The choice of camera for bulb photography is important but not too difficult.
I consider there is only one essential criteria for choosing a camera: you must be able to leave the lens open for as long as you want.
This sounds really obvious but, with modern and cheaper cameras this is not necessarily as easy to achieve as you may think.
If you are buying a camera on a budget - like I always seem to be doing it - then a castoff of hand me down or second hand camera may not only fit the bill - it could be better than a newer more modern one.
I prefer a mechanical (not electrical) shutter release - often that means an older camera. If the lens is kept open by an electronic mechanism it is not always clear what will happen when the battery runs out!
One of the reasons why I bought an Olympus OM-1 was because I read in a review that about the only thing you needed the battery for was the light meter, and the light meter in an OM-1 is used as a guide only - it is not part of the shutter mechanism. If you are planning a long trip - especially away from civilisation (eg. on the high seas) - then you can live without a battery if it only means you have no light meter!
The next near essential feature in a camera is a cable release. This allows you to open and close the shutter without touching the camera. I prefer to have a manual cable release (again a feature of the OM-1) for the same reasons as mentioned above - it's not clear what happens when the battery fails.
A checklist for your long exposure camera. You should get a camera with at least the following features:
- the ability to leave the lens open for as long as you like
- shutter cable release
- should be able to mount on a tripod
I have used the following cameras regularly and have provided some details about each: