Jump to content


Photo

Modifications to my Porta mount

  • Please log in to reply
18 replies to this topic

#1 TONGKW

TONGKW

    Apollo

  • -----
  • Posts: 1074
  • Joined: 16 Jan 2007

Posted 08 June 2013 - 04:26 AM


I use the OTA from my 6SE on a manual AltAz mount for star hopping. I want a lightweight setup but with 6” aperture. I often need to ride on a bus or other public transport to a dark site and so I need to put the OTA and accessories in a backpack and carry the tripod by hand.
I have bought a Vixen Porta mount and adapted it to suit my purpose.
First the base of the Porta is changed for use with a medium sized photo tripod. For this I use a few of my tripods (20-year old Gitzo 1415 aluminum/Feisol 3471 carbon fiber/Manfrotto 071).

K W TONG
C8+CG5 GT, TSA102+HEQ5 PRO, MK67+Voyager, NexStar 6SE, C5+Mizar K, WO ZS80FD+Kenko NES, Megrez 72FD+Kenko KDS, Mini Borg 50, PST

Attached Files



#2 TONGKW

TONGKW

    Apollo

  • -----
  • Posts: 1074
  • Joined: 16 Jan 2007

Posted 08 June 2013 - 04:28 AM

With the C6 mounted on to Porta in the original configuration, the finder scope is at the bottom on the left side which is not convenient for me. This is not a problem with a refractor OTA with tube rings.

Attached Files



#3 TONGKW

TONGKW

    Apollo

  • -----
  • Posts: 1074
  • Joined: 16 Jan 2007

Posted 08 June 2013 - 04:29 AM

The Porta is a little too heavy and bulky as it is with the original side arm. I have made use of a piece of 3/8” thick Aluminum angle to replace the side arm.

Attached Files



#4 TONGKW

TONGKW

    Apollo

  • -----
  • Posts: 1074
  • Joined: 16 Jan 2007

Posted 08 June 2013 - 04:31 AM

With the side arm on the Porta replaced by the aluminum angle, the finder shoe on the C6 is now at the top on the right side where I install a red dot finder. I also attach a 9x50 RACI finder to the dovetail.
I like to first point the OTA to the general direction of the sky object to be observed with the red dot finder then locate it with the 9x50 RACI finder.

Attached Files



#5 Jon Isaacs

Jon Isaacs

    ISS

  • *****
  • Posts: 43423
  • Joined: 16 Jun 2004
  • Loc: San Diego and Boulevard, CA

Posted 08 June 2013 - 06:38 AM

Hi:

Interesting modifications, it is certainly more compact than the standard Portamount.

How stable is the scope on the medium duty photo tripod?

Jon

#6 TONGKW

TONGKW

    Apollo

  • -----
  • Posts: 1074
  • Joined: 16 Jan 2007

Posted 08 June 2013 - 07:33 AM

With the C6 OTA mounted, there is no noticeable difference in stability between the original and the modified Porta. For acceptable stability, the photo tripod has to be at least of size Series IV.
As can be seen in the photo below, the reduction in size is considerable. Otherwise I cannot put everything in the backpack.

Attached Files



#7 tomharri

tomharri

    Messenger

  • *****
  • Posts: 469
  • Joined: 19 Sep 2008
  • Loc: USA

Posted 10 June 2013 - 02:33 PM

How did you get the verticle rotator off the side arm? Do you have to destroy the neat blue cover to get at the holddown screws?

Attached Files



#8 TONGKW

TONGKW

    Apollo

  • -----
  • Posts: 1074
  • Joined: 16 Jan 2007

Posted 10 June 2013 - 07:33 PM

I did manage to lever off the “Vixen” cover disc with minimal damage with a thin bladed screw driver.
It was put on with strong adhesive.
I believe a new replacement disc is available from Vixen.

#9 munchmeister

munchmeister

    Ranger 4

  • *****
  • Posts: 318
  • Joined: 04 Apr 2012
  • Loc: Fort Collins, Colorado, USA

Posted 12 June 2013 - 11:20 AM

Awesome portable package. I love it. All in a backpack and transportable on public transport. Very clever modifications. How difficult was it to dis assemble the porta head? And can you tell us where you obtained the aluminum angle? This is really 'grab-n-go' at its finest.

#10 RAKing

RAKing

    Fly Me to the Moon

  • *****
  • Posts: 6222
  • Joined: 28 Dec 2007
  • Loc: West of the D.C. Nebula

Posted 12 June 2013 - 01:10 PM

This is great work! :bow:

The size reduction is incredible. It's amazing what we can adapt when circumstances force the issue.

Cheers,

Ron

#11 munchmeister

munchmeister

    Ranger 4

  • *****
  • Posts: 318
  • Joined: 04 Apr 2012
  • Loc: Fort Collins, Colorado, USA

Posted 12 June 2013 - 02:44 PM

TONGKW, I am just wondering if you considered other alt az heads when you developed this for travel. I've looked at the Desert Sky Astro DSV-M which is a very small head, though it does not have slo-motion controls, just friction. Also the Stellarvue M2 would be small, though it might need some additions, too, to allow for mounting a C6. Just curious if you considered these others.

#12 bilgebay

bilgebay

    Skylab

  • *****
  • Moderators
  • Posts: 4118
  • Joined: 06 Nov 2008
  • Loc: Turkiye - Istanbul and Marmaris

Posted 13 June 2013 - 02:51 AM

How did you get the verticle rotator off the side arm? Do you have to destroy the neat blue cover to get at the holddown screws?



I drilled a small hole where the dot on "i" is in "Vixen" logo. Then used a wire hook to pull the cover off. It's hard to notice the hole and the cover os not damaged at all.

#13 bilgebay

bilgebay

    Skylab

  • *****
  • Moderators
  • Posts: 4118
  • Joined: 06 Nov 2008
  • Loc: Turkiye - Istanbul and Marmaris

Posted 13 June 2013 - 02:55 AM

Very nice mod! Good job!

The only thing that worries me is that the weight is off the tripod center now but a C6 shouldn't be a problem I think.

Enjoy!

#14 TONGKW

TONGKW

    Apollo

  • -----
  • Posts: 1074
  • Joined: 16 Jan 2007

Posted 13 June 2013 - 05:03 AM

The Porta mount is quite easy to diamantle. The hardest part is the removal of the plastic “Vixen" disc without too much damage. Then with the supplied tool kit, the Porta mount can be diamantled in about 5-10 minutes.
----
The 4” x 4” x 3/8” aluminum angle is obtainable here in Hong Kong from metal shops. I have just bought a few more pieces for use by my other club members. The shop owner just use an electric table saw to cut off the pieces each at 2.5” long from a long piece at a cost of about five US dollars per piece.

Attached Files



#15 TONGKW

TONGKW

    Apollo

  • -----
  • Posts: 1074
  • Joined: 16 Jan 2007

Posted 13 June 2013 - 05:06 AM

Besides the Porta, I also have other manually operated AltAz mounts all have slow motion control (such as Voyager, Manfrotto 410, Manfrotto 405, Kenko KDS, Mizar K). Each of these is used for a different OTA.
I prefer to have slow motion control on both axes as I am not good at nudging the OTA at high magnifications.

#16 Agatha

Agatha

    Apollo

  • *****
  • Posts: 1161
  • Joined: 04 Jun 2012
  • Loc: Coulee Region, Wisconsin

Posted 13 June 2013 - 08:57 AM

I really like your mods for the Porta . Very nice work. I have more than one Porta also. It's a great little mount.

Best,

#17 tomharri

tomharri

    Messenger

  • *****
  • Posts: 469
  • Joined: 19 Sep 2008
  • Loc: USA

Posted 26 June 2013 - 06:56 PM

Liked your mod to the Porta Mount II.
Decided to modify the mini porta mount since it is selling for only $159 shipped. Holds my 90mm f/6.7 really well.

Attached Files



#18 Midnight Dan

Midnight Dan

    Voyager 1

  • *****
  • Posts: 11175
  • Joined: 23 Jan 2008
  • Loc: Hilton, NY, Yellow Zone (Bortle 4.5)

Posted 26 June 2013 - 07:55 PM

Nice job, TONGKW! Love the way it all fits in that backpack! :bow:

-Dan

#19 TONGKW

TONGKW

    Apollo

  • -----
  • Posts: 1074
  • Joined: 16 Jan 2007

Posted 27 June 2013 - 05:00 AM

I have also modified a mini Porta for use with my C5.

K W TONG
C8+CG5 GT, TSA102+HEQ5 PRO, MK67+Voyager, NexStar 6SE, C5+Mizar K, WO ZS80FD+Kenko NES, Megrez 72FD+Kenko KDS, Mini Borg 50, PST

Attached Files








Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics