Vibration isolation (which includes step inputs like bumps) requires mass, springs and damping. Essentially you set up a system of a mass suspended on springs, damping being needed to reduce amplitude around the system resonate frequency. The design needs to concentrate on achieving a resonate frequency well displaced from the forcing frequencies likely to be encountered. So a general principle is a large mass on soft springs. Sitting in the chair is one means of adding mass. Letting air out of the tyres provides a soft suspension (but limited by size of bumps). Hand-holding the camera provides some more spring and damping but can also add more vibration (depends on operator skill). Smoothing out the bumps is a common approach (eg. dolly rails). How smooth it needs to be depends on the subject and the style. If tracking someone walking (or otherwise in action) you can get away with a lot. If tracking in on a stationary subject you really do have to be smooth (unless style is jerky hand-held). Small longer wavelength shakiness can be removed with Deshaker (and even surprisingly effective in smoothing walking with camera), but it can't remedy frames blurred by shakes.

I was wondering if anyone has come across a shock absorbing mount for the camera that would reduce subtle vibration.
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Absolutely

John

I'm sure sitting in the chair and using your arms as 'shock absorbers' would help but I was looking for a situation where the camera was mounted on the wheelchair itself so I was hoping someone had a kind of poor man's steadycam setup that would assist the process. Still thinking..

Genie

Just keep that mount away from hot lights and it'll work just fine.

Maybe you need to describe your needs in more detail. There are designs for "poor man's steadicams" but these aren't easy to use (just as the real thing isn't easy to use). You seem to want a dolly and a wheelchair is a reasonable substitute. Let air out of the tyres (but certainly not all of it), put a sandbag or two on the seat and mount your camera on top. Wheel carefully (dolly-grips get paid good money for a good reason). Once you understand the principles of getting smooth tracking then the rest, while not easy, can be achieved.

Thanks Serena, there is some good tips there - yes I am looking for a mobile dolly platform that could act as a tripod, a steadycam so I can film as I gently move, and also as a base to carry all my gear which fills two large boxes plus my laptop.
I was going to check out a wheelchair on Monday but I think it has solid wheels, I may need to find one with inflatable tyres.
The only idea bouncing around in my head was to make a rubber mounted frame across the handlebars on the wheelchair to mount the camera which would help cushion small vibrations as I film, perhaps acting as a kind of subtle spring? Dunnno, still thinking..

Genie

We have a number of the Miller Pro Dollies, basically just a way to put soft wheels on a tripod, they're better than the cheap ones with hard wheels but still it doesn't take much of a bump in a floor to get a wobble in a shot.
That's the advantage of running on tracks, no more bumps to start with.
The wheels on the wheel chair being much larger will help. There's a number of 4 wheeled camera dollies that the 35mm guys use that aren't overly expensive that might be more suitable, I think wheel chairs aren't that cheap either.

But if you want to persist with the idea then ordinary bungy cords used for tying down things on roof rack can work as well as anything. The trick as Serena mentioned is getting the period of the system right and well dampened, get it wrong and it can make matter worse so try adding weight and changing the tension on the rubber. The other aid that might be worth a look at is the Cinesaddle.

Of course at the end of the day, if it was all so simple a lot of people would be out of a job. You see the biggest problem is the magnification factor of having the camera effectively on the end of a pole, a 1mm bump in the wheels becomes a 10mm movement of the camera and if you're in tight on a long shot that's really bad.

Bob.

Thanks Bob for the tip on the cinesaddle - I'd never heard of it before, did a quick google and it turns out their head office is a few suburbs away from me here in Perth, Australia. Ain't the internet wonderful!
The other concept I thought of was something like the suspended easyrig - but as you say every mm movement makes ten and if it works a lot of people end up in soup kitchens.
Wheel chairs are actually quite cheap - you can buy them for $200 australian new and they look okay on the net. I'll pop through on Monday and check them out - then it might be a different story!

thanks Reece.

Have you tried a bean bag?

I wouldn't go anywhere without mine. Sit it on the floor, on a table (perhaps even in a wheelchair) push the camera into it and it will stay there.

I use Glideshot's track and dolly and it gives wonderful results. It is a bit expensive but I couldn't ask for better dolly shots.

Great thread. Jim's contribution was absolutely stellar.

The idea of getting a perfectly smooth ride reminds me of the classic Saturday Night Live sketch, where they did a takeoff of the 1970's commercial showing a diamond cutter cutting a stone in the backseat of a Mercury Marquis as it was driven over railroad ties. In the SNL skit, the diamond cutter was replaced by a Hasidic Jewish mohel, and the diamond by a infant boy. In both the original and the parody, everything turned out perfectly.

Now that's a smooth ride!

Reece,
if you're in Perth then you should also check out the Wally Dolly!

I believe Mr Wally is in Perth. We have one and they work very nicely. Good thing is it packs down into a small bag. I'd suggest getting an extra length of track, the standard 3M is a bit short.

Bob.

Since you don't already have a wheelchair I reckon you should look at other mechanisms. Bob has suggested good available rigs. If you are interested in building a dolly or steadycam then you should check out
www.dvcamerarigs.com
for well designed, well instructed and cheap stuff you can make with little equipment and few skills.
If you want a dolly without rails, check out local garage sales for bicycles and use the wheels (kids size, about 18 or 24"). Around here people put them out with the "hard rubbish", so they're free.

Edit: the dolly in "Killer Camera Rigs That You Can Build" is rather cheaper than the Wally Dolly but doesn't fold up so neatly. Basically it uses PVC pipes for track that you can join, without bumps, into any length you wish.