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-   -   good tripod for Cobra crane? (https://www.dvinfo.net/forum/jibs-cranes-booms/18005-good-tripod-cobra-crane.html)

Lorinda Norton December 5th, 2003 10:49 PM

good tripod for Cobra crane?
 
I bought a 6' crane a while back. Now I need a tripod to go with it.

Today, UPS delivered a used tripod--old Bogen 3066 fluid head with what looks like 3193 legs. I paid $500 to a private seller. I really liked the feel until I noticed it had been broken in shipping. Not only did it break, (on the side with the tilt control) 2 bearings and a piece of the plastic ring fell out of the head. The seller insured it, so UPS told me they'll pick it up.

My questions: Is there an equivalent out there that compares in price? And is there any sense in trying to repair this one? I've looked online at B & H but don't shop well looking at pictures. Any advice would be really appreciated!

Mike Rehmus December 6th, 2003 01:33 PM

Bogen should be able to repair the setup for not a lot of $ compared to a new one.

I use a Bogen 3050 with a large non-fluid head of theirs for my Cobra with the extension. I think this is the minimum setup but just about the largest setup one can use with the Cobra due to it's small tripod plate.

I'm going to either extend the plate or make a new one (the original is a bit flimsy . . . it bends) and then put it on a large Samson 5302 tripod and 5230 head. Old but weighs about 50 lbs with 2"+ leg diameter, very big ground pads and a monsterous dolly.

Picture at http://www.transfilm.com/graphics/equipt/qshercul.htm

I don't think you can get too big for a crane support.

Lorinda Norton December 6th, 2003 02:15 PM

<<<-- I don't think you can get too big for a crane support. -->>>

Mike,
You're the second person in as many days to tell me that! Must be true.

I feel pretty dumb--did a search online yesterday but didn't see a Bogen site. After your reply I tried a little harder and, there it was! I'll call them on Monday.

As you probably know, they have this handy chart that shows just what you want to know, like the service cost, a replacement model (516) and new-for-old trade in price.

Thanks so much for the help, and best wishes on your soon-to-be monster set up!

Chris Mah December 6th, 2003 03:58 PM

I have the Cobra crane with the 10 foot arm and use a Manfrotto 351MVB/Bogen 3182 with a 501 head on it. I think this is one step down from the used one you bought. This is the minimum I would use as you don't want your gear to come crashing down.

The other thing I highly recommend is a dolly to mount it all on. There's no practical way to move the tripod and crane without a dolly.

I made a portable dolly for about $50 in parts from Home Depot. I also sometimes use it with a 14" external monitor and this easily sits on the dolly platform.

Robert Knecht Schmidt December 6th, 2003 07:53 PM

The skateboard wheel + PVC dolly sold by the ProMax (the Cobra Crane folks) is also fairly serviceable.

For my Cobra Crane I use a Bogen 3246 Black Professional Tripod with 3066 Fluid Head. With this setup, also consider getting an additional 3158 Mounting Plate for the 3066 head (+$30) to allow for quick changes with the Cobra Crane.

Lorinda Norton December 6th, 2003 08:07 PM

Thanks, Chris. I hadn't thought about moving the stuff around, and Mike's monstrous dolly talk flew right over my head as a necessity. We'll give it a try.

I know what you mean about a minimum. When I first got the crane we mounted it on a tripod with a 3126 head and 3011 legs. We could see it actually bending a little; hence, this current search.

Robert,
Good idea on that extra mounting plate. I saw one on the B&H site and never gave it another thought.

All kinds of great ideas here!

Kieran Clayton December 6th, 2003 08:16 PM

Bogen do actually have a site with hundreds of pictures (but no prices).. It's http://www.Manfrotto.com because Bogen is only the US brand name.. To the rest of the world they're known as Manfrotto tripods. Make sure if you're searching you use the Bogen product code search box (yup, they decided to give all the Bogen tripods different product numbers too).

Kieran

Mike Rehmus December 6th, 2003 08:56 PM

The one thing you have to be careful of with the Cobra Crane is the tripod mounting plate, besides flexing and allowing the crane to tip sideways, has some short dimensions between the threaded holes (which are also too close together (I like to use 2 bolts to hold the setup)) and the vertical plate to which the arm is attached. That means that as you try to elevate the arm, the backside will hit bits and pieces on the tripod.

It just barely clears my Bogen as it is. I have to move the Pan handle to the left side but that means I can stand between the arm and the handle and control boom elevation and camera tilt all at the same time.

When I build a new boom mounting plate, I'm also going to add a monitor mount so that I can look at the monitor and straight over it to the camera. Now if I can just figure out how to hold the monitor level while I'm moving everything else.

The other 'thing' wrong with the design of the Cobra crane is that the load of the crane setup is offset from the centerline of the tripod. Tripods were not designed to work with asymmetrical loads and I think this might eventually cause problems. I think the arm needs to be held between two upright plates that are centered over the tripod head. If they are tall enough plates, there would be no restriction on elevating the arm.

Well, maybe there is a third issue with the Cobra Crane. One gets the tilt action on the crane head by tilting the tripod head. This gives a kind of funny motion to the camera head as not only is the crane moving in an arc, but it's support is too. So the crane does not scribe a perfect arc at the camera end as you elevate it and tilt the camera. It is kind of a scolloped path.

I'm sure you know that the entire approach to elevating a camera does not lend itself to shallow depths of field with a wide-open lens.

I'm actually thinking of replacing the wheels with an air bearing so I can get very smooth motion and no artifacts from the wheels changing directions. Don't need much air pressure, just volume. A shop vacume should work just fine. And I can use the vac to clean the stage first so I don't raise any dust!

BTW, the crane can act as a very interesting Steadycam. Get everything balanced out and then operate the camera by handling it as it is attached to the crane. If you can get the action to move in an arc around you (not too obvious in the final picture) the motion is pretty nice but still has a certain amount of liveliness to it that a dolly shot will not. Certainly helps to have a LCD screen on the camera for this. Vertical motion is well-controlled too.

Lorinda Norton December 7th, 2003 12:16 AM

Actually, I didn't know ANY of this stuff. We only tried the crane once and decided to wait for a beefier tripod. I'll print off your findings and we'll check them out as soon as we can.

Though I like the concept of "air bearing" as opposed to wheels, I gotta admit, I don't understand a word of what you're saying. That's okay, for now; however, if you get something like that set up I'd sure be interested in seeing it.

Mike Rehmus December 7th, 2003 12:46 AM

An air bearing is just the concept that low-pressure air trapped between two surfaces will carry a load equal to the pressure in pounds per square inch time the number of square inches of the smaller of the two surfaces.

Well, in a practical system, one cannot really seal the edges or one has the equivalent of an inner-tube and that kills the mobility. So you supply a continuous stream of air so that as it escapes around the edges, it is replaced.

A one square foot plate supplied with 10 psi will theoretically lift around 1440 pounds. Gotta have the plates close and supplied with air through many small holes. But it can be done. And very large loads are moved in this manner.

Some warehouses have the air supply under the floor with balls held from below against holes in the floor. As a plate carrying a load passes over the balls, they are pushed down and air is released between the plate and the floor. A single person can move tons this way and the load is just setting on a plate. Course the person better understand momentum really well!

Lorinda Norton December 7th, 2003 01:05 AM

*sigh* Now you're really hurting my brain! Seriously, I kind of understand it, in a very general sense. At least the remark about the momentum wasn't lost on me. :)

Re-reading your last post I realized we did encounter the problem with the crane slipping sideways and wondered about using two bolts, so thanks for the confirmation.

Now if I can just decide what to do about the tripod!

Can't tell you (and the others) how much I appreciate this input. It will really help us down the road.

Mike Rehmus December 7th, 2003 01:14 AM

The problem with the two bolts is that the crane plate is set up for one large and one small bolt. Cannot use the camera hold-down screws here as they run into each other.

And although there is enough room for a small and large bolt pair, they need a washer under the head to keep them from chewing up the bottom of the tripod quick release plate. Those washers have to be flattened (cut part of the circumference off) so they will fit next to each other. Overlapping isn't a good idea.

Oh, and the bolts have to be necked down right under the heads so that they will fit into the slot in the quick release plate.

It's a pain but can be avoided by modifying the Crane's tripod plate by drilling and tapping or drilling and using a nut with the bolt. You can spread the parts out.

Better yet, consider drilling new holes through the quick release plate and getting away from the problems with the center slot altogether.

Lorinda Norton December 7th, 2003 01:46 AM

Can't anything be easy? :-)

I'll run all this past the one guy I know who could pull off such feats. Thanks again.

Chris Mah December 7th, 2003 01:51 AM

Here are some other things I've done with my Crane that might give you some ideas.

I've run three wires up inside the tubing. I could have just attached them on the outside but I like to keep everything neat and tidy and it makes setup really easy. One is for video, another for a Varizoom controller and the final for audio from the headphone jack. The audio is kind of irrelevant though since you can't control the audio settings once the camera is in operation. I just figured I'd run the wire since I was doing the other two.

The pan handle is moved to the left side as Mike has mentioned and I've attached the Varizoom here. For a monitor I normally use an old Sony Hi-8 camcorder that has a 3.5" swing out LCD. It's mounted on a three way Manfrotto still camera head which is in turn mounted on a Manfrotto Super Clamp.

The Super Clamp is attached to one of the tripod legs and I can pivot the camera at any angle for viewing. The only drawback is that I have to have that leg facing me at all times. I'm thinking of designing something that'll clamp to the top of the Crane mounting plate so it's always pointing at me in the right direction.

Where my camera normally goes I've mounted a quick release plate. This allows me to remove the camera in about two seconds to transfer right onto my tripod.

Occasionally I've also mounted a Manfrotto 128RC micro fluid head to the end of the Crane. As Mike has noted, it makes for some very interesting floating type shots. I can work the pan head in the normal way and move the Crane in a vertical and horizontal axis at the same time. The only thing is that it moves in a very slight arc instead of perfectly up and down. I've even dragged the dolly behind me as I was following someone on a stage one time. More to reposition the camera instead of trying to get a smooth shot.

Lorinda Norton December 7th, 2003 02:28 AM

I think it's Letterman who would say, "That is something!"

Love the idea of the quick release for the camera. The other is kind of a pain.

As for you guys' floating shot/Steadycam setups, I'm having a bit of trouble seeing each of those scenario's in my mind. If either of you ever has time to share pictures, I'd sure like to see them. Actually, I'd like to see shots of all that has been mentioned--rather a visual learner, I guess.


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