What's the ideal distance to subject when using the 64" AB PLM for head shots and for portraits? I'm using the silver one and also using a 45" white bounce umbrella for fill with AB 800's. Camera settings at 1/250, ISO 200, @ f8.
If your 64 inch PLM has a flash located right to focus the reflector, the main light will be a beam about the size of the modifier, which is around 60 inches. It does not spread too fast, so the distance does not matter very much. You likely would want to keep it back a little, like 5 feet or so, just so it is not crowding the model. The angle of the PLM on the subject is the main factor in the lighting for that modifier. If you want strong down angle, your ceiling may limit how high you can put the PLM, and thus it may end up close to the subject. Your fill lighting does have more spread, so its distance causes more changes in exposure.
If you have one of the diffusers for your PLM, and want to use that, then the distance matters more, and you likely will want to bring it in fairly close so that it is just outside of the frame. A diffuser on a PLM changes the look of the light it gives, and it is well worth having one unless you are all set with other softboxes.
Roland thank you very much for your response. I do in fact have the diffuser. I forgot to add that in the OP. FOr the most part when using the PLM with the diffuser, I've been setting it about 5-7 feet away from my subject. I just started using it, and I'm not too familiar with it. I am definitely going to try your suggestions the next time I use it.