DV Info Net

DV Info Net (https://www.dvinfo.net/forum/)
-   Jibs / Cranes / Booms (https://www.dvinfo.net/forum/jibs-cranes-booms/)
-   -   Jib tilt and lean (https://www.dvinfo.net/forum/jibs-cranes-booms/52288-jib-tilt-lean.html)

Rick Pearson October 5th, 2005 02:20 PM

Jib tilt and lean
 
I have a problem that arises on regular occasion when using my crane.

The crane is made to tilt up and down by utilizing the tripod head where the crane is mounted. I've noticed that if I only do purely vertical moves everything is fine, but if I pan and tilt the crane simultaniously the claw ball that mounts the head to the tripod will slide and become unleveled, which obviously results in shots that end up leaning strangely.

I've also tried mounting the crane directly to the claw ball, but the same results occur. Anyone out there having similar problems? I'm using a heavy duty all metal head from gitzo mounted on a set of gitzo legs, this is definately not an issue due to using a DV tripod head. Any ideas of what could be causing this?

James Emory October 5th, 2005 02:33 PM

What kind of crane is it and can you provide any close up images of the fulcrum or wherever it's doing this when it's in service?

Rick Pearson October 5th, 2005 02:43 PM

it's a cobra crane II, and I don't have any images. But if you use your imagination to put yourself directly behind the crane as its mounted on the tripod and balanced perfectly... you would see that it's not sitting level from side to side. The legs are leveled, but the weight of the crane applied to the head, or the ball alone has caused it to lean to one side. I don't know if this helps, but that's the "picture".

James Emory October 5th, 2005 02:48 PM

Well, I have a full size Jimmy Jib that has similar issues. It has a rubber O ring between the fulcrum and the plate that attaches it to the tripod. Either the bolt is slowly loosening and creating a bigger gap between those two pieces allowing more play, the O ring is becoming compressed allowing the play or both. The reason I need to see picture is I don't know what a claw ball is.

Rick Pearson October 5th, 2005 03:22 PM

Here is a product that utilizes the ball I was referring to. In the description it is listed as a 100 mm ball base. It's merely a half ball that allows easy leveling of the tripod head by loosing and tightening a knob underneath the point of head attachment on the tripod.

http://www.bhphotovideo.com/bnh/cont...ughType=search

James Emory October 5th, 2005 03:27 PM

Okay. I'm familiar with the ball leveler but had never heard it called a claw ball before. Are you sure that it's designed to handle that much weight or weight that is distributed in that way? If your system has that hi hat, riser then the center of gravity is going to be top heavy and cause that leaning. If this is the case, that is not safe! If you don't have that riser, I bet that ball is slipping in the bowl because it's not designed to be used like that.

Rick Pearson October 6th, 2005 12:39 PM

No, I don't use the high hat or anything like it. I utilize an all metal high end fluid tripod head from gitzo. The leaning is coming from the ball element, but in my attempt to be sure and take the head out of the equation I did try mounting the crane directly to the ball leveler. Some times it slips and leans sometimes it does not.

I used the crane today for over three hours on a location shoot and it performed perfectly, but just the other day it leaned. I am sure everything is mounted the same, and everything is tightened correctly... but for some reason it loses it's horizontal center of gravity on occasion and I was hoping someone here had experience with solving a similar situation. Thank you for your help and willingness to help in the matter. I do appreciate it.

James Emory October 6th, 2005 01:10 PM

I can't figure out what it could be without seeing pictures of the rig as you have it configured. Can you take some pictures of it at the fulcrum and joining points in both configurations? I'm not really familiar with what a Cobra looks like. Is the head seperately adjustable from the arm. Mine is and you have to adjust the side to side to level after you have leveled the fulcrum.

Rick Pearson October 6th, 2005 01:14 PM

Yeah, I'll get some pics. Today's shooting schedule was overly busy so I didn't take any setup shots this time around, but the next shoot I'll snap a couple stills and throw them up, I don't know when that will be though. Thanks.


All times are GMT -6. The time now is 04:22 AM.

DV Info Net -- Real Names, Real People, Real Info!
1998-2024 The Digital Video Information Network