I hope this isn't a daft question but if so please bear with me.
When considering a lens infamous for focus shift my understanding is that such a problem only occurs when focusing wide open and subsequently stopping down. Conversely, if one focuses at the desired aperture and adjust shutter speed for correct exposure then this issue is a non event. Am I correct in this assumption?
As an aside, is there any benefit in actually focusing wide open prior to stopping down?
I'm a bit naive on these points and would appreciate your advices.
Thank you in anticipation of any responses.
Apologies, should be in lens thread. Please move.