Maybe not performance in any noticeable degree, but it can still fall off, and to prevent it to fall of you have to drill some holes, use some bolts and so on. You are very much affecting the structure.
Just a week ago, a Sonex owner here got an answer form Sonex Aircraft about mounting a stall warning in the wing leading edge (Cessna style). The answer he got was that the leading edge is a very important load carrying structure, and they could not advice such a modification because they had never done such a modification themselves.
Here in Oz, they take it very strictly… you can’t even mount a GoPro without an Engineering Order… :-(
We’ve done a thread about this earlier. Click here
For allowance of external devices: if you can remove it in flight, then it is allowed. If not removable in flight, it’s not allowed or it is a modification and then you need some paperwork. Does it affects the performance of an aircraft? Sure it will, but can you feel it or even measure it? I don’t know and it does depend on the place where you mount it on the aircraft.
You are very much affecting the structure.
Not if you bolt to a tie-down ring with something like this:
Jacko wrote:
Not if you bolt to a tie-down ring with something like this
Good point. I have never had or used a go pro in my entire life. Maybe I should include camera attach points on my Onex.
The Sony camera is far more aerodynamic than a Go-Pro. This should also result in less aerodynamic buffet on the camera.
I googled on an Onex. Low wing, so best place for the attachment is underneath the wing, far out. If you can provide power there, even better 
But if you are providing power, you should have a means of remotely turning it off (in case of fire etc). The obvious way is a dedicated CB but if say you are powering it from the wingtip lights cluster (to save running a long wire) and using a DC-DC converter, put in a relay so that turning on some part of the wingtip light turns off the power to the camera (a clever trick I got from another pilot here).
I found this some time ago: CAP1369
It applies to Annex 2 aircraft.
Jacko wrote:
Not if you bolt to a tie-down ring with something like this:
I think someone asked FSDO about a camera mounted to a tie-down point (retrospectively) and they wanted to inspect it regardless.
Peter wrote:
The Sony camera is far more aerodynamic than a Go-Pro.
But is it really so? The GoPro presents a surface of 7 * 5.5 cm – what about the Sony?
That CAA doc was posted here recently, somewhere… local copy
It’s very interesting, although it is all common sense really. Non-EASA aircraft only though
The GoPro presents a surface of 7 * 5.5 cm
The FDR-1000V frontal area is 24×51mm. That is the camera alone and some people fly with that (not in rain). In the waterproof housing it is a few mm more all around. Discussions with pilots using the Go-Pro suggest that the GP can easily suffer from a lack of rigidity, if the single mounting point is used.
Just saw that the GoPro 4 frontal area (silver & black, with housing) is 41×59mm. That’s nearly double compared to the FDR-1000V.
