My 2 cents. **I.** If you want "**action photos**" I would recommend the smallest focal length. (the 35mm) This is because a manual lens is harder to maintain in focus, and the shorter focal length will give you a bit more room. **II.** If you want "**portrait**", and they can pose for you, try the widest aperture (the f1.4) **III.** For some "**documentary style**", (the kids sitting watching some other kids, and you taking the photos a bit far away) use the longest focal length, (135mm) at the widest aperture. --- **IV.** Always keep the **Sunny 16 rule** in your mind. (Or prepare a cheat sheet) https://en.wikipedia.org/wiki/Sunny_16_rule **V.** If you want to freeze the action, try an ISO 400 film and adjust the exposure accordingly.