As some one said, if you don't have a dust collector, you become the dust collector, and I am fond of breathing.
First, there are several types of dust filtering systems.
One is a dust mask or positive pressure dust mask with motor and filter. Does a pretty good job of keeping dust out of your lungs but not out of your shop.
Another is the 'air scrubbers' which is a motorized filter that you put up in your shop to remove the tiny particles that hand around in the air for a couple of days and do the most damage when inhaled. They don't remove bulk dust from sanding.
There are the shop vacs, which I think are the same as your cam vacs. This is basically a vacuum cleaner. Fairly good for collecting dust from sanding and other small tools. Fairly noisy, and not that efficient.
Then there are the dust collectors. These are bigger machines which are intended to get most of the dust at the source. Most are 1 hp motors or bigger. There are a multitude of designs and types, and filtering systems to go along with them, but they move a lot of air. You can get a smaller one on wheels to move around from machine to machine, or a centralized system that sits in one spot and you set up duct work. A remote starting switch is really handy (keep it on a clip on the wall, or it will get lost in the shavings). They are not really good for sucking up shavings as there is usually a lot of bulk, and they can clog up your maching and fill your bag quickly. A shovel and rake are better at that.
There are single stage and two stage machines:
Single stage is a motor with an impellor (fan blade) and everything sucked up through the hose goes through the impellor into the bag. Fine if all that goes through is dust, but shavings, rags, chunks of wood and other things lying on the floor can do a lot of damage to the impellor.
Two stage is a cyclone or funnel which sorts out all the big bulk things, and only the fine dust goes through your impellor. There are a number of options from plastic lids that fit onto a metal garbage can, to fancy metal cones.
The filters are another important thing. The standard has been fabric which does a good job of filtering out the dust. They used to be all 5 micron bags, but there are now some that go down to 1 micron. The newest thing is the pleated paper filters. The biggest advantage they have is that they have several times the surface area of the cloth bags, so you get much better air flow, even when they start to fill up. Most of them are 1 micron filters.
As for venting the air out side or inside, the 5 micon bags will vent harmful dust back into the shop. Cloth bags when you first fire them up will have a poof of dust. The 1 micron bags will vent virtually no dust back into the shop. Venting to the outside of the shop is no problem in nice weather, but in the winter, it can cool off your shop in minutes.
The most important thing is to get as much dust at the source before it gets into the shop. A 4 inch hose will get most of it from small things like pens or boxes. If you go to bigger bowls, or hollow forms, or longer spindles, you want a hood or bigger vent than your hose. Check out the sanding hood at the Oneway lathes site. You can makea box of sorts, or there are some thing available in the stores.
I don't know what you have available over there, but check out Oneida Dust collectors. I don't have the link, but you can web search them.
robo hippy
and should show the differences 8) I'll keep my finger off the 'buy it now' button :lol: 
