Houjou Aimi

For MIG and Flux core welding, do you need a differently rated shade. We have a # 10, and don’t know how to tell when we could need a darker shade like a 12 for example. Somewhere we read about looking at a bare light bulb to see if you can see the outline of it as an indicator of needing a darker shade. We are just learning about welding and would like to know when an auto darkening system is better and how to pick a good one.