Sorry in advance about the length of this post, but it's a complex subject with a lot of pitfalls, and I know it rather well. If you want any more information feel free to PM me and I'll tell you anything you want.

I have built and flown a number of smaller multicopters, and done some aerial photography with them quite successfully. That said, there are a number of things you need to know, as there are some significant problems with this, mostly legal.

In the UK, remotely piloted aircraft under 150kg are, or were, classed as model aircraft. There is a specific set of regulations around RC model aircraft, which was updated in 2010 in a way that makes this sort of thing much more difficult to do.

Before that point, there were essentially 3 classes of model aircraft based on total weight, not including fuel. This is ignoring niceties such as power source, fixed vs rotary wing, and the like. Models up to 7kg all up weight could be flown anywhere with permission of the landowner, and had no altitude limit, except in controlled airspace, unless with the permission of the controller of that airspace. IE, air traffic control at an airport. In controlled airspace the limit was 400ft AGL. The controlled airspace in question would normally not be at an actual airport, but more likely in the immediate area of one, such as on the landing approach. Uually you'd avoid such locations like the plague anyway.

Models above 7kg AUW, but under 20kg AUW, had a 400ft altitude limit everywhere, except in controlled airspace with permission, etc, or unless the area you were flying had a CAA exemption. One of my local clubs has this sort of thing for large jets, which can fly up to 1500ft AGL.

Models above 20kg AUW, but under 150kg, had the same limitations, but also require a flight plan to be filed.

A large hexcopter with a good DSLR and enough batteries to give a sensible flight time can easily exceed the 7kg point.

Recreational use of model aircraft fitted with cameras was, and still is, completely legal. Commercial use was much more involved, as you required commercial aerial photography insurance, which was difficult to get until a few years ago. Eventually, it became fairly straightforward, and in theory you could approach the company that underwrote the BMFA recreational insurance and get commercial aerial photography cover, which was around £200 per year. You needed to give them some risk assessment stuff, a business plan, and so on, but in principle it was fairly easy. I was very close to doing it myself.

In 2010 the relevant rules were changed. Model aircraft were classified differently. The weight classes and altitude limits stayed the same, but now they are also classified as either a Small Unmanned Aerial System (SUAS) or a Small Unmanned Surveillance System (SUSS). An SUSS is any SUAS outfitted with sensors for collecting remote data, which includes any form of camera.

Recreational use of SUSS types is still pretty much the same, but they doubled the minimum distances you're legally allowed to fly adjacent to someone not directly involved in the flight. Commercial use of an SUSS, however, has become nearly impossible.

The details may have changed a little since I last checked about a year ago, but basically you had to get trained by a CAA-certified instruction company (of which there were none at the time) on each specific aircraft that you were going to use. The aircraft themselves had to be certified in some way, which was rather vaguely laid out. Then you had to file a flight operations schedule covering out when you were flying, where you were flying, things like that, at least two weeks in advance, and pay a fee of something like £120, each time.

It pretty much killed the commercial remote photography market overnight. I knew several companies that were doing this sort of thing and they all went out of business within a year. There still are people doing it, but as far as I can see, most if not all of them are on rather dodgy legal ground if something goes wrong.

The intent was to cut back on the problem that the CAA saw of anyone who wanted to buying a big multicopter (it was more or less aimed specifically at them), sticking a camera on it, and chucking it into the air in the middle of a city.There were a number of incidents where people with no knowledge of the rules were doing some really quite foolish things, like flying next to heathrow. Because the things are so easy to fly, especially the high end ones, which are more or less point and shoot, quite a lot of people with more money than sense were playing with them and they thought it was all going to end in tears.

Unfortunately, it was as usual a case of baby with the bathwater.

Now, knowing all that, from the actual mechanics of the thing, there are lots of options. The place to start would be working out the total payload you intend to carry, then finding a suitable platform. Duration of flight is an important metric as well. Vibration is the biggest problem, as you can't glide a multicopter So you always have the motors running, and unless all the props are very well balanced it will vibrate, and even when they are it's still present to a degree.

Undoubtedly the best flight controller system on the market is from Mikrocopter, although it is also one of the most expensive. You can get some amazingly cheap ones that work surprisingly well, although they're much more basic. I have one controller that was about 25 quid that works better than the first one I bought two and a half years ago that was over £300. The frames start at around a tenner if you hunt around. Motors, props, speed controllers, batteries, and the like vary from under a hundred pounds for a complete system to pretty much as high as you want to go.

At a bare minimum you would require BMFA insurance, which is about £32 per year. It gives a significant level of third party cover for aeromodelling, but as I said above only covers recreational use.

pca