I have gotten into event photography. I have a Canon 650d and Sigma Lens 18-250mm 1:3.5-6.3.

Is this setup okay for event photography? What seatings would you recommend for this equipment interms of ISO, SS and aperture.

I am also really confused about the aperture stuff. When I plug it the lens into my camera it allows me to select aperture of even f22. Is that wrong how does it work? Does the lens decide what aperture it will work on for example at 18mm it will use f3.5 and 250mm it will use f6.3? Or can I use f6.3 at 50mm?

My current seatings go about like this SS- 1/200 ISO- approx 400-800 using external flash too not sure if that makes any impact Aperture- f6.3

I was thinking isn’t it better to set ISO and Aperture on Auto and just have SS fixed?

At the same time clients want blue background group photos for normal photos and full clear background for cake cuttings & etc.

Please provide suggestions I am really confused about how it all works together.

Note- I do know the definition of these terms it’s just hard to understand how they work together.