta is best for star sweeping at low powers. I tried the Moon at 101x with the FS-60C and it was perfectly possible, including using the slow motions to track, but the vibes took a long while to damp and focusing was a bit tricky.
It was usable though and again I did appreciate the ease of carrying it as a complete system Ė less than 4Kg all-in: mount, scope, diagonal, Nagler.
The mobile Porta is not the best piece of astroí kit Iíve bought recently. Yes, itís light. Yes, it looks good, but Ö
The design seems basically sound. The problem is the materials. At anything above 40x the vibes are terrible, except with the shortest OTAs. The fittings on the tripod are of such poor plastic they would likely break after a few outings or a few knocks in the dark.
To be clear, this may look like a Porta or my SX2, but quality is at a totally different level. I would have wondered if it was a rip-off, a counterfeit, had I not bought it from the official importer Ė it really is that flimsy.
Sadly, Iíll be a bit wary of buying Vixen gear in future. Thereís flawed equipment and gear thatís just not good enough. This sort of quality on a Celestron Travel Scope is more excusable because itís cheap, but the Mobile Porta lists for almost as much as a TV TelePod mount head (really? really?) and honestly you could buy a tripod of that quality for the price of a drink.
Essentially, the Mobile Porta is a decent design thatís just been too cheaply produced and isnít good enough. I bought it for my own use, but sent it back.
The Vixen Mobile Porta is not really recommended, unless you need the lightest dovetail-compatible mount for a tiny scope and donít care how long it will last.