Hello, I wonder if anyone can help me as I am new to film photography. I am using a Canon A1 with a 35-70mm lens and have just bought some Kodak Portra 400. I will be shooting indoors in a well lit room with neon lights. I have set my ISO to 400 to match the film but does anyone know what the best shutter speed I should be using? The only options I have on my camera are 1000, 500, 250, 125, 60, 30, 15, 8, 4 etc. I was using Portra 160 film before with shutter speeds between 250 on a sunny day and 30 indoors. The ones at 250 in daylight looked really nice, however the indoor shots with shutter speed between 125 and 30 came out really dark and grainy, it was pretty disappointing. I thought if I got a faster film it might help?