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Melvin Baggs March 9th, 2010 02:44 PM

Center of Gravity on Tripod Head
 
How important is it that the cameras COG is inline with the COG of the Tripod Head?

After you attach all of your non-stock accessaries (Monitor, wireless receiver, SG mic/softie, etc) to the camera its COG will change. How do you redetermine the cameras new COG to put it in line with the Head of the Tripod?


Thanks in advance for your response.

Melvin

Chris Soucy March 9th, 2010 03:56 PM

Hi Melvin............
 
Quote:

Originally Posted by Melvin Baggs (Post 1497193)
How important is it that the cameras COG is inline with the COG of the Tripod Head?

Exceedingly.

Failure to ensure that they are correctly aligned means the counterbalance system will be unbalanced and will not function correctly.

Quote:

After you attach all of your non-stock accessaries (Monitor, wireless receiver, SG mic/softie, etc) to the camera its COG will change. How do you redetermine the cameras new COG to put it in line with the Head of the Tripod?
Easy.

Mount the camera onto the head. Ensure that the tilt lock and tilt drag controls are set to OFF or Minimum (whichever applies) and that the counterbalance control (if there is one) is set likewise.

Move the camera to approximately the centre of the plate travel and lock it.

Level the camera and head horizontally front to back. Let go of the pan arm.

If the COG is more than slightly out of alignement, the head will either tilt forward or backward.

If it tilts forward, unlock the head plate and move it backward a tad. Re - lock, set the head level and let go the pan arm.

If it tilts backwards, do the reverse.

After a couple of goes the head/ camera will stay horizontal and you have found the correct positioning for COG alignement.

To double check, tilt the head slightly forward and observe. Then tilt it back and observe.

The head should fall both forward and backward at equal speeds.

Set your counterbalance (if available) and the job's done.

If your rig configuration doesn't change for extended periods, it's worthwhile painting a white mark on both the head and the head plate to indicate the correct plate location to save having to go through all the above rigmarole every time you load the camera.


CS

PS: If you check out the piccie of yours truly testing the 3 AS head, you'll see the white mark I painted on the head and plate.

http://www.dvinfo.net/features/vinte...od-3-of-4.html

Jon Fairhurst March 9th, 2010 05:49 PM

Hi Chris,

I read your entire review yet again, and it's a treat.

One comment though... didn't Vinten change to a lighter spring some time after your review? Page 2 mentions that it's a bit stiff for lighter cameras. If they made an improvement, you might add an author's note in the vicinity of the obsolete paragraphs.

Thanks again for the review!

Chris Soucy March 9th, 2010 06:44 PM

Yeah, a good idea...........
 
I'm actually waiting for Peter Harman to send me one of the new springs so I can do some objective measurements of just how much difference it makes.

Hopefully it isn't too far away.

When I've got the figures I'll knock up a little something for CH to amend the existing review.

Glad you liked it, BTW.


CS

Charles Papert March 9th, 2010 06:51 PM

To add to this, understand that counterbalance requirements will change as the camera's CG raises up above the platform also (remember that CG refers to the actual center of the entire camera assembly in three dimensions). When you start using vertical offsets and risers as can be the case with DSLR's, the CG will rise and this will require more counterbalancing out of the head. The easiest way to test for this is to tilt the camera 3/4 of the way forward. The camera should ideally sit in place; if it starts to tilt up, you need less counterbalance; if it falls forward, you need more. Adding drag will help manage this as a stopgap but to get the most out of the head, it should be in the best possible balance at all times.

Melvin Baggs March 10th, 2010 12:57 AM

Thanks again for your guidance and support.

Just to think a year ago I knew nothing about video, yet, now I can give advise to new-er-bies, with confidence, the right direction to go in their selection of Tripod Systems. Vinten, without a doubt cause I chat with the TOP DOGS who make and write reviews on the instruments. Makes me feel special!

Melvin

Dale Guthormsen March 14th, 2010 05:52 PM

Melvin,


Imagine what you will know in 5 years!!!!


Dale


80 % of my knowledge comes from this forum and all the great people on it!!!

Jon Braeley March 18th, 2010 11:06 AM

One helpful extra thing I do is to get the camera rigged and put on the QR plate. Then I place this on a rod - a round pencil is fine on a tabletop, and you can check the COG balance point by rolling the rig back and forth. I then mark this point on the plate and place this in the center of the tripod. Then I find I hit the balance more accurately when I set my conterbalances.


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