Hello fellow photographers! Im wondering if anyone more experienced in lighting could give me some input on this topic. I have been shooting for 15+ plus years, I have always preferred and enjoyed natural light, I have shot with strobes and speedlights when i was doing more media work and the people i was photographing were still. I have started focusing on children, newborns and family and for the most part i use the natural light in my home studio. I recently had a cakesmash session and right before the the clients arrived the lighting completely changed and the sun was just way too strong and shining in a weird position where i had my set up, so i rolled my roller blind down and pulled out my speedlight and put it in an umbrella, now my issue and inquiry here is, when i shoot with the speedlight my aperture needs to be at 1/160 other wise i get the black bottom bar, the subject is a 1 year old who doesn't stop moving, although i got enough good shots because i over shot, there were so many blurry images where his face wasn't sharp at all. My settings were 1/160, 2.2 and around 200 - 300 iso, my speedlight was on ETTL and on high speed. My question is, how do you get the image sharp shooting 1/160? Especially when the subject is always moving around. Does anyone have any lighting recommendations for photographing children?
If you're seeing motion blur with a speedlight, it's because your ambient light is too much. The speedlights flash duration will be much quicker than 1/160th and freeze motion on it's own. You need to let the speedlight expose your subject, not the ambient light. If that's done properly, you'll get motion freezing when shooting lower shutter speeds like 1/80th or even lower.
I almost always do manual flash power, and always always when using them off-camera so I can really dial in my exposure for the flashed subject and ambient light. I only use ETTL when shooting in lighting conditions that change frequently.
High speed sync on your speedlight should allow you to shoot faster than 1/160th provided your lights are properly communicating with your camera, but sounds like that's not the case, and it does affect power output, so you should turn it off since you aren't making use of it.