Here is one of the areas where I am not super comfortable with mirrorless cameras. This is just my opinion and not fact. Remember it is only my opinion.
If you are wanting to shoot fast pitch, and you are wanting to stop action, and you need a long lens to get there, nothing beats mid-level to upper-end pro level DSLRs…for example the Nikon D700 or D800 will work and allow you to shoot video on top of that too. They are terrific. The Canon 5D series is also going to be perfect for it.
However, if these cameras are just out of your budget…can you really take a GH3 with a high ISO and shoot fast pitch stop action shots? Maybe you could, but I would not get the picture that I wanted right now from a mirrorless camera or lens…maybe someday very soon. The fact is, I would just not be happy with it.
Be sure to watch the whole video for my full answer on this great question.
Will Crockett, commercial hybrid photographer, photo technology developer, and webTV personality is focused on learning how to master hybrid imaging. The skillful blend of photo+video+audio is clearly the future of photography, but how do we shoot and shape and share and sell these hybrid "eProducts"? Dunno, but with Will Crockett as the technical genius and unstoppable force behind this transition from shooting still photos into creating pictures with depth and dimension we will surely figure it out! : )
Will is an open, honest, bright guy that shares what he learns here on this website about hybrid, eProducts, mirrorless cameras, and all the wonderful software tools that allow us to make better, smarter images for share or the sell.
For years, non-pro photographers and pros alike have seen Will's videos, gone to his fun live events, and learned how to be a smarter photographer.
Take a look at Will's current (and classic) images at willcrockett.pro, his consulting work for clients big and small at CrockettCo.com, and the great info on hybrid eProducts and mirrorless cameras on hybridphoto.pro, and of course his premium videos at thephotochannel.pro.
Will is credited with the construction of the Lumix Luminary talent team, and the Fujifilm Elite Talent team, and is our "coach" of the Hybrid Heroes.