Balancing an 8’’ dome (filled with air)

Ikelite 8’’ dome port

Ikelite body for Canon 10D

I tried this material in my bath tub. The air in the the dome brings the whole housing into a 45 degree horizontal position. (lens looking at the sky.)

Am I supposed to balance it? I know about the Near-neutral buoyancy but this time it’s about the orientation of the housing.

I moved this to the appropriate forum.

I too am trying to figure out a way to customize the balance of the housing, especially since my new housing will be used for video occasionally. I'm not familiar with Ikelite mounts so I don't know how much weight it will take before the weight affects how the o-ring seats.

The best way to get it balanced without making the housing negative is to add a little bit of weight to the bottom of the dome lens shade and some buoyancy to the housing body. This should tip the housing forward enough. You'll have to experiment with the balance of weight and buoyancy floats. For buoyancy float suggestions, search the forum for Stix and foam as keywords. Good luck.

When I needed to balance out my housing - I used an ankle weight around the extension ring. Of course, I wouldn't recommend it with a housing that doesn't have a secure port mount.

Cheers

James

An ankle weight sounds scary. The Ikelite port is held by 2 tiny plastic pieces.

I think i'll fix 2 (90 degree) metal bar (fixed to the handles) that will hold weight without touching the body or the port.

If I can get my rig neutral, I'm so happy I don't care about balance!

If I can get my rig neutral, I'm so happy I don't care about balance!

I second that ... now if it's neutral, isn't it already balance ?

No.

A system can be neutral but not balanced. If the center of buoyancy is not above the center of gravity the system will rotate until it is.

Cheers

James

To add to what James said, trust me, having a well balanced rig keeps your mental and physical balance as well... especially now with the 5D2 shooting video as well.

To add to what James said, trust me, having a well balanced rig keeps your mental and physical balance as well... especially now with the 5D2 shooting video as well.

I agree but let me rephase it, if it's neutral, isn't it easier and lighter to manipulate the rig into position, so balance or not would be less significant ? I suppose if it's not balance, one hand shooting would be very difficult ...

Good point and question, will watch this thread and answers with interest.

I've a Ikelite 8" it's neutrally bouyant but tips/rotates heavily.

After a 2 or 3 hour dive (Rebreather) I suffer very badly with wrist strain from fighting it vertical all the dive.

I've thought about some more weight in the base and then arm floats to give a turning moment but not done anything yet.

Cheers,

Richard B.

I agree but let me rephase it, if it's neutral, isn't it easier and lighter to manipulate the rig into position, so balance or not would be less significant ? I suppose if it's not balance, one hand shooting would be very difficult ...

Depends a lot on how not neutral the system was and how much righting moment the dome port adds to the system. In my hands, a slightly neutral housing that sits upright means a lot less arm and wrist strain than a neutral housing with a big dome port that needs to be twisted. YMMV

Bill

Good point and question, will watch this thread and answers with interest.

 

I've a Ikelite 8" it's neutrally bouyant but tips/rotates heavily.

After a 2 or 3 hour dive (Rebreather) I suffer very badly with wrist strain from fighting it vertical all the dive.

I've thought about some more weight in the base and then arm floats to give a turning moment but not done anything yet.

 

Cheers,

Richard B.

Hi Richard,

Just reading ur comments and noticed your set up very similar to mine. Just about to use the 10-22 in the ikelite housing with 8" dome port, but the gear sleave and focus ring don't fit. I see you have a similar wide angle and wondering what I am missing? Is there a specific extension or additional gear sleave? Only came with a standard size one?

Cheers

Steve

Hi Richard,

Just reading ur comments and noticed your set up very similar to mine. Just about to use the 10-22 in the ikelite housing with 8" dome port, but the gear sleave and focus ring don't fit. I see you have a similar wide angle and wondering what I am missing? Is there a specific extension or additional gear sleave? Only came with a standard size one?

 

Cheers

Steve

Hi Steve,

To avoid Hijacking responded here :-

http://wetpixel.com/forums/index.php?showtopic=28619

Cheers,

Richard B.

Ikelite 8'' dome port

Ikelite body for Canon 10D

 

I tried this material in my bath tub. The air in the the dome brings the whole housing into a 45 degree horizontal position. (lens looking at the sky.)

 

Am I supposed to balance it? I know about the Near-neutral buoyancy but this time it's about the orientation of the housing.

If you can add bouyancy to the rear of the set, neoprene sleeve for flasharms for example, to raise the rear. and then weight to the bottom to neutralize the bouyancy.

What sort of techniques are people using to add weight in order to compensate for the dome always wanting to pull upwards?

I would much rather have a negative camera set up than one that I have to fight to keep level, I find the dome port a little frustrating to dive with at the moment

Photo's of additional ways to attach weight would be great

What I have used to balance a plastic dome port is go to your local tire place and buy stick on wheel weights. They come in a strip with adhesive on one side.

I just move the strobes forward a few inches to balance the rig with the dome.

My Nauticam 8.5" dome definitely likes to face the sky. I have only taken it on 7 or so dives while on a trip to Hawaii a few weeks ago, so I didn't really mess with it too much. It's definitely more positive overall too (Nauticam NA-D810 housing, 70mm extension ring, 16-35/4 lens) than with my 170mm dome and 15mm fisheye. I may try it with less floats on the arms, but I don't think weights on the extension ring are a good idea and I'm not too keen on putting wheel weights on the shade of the dome either. Hmm.