harry potter - Why Did Colin Creevey's Muggle Camera Work at Hogwarts?

Hermione says in Goblet of Fire:

‘All those substitutes for magic Muggles use – electricity, and computers and radar, and all those things – they all go haywire around Hogwarts, there’s too much magic in the air.'

_{Goblet of Fire - pages 475-476 - Bloomsbury - chapter 28, The Madness of Mr Crouch}

and in Chamber of Secrets Colin Creevey says this:

‘[A]nd a boy in my dormitory said if I develop the film in the right potion, the pictures’ll move.’ Colin drew a great shuddering breath of excitement and said, ‘It’s brilliant here, isn’t it?'

_{Chamber of Secrets - page 75 - Bloomsbury - chapter 6, Gilderoy Lockhart}

How is it that Colin Creevey's Muggle camera works properly at Hogwarts and on the Hogwarts grounds? Further, how is it that a magical potion could create moving pictures from Muggle film, which only takes one-framed (for lack of a better description) shots at a time?

I'm assuming Colin's camera is not digital, as this is 1991 (first expensive DSLRs appeared in 1991), plus Colin, obviously, references film.

Answer

The Harry Potter wikia has an answer (it "runs off of the magical atmosphere"), but the reference is the entire second book.

Other than that, I think @Zoe is correct - all the examples given in Goblet of Fire require electricity, while old-fashioned cameras didn't use it for anything other than the flash. Nothing more than a spark is needed for the film and a flash for the bulb, so even if it goes haywire there's not much that can go wrong.

As for how they can move - he didn't say what they'd be doing when they moved. I think, although I'm not certain, that it was covered somewhere else on another HP question - wizarding photographs are developed in a special potion that makes them come to life, and Colin could have been referencing that. So they wouldn't necessarily be doing the exact same thing they were doing when the picture was taken, unless that was part of the magic (perhaps based on the caster's memory?).