 Now, the whole thing about minimum exposure time is that this stuff is ionizing radiation. Especially when you start talking about very hard x-rays which have a higher level of energy, you want to spend the minimum amount of time around them as possible. Judging by the haircuts here, I judge this, what, late 70s, early 80s anyway, it's a dental x-ray. The dentist leaves the room and that fella that's getting the dental x-ray has a big lead apron on to try and block the radiation so that it doesn't need to go or it doesn't need to be. And when they take the x-ray, they don't just leave the tube blasting for ages and ages and ages as much as that would create a very sharp image. They just do enough to get the image they need and then they stop. Because it being ionizing radiation, you just need to do what you need to do to get the image that you require and no further. This is something I really enjoy. This is a 1930s, 1950, I think you all phased out, x-ray shoe fitting device. So you look through, your mum looks through and the salesman looks through and you stick your feet in this hole and an x-ray tube sends all these x-rays up and then there's like a fluoroscopy kind of thing that turns it into visible light. So you can see your bones of your feet inside the shoe whilst all these x-rays are blasting up through your head. And a bit earlier than that was the use of x-ray hair removal devices where you would put your face up against an x-ray tube which would release those x-rays and it would kill off the hair follicle cells, the tricose system. Yes, there are a lot of things in the past which are quite hair-raising.