Hi All :

Just wondering.
I´ve bought a new Canon A-570IS + Canon WP-DC12 Water Proof Housing.
The full set has a positive flotability of 68 grams in fresh water. In salt water, the positive flotability is even higher.
Besides of these, there is a separate set of weigths to make it negative flotability.

I understand that for the beginner, my case, I prefer positive flotability.

The builder does not know if the diver will use it in fresh or salt water, the question is why so positive (68 grams).

Hi

I’m not sure there’s any particularly good reason why most Canon housings are postively bouyant.  Obviously its a function of their size and weight (and the weight of the camera too).  I suppose that cost saving comes in to it, in that to make housings of the typical size of Canon’s housings neutral or slightly negatively bouyant would require the use of greater wall thickness (hence more weight for the same volume) or the addition of steel or lead weights.  In either case it would make their housings more expensive.  In a market segment that is highly cost conscious, this probably doesn’t appeal to Canon.  As you observe, you can buy an optional weight kit for the canon housings, allowing you to tune the bouyancy.  A moderately practical person could make their own weight kit for the housing - I suspect most good DIY stores or marine chandlers would carry a stainless steel bolt that would screw into the tripod socket on the housing.  The bolt can then be used to attach small plates of stainless steel or lead to the housing.

Personally I find postive bouyancy of any camera rig a nuisance, because unless you are holding the rig, it tends to float up and get in your face.  I always use a lanyard with my rigs, so I can let go of the camera if I need to.  I don’t like wrist straps because the rig then flaps about near my hand which I prefer to have unencumbered.  Lanyards do have a slight downside of entanglement risk, and this is especially the case with a positively bouyant housing.  I have had a lanyard wrap around my reg hose once, but it wasn’t especially difficult to sort out.  If you make your rig slightly negatively bouyant, the risks of entanglement with a reg hose are massively reduced.

If you prefer positive bouyancy, then fair enough - you need to be happy with your rig, and not necessarily be swayed by the opinions of others.

hope that helps.

Hi Graham :

Thanks for your comments.
I did my own weight with lead and a stainless steel M6 screw, keeping still the positive flotability but very slight in fresh water.
Cost is a point, however, the price of the housing is comparative to the price of the camera itself or even higher. Adding a stainless steel screw and a piece of lead would not make any difference. Canon could charge a few bucks more for the housing with the weights avoiding people with practice to make their own. In this particular case, the Canon WP-DC 12 Housing is exclusive for that Canon A-570IS camera, so the weight balance is always kept.
Plastic wall thickness is a function of depth and preasure.
I agree that such a positive bouyancy is a nuisance. A small weight should be the difference to tune buoyancy for your particular preference or fresh/salt water.