Vixen Porta II

[astro_al]

Having now had regular use out of the Porta II mount for three months I thought I would write a quick review.

I procrastinated about this purchase for some time knowing that I could by a Berlebach tripod and Castor mount combination for the same price. The Berlebach setup was my previous grab-and-go mount which I loved but foolishly sold thinking I wouldn't need it anymore after putting in a permanent pier and AZ-EQ6. Not buying this again felt like a risk, but in the end the idea of the slow motion controls won out over dual mounting; and the decision went Vixen's way. 

The version of the Porta II mount purchased is the one with the APP-TL130 tripod. I went with this as I had read that the stock tripod was the weakest link when operating with a scope approaching or at the recommended 5KG weight limit. I also picked up a second-hand Losmandy saddle even before the Vixen arrived as I wanted to use both Vixen and Losmandy dovetails. The mount came with a carry bag which I haven't had the need to use.

The mount was purchased to use with my FOA-60Q and FC-76DC. Both are lightweight OTAs (< 2KG) but I only user a binoviewer these days so the total weight all in is about 4.2KG when using a 2" Herschel wedge and about 3.8KG for night time use.

First impression was that it looked the part but I quickly became annoyed with the flexible slow motion controls falling off. Swapping the thumbscrews for socket head bolts was an easy fix. I leave the altitude control permanently attached but have to remove the azimuth control when collapsing the tripod for storage. The APP-TL130 tripod is nice and compact and I like that it has spiked feet that can be simply hidden by unscrewing the rubber feet.

After about a month of use I started to feel the slow motion controls bind. On inspection I realised that both the altitude and azimuth axes were loose and now allowed enough play for the weight of the telescope to cause the two sides of the rotating parts to rub. The azimuth axis was worse, presumably due to the off-set design of the mount. While ergonomically this is helpful when looking at objects near the zenith, it does mean that a well balanced scope in the altitude axis is rear heavy on the azimuth axis.

I disassembled the azimuth axis, checked everything and tightened the main nut. This sorted the issue, but only briefly and I was soon back to rough slow motion controls. I repeated the disassembly but this time in both axes, and this time I tightened each nut significantly.

Not unexpectedly this reduced the free-flowing movement of the mount and it now takes more effort to align the scope on a target, typically one hand on the scope and one on the tripod. This is actually OK for my type of viewing. I am more of a lunar/planet/solar observer when it comes to grab-and-go anyway so I am not darting around the sky. The slow motion controls are buttery smooth again and so far the play in the axes hasn't returned.

When it comes to magnification on solar system objects, I am happiest with an exit pupil of about 1mm when using the binoviewer. For the scopes the mount was purchased for this means a magnification range of about 55 to 90x. The Porta II and APP-TL130 handle this well but I find that over 100x the dampening time increases noticeably, especially with the F15 tube of the FOA-60Q. I typically use the tripod with the first section half extended. With the first section fully extended damping time increases.

I have recently picked up a FC-100DC which for night time viewing is pretty much on the weight limit for the Porta II and about 400G over with the Herschel wedge added for solar viewing. In its tightened configuration the Porta II head feels like it will support the scope, but the dampening time is too high for my liking, even at lower magnifications with the tripod at its lowest. I suspect that using the Porta II with the heavier Vixen HAL-130 tripod would improve this so I may go that way if I find myself wanting to use the FC-100DC on this mount. This would become slightly less of a grab-and-go setup though, however the main reason for the purchase of the Porta II is to view objects not visible if I set up on the permanent pier - like the sun first thing in the morning.

I do like this mount. I prefer the slow motion controls to nudging the mount along and it now works great for what I use it for. However, I think if I wanted to do more than observe solar system objects then I would have a different opinion as the need to over-tighten the axes to eliminate slop when using scopes below the weight limit is not great.

My conclusion is that if you enjoy the freedom of flinging your scope around to all areas of the sky and have a payload of more than 3KG then look elsewhere. I would choose a Berlebach Castor, Giro, Ercole etc. for this. If, like me, you stick to the bright stuff when away from GOTO and you like slow motion controls then the Porta II is worth a look. I would also be interested to see how the Skywatcher AZ5 compares.

Clear skies.

Al

 

[JeremyS]

Good review @astro_al - a well balanced analysis! I take my hat off to you for your thoroughness and objectivity.

I have the Vixen Porta 1. Fine for my Lunt 50, although not the smoothest of movements. But wouldn't want anything much larger on it. I find the Tak FC 76 DCU is too much for it (left pic). My SW AZ5 is much better for that scope (right pic). Yes the tripods make a difference, but it's mainly the mount itself.

Edited April 16, 2020 by JeremyS

[astro_al]

Thank you @JeremyS.

39 minutes ago, JeremyS said:

Yes the tripods make a difference, but it's mainly the mount itself.

That's good to know. The AZ5 looks good on the Berlebach tripod, very nice. I wonder if it would go in the APP-TL130 tripod....

[mikeDnight]

I've used the AZ5 at length with an FC100DC,  and although it coped, it wasn't good. The AZ4 is better by far, providing its been lubricated properly. It's just a shame the AZ4 doesn't have slow motion controls. Having said that, I never use the short and weak Chinese tripods as they are the weakest link, but instead I use the much stronger Vixen alternatives. I have to admit I could never tolerate the Vixen Porta or Porta ll as they both vibrated like a tuning fork. That was years ago now and may be they've ironed out the vibration issues. I've managed some very high power observations using the AZ4 as a grab and go, but only if I can't get the target from my observatory, where I use a driven Vixen GP.  

Congratulations on the new DC. 

 

[astro_al]

49 minutes ago, mikeDnight said:

Congratulations on the new DC. 

Thanks @mikeDnight. One previous (careful) owner . I am loving it on the AZ-EQ6, much less scary to mount than the FS-152.

[mikeDnight]

2 hours ago, astro_al said:

Thanks @mikeDnight. One previous (careful) owner . I am loving it on the AZ-EQ6, much less scary to mount than the FS-152.

I agree!  Although I loved my FS152, my back gave way one night as I was lifting it onto the G11, which at the time was about 6' 6" high to the dovetail. I slid down the pier in agony, but I didn't let go of the FS152. I thought then that sooner or later I would not be so fortunate, and I don't mind admitting I'd have cried like a baby if I'd dropped a  £10,000 refractor. I think I sold it along with the mount and pier very shortly after that, and cheaply too! Part of me misses the FS152 and the FS128, but I have to admit I've never used a scope as much as I used the FC100DC. ☺

 

[Paz]

Nice review of the Porta 2. I use one and have an AZ4 to compare it with. The Porta 2 gets a lot more use as I like the slow motion controls, but the AZ4 is more solid.