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Questions on attaching Porta II Alt-Az head to good tripod

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#1 cworl

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Posted 03 March 2017 - 11:07 PM

I have a Vixen Porta II Alt-Az mount that came with a tripod.  The mount head works well, but the tripod is not nearly stable enough for use with my 15+ pound Comet Hunter Mak-Newt.  I have a heavy duty tripod that I would like to use, so I'm thinking of getting the Vixen 3942 tripod adapter.  The adapter has a 1/4" screw hole, and the heavy duty tripod has a 3/8" screw, so I could get a 3/8"-16 female to 1/4"-20 male adapter, but I'm not sure if that would be stable enough since the adapters I've looked up have a much smaller diameter than the top of the tripod and the mount head.  

 

Also, I thought I read somewhere that there are three bolts that attach the adapter to the tripod head, but the head I have did not come with any bolts; the tripod that came with it attaches with one large screw with a tightening knob.  Does anyone have experience with attaching this particular head to a tripod that has a 3/8" screw?  Do you need to use 3 bolts as well as the 1/4" to 3/8" adapter, and would such a screw size adapter be stable?



#2 leveye

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Posted 03 March 2017 - 11:33 PM

I had no trouble attaching the mount base to other wood legs using wingnuts,washers and bolts from the older tripod head. Worked great.

 

 

IMG_7874.jpg


Edited by leveye, 03 March 2017 - 11:35 PM.

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#3 msl615

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Posted 04 March 2017 - 12:02 AM

I have the Porta II attached to a Vixen Hal 130 SX tripod and it is extremely stable. It uses the single 3/8 bolt. The key is that the Porta II uses the Vixen SX standard 45mm hub connection, compared to the older Vixen 60mm hub design (such as on the original SP, GP, etc). If you can find a SX hub (with the 45mm system), you should be able to connect your Porta to any tripod that can accept the hub. 



#4 AhBok

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Posted 04 March 2017 - 09:57 AM

I would contact Mr. Starguy for advice on this.I will say my Portamount 2 on a Hal130 tripod works great with my 100mm F9. The weak link for the stock Porta is definitely the tripod. Fix that, and you may love your mount.
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#5 Agatha

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Posted 04 March 2017 - 04:33 PM

Please keep in mind that the Porta II is a 10mm thread.  It is not a 3/8 ...close but not the same.  



#6 cworl

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Posted 04 March 2017 - 05:10 PM

Please keep in mind that the Porta II is a 10mm thread.  It is not a 3/8 ...close but not the same.  

The Vixen 3942 Camera Tripod Adapter is supposed to have a 1/4" thread hole to fit to a 1/4" camera tripod.  So my thinking was if I got a 1/4" to 3/8" adapter, I could attach it to my sturdy Bogen tripod, but I'm not sure if I need other screws or bolts to attach the adapter to the Porta II head.  Mine did not come with any bolts, but the tripod adapter picture shows 3 holes where I suspect I'd have to find the right sized bolts.



#7 Jon Isaacs

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Posted 04 March 2017 - 08:04 PM

The Portamount head attaches to the hub with three bolts,  the Portamount ll uses a single bolt,  very close in size to the Bogen tripod center bolt.  Linda cautions it's 10 mm and not 3/8-16..

 

Myself,  I doubt a Portamount ll even on a stiff tripod would handle the Comet Hunter Mak... Here is a photo of what is almost certainly the most robust tripod ever put under a Portamount..  At some point,  the mount itself has to also be up to the task. 

 

Jon

 

4412595-TeleVue NP-101 on Houston Fearless CN 2.jpg


#8 Agatha

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Posted 04 March 2017 - 09:56 PM

I think Jon is correct in that your telescope's weight may be pushing it on the Porta.  

 

If you do decide to try it there are various options.  Here is a picture of two of my Porta mounts.  The original (older) Porta is on the left and the newer Porta II on the right.  The black piece on the right side (which is what makes it a Porta II)

comes off with the 3 screws...one is mostly removed.  

 

I have the Vixen 3942 adapter (the black piece on the left).  When you remove the 3 screws from the Porta II version, the photo adapter will simply take it's place.  I have one because I want to adapt my older Porta to a different tripod with a flat top.  But I will drill and tap a new center thread to 3/8 most likely.  

 

The Porta II, as mentioned, has a 10 mm center mounting....the one on the right.  Oddly enough, the base without the black piece has a 3/8 threaded hole (marked with the blue tape)

 

 

image.jpeg

 

Here are some more ideas in similar threads:  http://www.cloudynig...a-photo-tripod/

 

http://www.cloudynig...d-azeq6-tripod/

 

And, if you feel like spending more $$, there is this...the Porta will plug right into it, and it is way more solid than the original tripod.  https://www.optcorp....ipod-25161.html.    And there are wooden ones also.

 

grin.gif   Hope this isn't too confusing.   

 

 

Good luck to you.


Edited by Agatha, 04 March 2017 - 09:57 PM.


#9 cworl

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Posted 05 March 2017 - 01:40 PM

Thanks Linda for that detailed description with pictures.  The Porta II description when I bought it said it has a maximum capacity of 20 lbs, so I thought it would be ok with the Comet Hunter, but the Porta II manual says it has a maximum loading weight of 11 lbs, so like you and Jon said, it probably does not matter what tripod I use.  Some day I hope to get a heavy duty EQ mount to do AP, but I had hoped the Porta II could bridge the gap in the mean time (and it's certainly a lot lighter and easier to set up for a quick viewing session).  For wide field viewing, my set up as is works pretty well, but for powers over 100x, the vibrations make it difficult to achieve fine focus. 



#10 Jon Isaacs

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Posted 05 March 2017 - 03:24 PM

Thanks Linda for that detailed description with pictures.  The Porta II description when I bought it said it has a maximum capacity of 20 lbs, so I thought it would be ok with the Comet Hunter, but the Porta II manual says it has a maximum loading weight of 11 lbs, so like you and Jon said, it probably does not matter what tripod I use.  Some day I hope to get a heavy duty EQ mount to do AP, but I had hoped the Porta II could bridge the gap in the mean time (and it's certainly a lot lighter and easier to set up for a quick viewing session).  For wide field viewing, my set up as is works pretty well, but for powers over 100x, the vibrations make it difficult to achieve fine focus. 

 

I think a more robust tripod would help for sure.. Since you are using a Newtonian, the tripod can be short.  I would just make (or have made) a set of fixed length legs like those used on the Vixen Polaris and probably the Super Polaris etc.  Much easier to make and stiffer.. 

If you were around here, I would just loan you that Houston Fearless tripod.. It was designed for the old TV cameras that weighed hundreds of pounds.. 

 

Jon



#11 RTLR 12

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Posted 05 March 2017 - 04:13 PM

I use my Porta II mounted on my Celestron CG-5 2" SS tripod. I mounted my 115mm refractor at 15# and found that it was way too much weight to be practical nor was I confident that the mount could structurally handle that much weight.

 

Stan

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#12 cworl

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Posted 06 March 2017 - 12:40 AM

I removed the black adapter from the Porta II head and attached my solid tripod to the 3/8" screw hole on the bottom (albeit off center).  While it's not a perfect solution, I'd estimate that this set up reduces vibrations by at least 50% compared with using the original flimsy tripod that came with the Porta II.  


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#13 WyattDavis

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Posted 01 December 2018 - 05:34 AM

I use my Porta II mounted on my Celestron CG-5 2" SS tripod. I mounted my 115mm refractor at 15# and found that it was way too much weight to be practical nor was I confident that the mount could structurally handle that much weight.

I am also looking to get my Porta II on to a better tripod than the stock aluminum unit that came with it and see that there are options on Mr. Starguy - HAL130, Berlebach Report, etc. In other news, I am tempted to try a manual GEM mount as well (in creeps insanity...) and was wondering about the Celestron CG4. The top of its tripod looks like this:

CG4 Tripod - Top.png

 

I have read elsewhere that a CG5 uses a single M10x1.5 bolt to attach to its tripod:  

https://www.cloudyni...x-16/?p=6497952

 

and that the Porta II does as well:

https://www.cloudyni...bolt/?p=5169465

 

Two questions I would appreciate some help with:  

  • Does the CG4 use the same bolt size - M10x1.5 - as the Porta II?
  • Will the CG4 tripod's alignment peg shown in the photo above work with the Porta II or will it keep the mount from fully seating on the top of the tripod?

All input appreciated!



#14 Simon B

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Posted 01 December 2018 - 03:41 PM

Two questions I would appreciate some help with:  

  • Does the CG4 use the same bolt size - M10x1.5 - as the Porta II?
  • Will the CG4 tripod's alignment peg shown in the photo above work with the Porta II or will it keep the mount from fully seating on the top of the tripod?

All input appreciated!

 

The bolt is the same, yes, but the north alignment peg will get in the way - you could grind it off, then it would be compatible

 

Vixen use a 45mm diameter hub for many of their mounts including the Porta II. The CG4 tripod has a 60mm diameter hole, so there'll be about a 7.5mm gap between the hub and the hole, but I don't think that will matter, the bolt should hold it securely in place


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#15 WyattDavis

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Posted 01 December 2018 - 03:52 PM

Good to know. Thanks for the info!


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