Does anyone know the longest I can keep the shutter open and still end up with a fairly in focus moon? I'd like to get a photo of the moon just after it rises over the city skyline but am thinking my typical 30 sec shots will result in a big white blur instead of something that looks like a moon. So my idea is to stitch together photos shot at 30 sec with the one with the moon at a faster speed/higher ISO, but not sure what that speed has to be. It doesn't have to be super crisp or anything, but I would like it not to have trails.
TIA
TIA