I am getting ready to go on an outing with my family where we will be riding on an open air tram and there will be various wildlife that we get to see. I assume the wildlife will be at various different distances from me and my camera and it got me wondering how I could use my speed graphic in a quick way without having to focus. I thought it would be a lot of fun to have the speed graphic with me for this and everyone will probably think I am crazy which could be some fun within itself.

My first thought is that I just set the 150mm lens to infinity and then ensure the animals are far enough away to make sure they are sharp enough.

The only thing is that I am not sure how to go about figuring out how far the animals need to be away from me and my camera with the 150mm lens to be in focus.

Does anyone have a guideline that you can share that is simple and easy to understand without using complicated math and theories?

Any help is appreciated.

Larry