At first glance the use of balloons in aerial photography would appear to be a fine idea. You don't need to wait for a breeze, helium's not that expensive and balloons of various sizes are available almost anywhere. Well, as they say, "the devil is in the details". When you actually go ballooning problems begin to emerge.
It turns out that a 36" diameter balloon (the largest readily available in my town) will just barely lift the lightest camera rig. In fact, given the variations in inflation pressure at my local balloon store, this is by no means a given!
|Digital Camera Rig||Weight (oz.)|
|Agfa CL-20 digital camera|
|2 x AA batteries|
|wire frame to hold it|
Even with both balloons filled up you'll just barely have enough lift for a small digital camera.
You can't buy helium tanks easily, but you can rent a "4 foot" tank for a year at $60, plus $55 for the regulator/gauge assembly. Each helium refill costs $55. This contains 244 cubic feet of helium, or about 20 refills of a 36" balloon. I think all this must be making some assumptions about temperature and pressure, but these are the terms in which the local helium dealer expressed it. You can rent a "2 foot" tank as a 3-day rental for $28.
One last practical issue is how you transport the balloon. 36" is a BIG balloon. I can just fit it into the rear hatch of my compact wagon.
A more fundamental problem is that balloons are not very stable in the wind. I guess the round shape just gets pushed every which way. Basically, balloons are a tool for zero wind days. Alternatives would be to make the balloon a different shape like a blimp, insert it in an envelope and frame like a rigid airship, or attach it to a kite (see Nature, Vol. 36, the "Kite balloon").