overexposure

Hello! I am a novice when it comes to film and photography, just having some fun. Recently, all my photos have been a bit disappointing, and I am looking for some advice! I am shooting on an Argus A-Four I found in a thrift shop, (and will probably get a new camera soon) and I am shooting on...

There may be an answer to this question somewhere else but I am a little confused. If I shoot Portra 400 35mm at 200 ISO instead of box speed, do I need to let the lab know to develop it differently? If so, what is the difference and why can’t the over exposure be achieved by developing the film...