It depends on the employment contract and how you are being paid.
Every employment contract I have ever signed has included the job description I was being hired for and has also included "additional tasks as requested." Compensation has usually been hourly, but occasionally salary with no OT pay (the company owns me 24-hours a day, essentially).
In each case (salary and hourly), I have been asked to take photographs (construction/scouting purposes for domestic oil & gas exploration). It is an "additional task" which is accounted for under my employment contract, gets me out of the office, and I get paid for it as a normal part of my compensation agreement (maybe it is regular hourly pay, maybe OT pay, or maybe weekend work done under salary).
But, my employer MUST provide the tools I need to take those photographs: the camera equipment I will be using, a company truck and gas card, and a per diem (if I'm going to be on the road a while) for meals/hotels if required. Kilometre reimbursement and a company gas card are required if the use of my own truck is necessary due to a shortage of company trucks.
Note that I'll will use my own truck if required, but not my own camera equipment. There is no "standard" compensation for the use of camera equipment in my industry. Chainsaws, quads, trucks, GPS, and survey equipment? Yes. Cameras? No. In addition to the unknown compensation factors for camera equipment, the use of my own equipment could be used (by me) to try to muddy the copyright ownership waters if I was so inclined. Note: the copyright issue is the one I use to convince employers to invest in their own camera equipment . . . it has worked every time. Their employee, their equipment, their photos. The waters are pretty clear.
Don't do work that you aren't compensated for. No good will come of it. You might think that if you do you'll get "brownie points," but you won't. You might get a pat on the back, and then you'll be asked to do bunch more things without appropriate compensation: because you made it clear to them that you're a push-over who they can exploit. It won't make you more valuable to them. Everyone is replaceable. Be aware of what your employer can request of you based on your employment contract. Don't refuse to do things that your employer can request of you based on your employment contract (unless you have really legitimate safety concerns, or the like), and don't let your ego be your enemy (I've seen this more times than I can count when it comes to "additional tasks," it just gets people fired).
There may be some things that complicate the issue a bit for you. How would you be paid in this position? Is this a commission only position? What are your professional goals here? Would taking photos with your own gear help you sell more advertising spaces and better be able to reach your goals? Do you stand to realistically benefit from taking photos with your own gear at these events? Remember, "brownie points" are not a realistic benefit.
There are lots of things to think about and consider.