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 – one of my favourite bits of astro’
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 – a light alt-az with
push-pull and slow-motion controls, meant to hold up to 3Kg with a standard
Vixen dovetail – exactly what I need for small peripatetic scopes like the Tele
Vue Ranger and Takahashi FS-60Q.
At
A Glance
|
Mount |
Mobile
Porta |
|
Weight |
2.4Kg
incl. tripod |
|
Capacity |
3.5Kg
(Vixen) 2Kg (Me) |
Data from Vixen.
What’s
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 – 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 – 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 isn’t a single casting, but
has a folding part so it packs up smaller. The mobile Porta is extremely light
– 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, it’s worth noting that basic
Vixen scopes of old often got paired 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 – 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. It’s made of the cheapest plastics and bendiest metal components. If you squeezed the tripod legs
too hard they’d snap. The slightest knock marrs the
plastic. The tripod spreader, eye piece tray and tripod clamps are so thin
they’re like toy-stuff and won’t last more than a few outings.
The odd thing is the way they’ve
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 they’ll break for sure.
All this might be OK if the Mobile
Porta was super-cheap, but it’s not. At 2/3 the price of a Porta, it’s terrible
value for such shoddy stuff. But does that poor quality matter in use? After
all, the design seems sound. Let’s see.
Original Porta mount – solid and
robust.
Adjusting altitude and azimuth
tension is easy with the supplied Allen key.
In
Use – 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 that’s easy to do with the supplied Allen keys (see photo). I can’t
deny that super-lightness is a benefit: a small rig would be one-hand portable
by a child.
But once you’re out and observing the
trouble starts. Because it’s 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 (it’s 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 I’d snap something off (and I’m not heavy handed).
Mobile Porta carrying ~2Kg of
Takahashi FS-60Q.
In
Use – 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 Porta’s incredibly
light weight.
Capturing the
setting Moon with FS-60C/Vixen Mobile Porta.
In
Use – 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 – less than 4Kg
all-in: mount, scope, diagonal, Nagler.
Summary
The mobile Porta is not the best
piece of astro’ kit I’ve bought recently. Yes, it’s
light. Yes, it looks good, but …
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 – it really is that flimsy.
Sadly, I’ll be a bit wary of buying
Vixen gear in future. There’s flawed equipment and gear that’s just not good
enough. This sort of quality on a Celestron Travel
Scope is more excusable because it’s 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 that’s just been too cheaply produced and isn’t 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 don’t care how long it will last.
