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f1nutter

Achieving neutral buoyancy on camera setup

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Hi Guys, long time no post!

 

I am looking for some advice or experience on the "best" way to achieving neutral buoyancy for my rig. I am still a novice and managed to get most of my gear second-hand, and at a fraction of the new cost.

 

I have a Nikon D700 with Aquatica housing and 9.25" dome port. I have the 16-35 f4 VR lens and extension port. I also have two Inon Z240 strobes on 5" and 8" Ultralight arms. I have a macro lens but no port and no plans to shoot macro - at the moment.

 

This setup is very front buoyant and a pain in the wrist to tilt down at any angle. It is also heavy. I weighed it in a wheelie bin full of water, and it weighs about 690grams (1.5lbs). After an hour, I start to notice! It also affects my balance as I move the rig closer of further away from my body.

 

I have had a look at the large Ultralight buoyant arms, probably 8" and 10" to achieve 690g of lift and balance the rig. I have also looked at the StiX floats - 4 jumbo or more, smaller floats.

 

I have used this rig a couple of times in the Red Sea, and I am going to the Maldives in June and want to get this "better" than I have now. My concern is that the buoyant arms are expensive and there is no guarantee this will achieve the right buoyancy.

 

Can anyone suggest the best way forwards, please?

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So to confirm, its 690g negative AND rear heavy (front comes up)

 

I would, get float arms to get rid of the -690g and then pop to a tyre fitters and buy some sticky lead weights for wheel balancing and add to the bottom of your dome.

 

Have a look at the Nauticam 150x90mm or 200x60mm carbon float arms for a large lift, but small(ish) size.

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I'm just not excited about adding weight to achieve trim; I'd rather find a way to add buoyancy. My rig is heavy enough out of the water without adding more weight! One option is to add a horizontal float arm between the left and right handles.

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I'd go with Stix floats, they are durable and highly configurable, and cheap enough to experiment with.

 

A set of of 4 floats provides buoyancy of 160g (small), 350g (large), 680g (jumbo).

 

If you're shooting wide angle the arms will be behind the port and so offset the dome buoyancy.

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I would go with the stix floats as well. They fit nicely on the ULCS and similar arms. (and weigh almost nothing). I wouldnt be too afraid about extra weight from the lead strips. If the setup is more or less neutral, its all about the balance. If you fit the weights at the underside of the shade the tilt is the largest. (he does use 11,5 oz / more then 300 grams of lead).

 

Probably best to first try with the floats, and then see if the problem is still there...

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Some of this advice seems a bit bizarre - adding floats AND weights. I think all that is needed are floats to achieve neutral buoyancy of the whole rig - or am I missing something?

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Some of this advice seems a bit bizarre - adding floats AND weights. I think all that is needed are floats to achieve neutral buoyancy of the whole rig - or am I missing something?

 

The problem with a neutral rig, is that it could potentially be neutral in the water, however due to large domes, the pivotal point is not centred - but more towards the front. So it will float Dome side up (not what you want, as you will always be fighting the rig to keep it pointing forwarding. So adding counter weights to the dome will bring it back down.

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I do not know what type of strobe activation you are using, but an electrical sync cord represents 100-150 g of weight added to the system.

 

If you have 2 strobes, changing to optical fibre can help you with 200-300 gr less (it is not directly because the volume of the electrical cord give you a small impulsion and if you need an optical trigger inside the housing (not being the internal flash) it will also add some weight to the system).

 

But it will help. And it will be much less bulky that adding floater for that weight. (bulkier rig will make it harder to handle underwater, specially with currents, and sometimes it will mess with the strobe positioning). It might not get you rid of the floaters, but you will need less of them.

 

The less the better. It is a good principle.

 

BR

 

Pedro Alves

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So I bought a set of jumbo and a set of large Stix floats. The jumbo should get me to near neutral, and then the large to trim and offset any weights I add to the dome.

 

 

If I get the chance, I will try to put the rig in a wheelie bin full of water so see if it is at least neutral.

 

 

As an engineer at heart, my thoughts turned to trying to find the center of balance and buoyancy of each component - dome, housing, strobes - so that each part is perfect and changing strobe position or port will always end in a neutral, well balanced system. But not right now!

 

 

To answer a few of the comments above (thanks for these) I only shoot wide-angle at the moment so will move the arms back to offset some of the dome buoyancy.

I use wired strobes, simply because the housing came with wired bulkheads and a Heinrichs & Weikamp TTL converter.

 

 

Hopefully, I will report back after my trip. Thanks for the help.

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As an engineer at heart, my thoughts turned to trying to find the center of balance and buoyancy of each component - dome, housing, strobes - so that each part is perfect and changing strobe position or port will always end in a neutral, well balanced system. But not right now!

 

 

 

Wow, sounds like quite a project, f1nutter....... sounds a bit like the Quest for the Holy Grail.

I sure look forward to hearing more :crazy:

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