Now, one needs to know if the shortlisted vendor is really using the latest camera and lenses and other equipment, in tune with the times.
So, you need to be a little aware of the trends in the business now.
Many professional photographers use Canon cameras; they would probably be using a 5D Mark III or Mark IV models. Nikon and Fuji are also popular cameras with photographers.
Canon 5D Mark IV and Sony cameras are some of the popular ones that are used to cover wedding videos. Both Canon and Sony are equally good and the difference would be the default colour tones that the images are captured; again, the defaults may be tweaked to the cameramans preferences.
The reason people continue with the same brand once they are comfortable is that for each camera, the settings are different and there is a learning process. So, if a professional is comfortable using a brand, the change to another brand would mean a process of re-learning for the new brand.
But, usually, if the features that are offered are exceptionally good, they do willingly shift to the better make and models.
The cameramen usually come with an assistant cameraman or two, to help them with the changing of lenses. Some of these lenses are really heavy and the camera needs to be mounted on a monopod or tripod to get maximum control on the weapon.
The assistant cameraman usually has these kinds of lenses in his kitty.
Medium zoom lens (24-70mm)
Telephoto lens (70-200mm)
Wide angle lens
The cameraman sometimes has two cameras hanging from his expensive shoulder strap holding his cameras. Usually one of the cameras will have a prime lens and the other would probably have a medium zoom lens, so that he need not change lenses frequently and can concentrate on capturing images than worry about changing the cameras lens.
The assistant may also be hiding an audio recorder, which would be taken out to capture real time audio recording, which may be used in the videos for a powerful narration.
Apart from these, the camera team would be armed with lights, extra memory cards, light stands, spare batteries.
These cameras that the professionals use are very expensive and usually have a very high MTBF value. But still, some professionals always have a backup camera, just in case.