Can you shoot 400 ISO at night?
Yes on a tripod, where you can use a long exposure to make up the light. Handheld with a moving subject at night, 400 is usually far too low.
ISO 400 is a moderate setting. Whether it works at night has almost nothing to do with the number and everything to do with whether you can afford a long shutter speed.
**On a tripod, yes, easily.** With the camera fixed and the subject still, you can expose for seconds. A night street scene, architecture, a lit building or a light trail all shoot happily at ISO 400 with a multi second exposure, and you get cleaner files than pushing to 6400 to keep the shutter fast.
**Handheld with a moving subject, usually no.** A person walking at night needs a shutter fast enough to freeze them, perhaps 1/125. To reach that in low light at ISO 400 you would need an extremely fast lens and generous street lighting. Normally you need 3200 or higher.
So the real question is never the ISO on its own. It is whether the shutter speed you need is compatible with the light you have.
**What ISO actually costs.** Higher ISO adds noise, reduces dynamic range and desaturates colour slightly. Modern cameras handle 3200 far better than cameras from a decade ago, and a noisy sharp photograph beats a clean blurred one every time. Do not underexpose at low ISO to protect a number, because lifting a dark file in editing produces worse noise than shooting at the correct higher ISO would have.
## What this means for product photography
In a studio the question does not arise, and it is worth understanding why, because it explains most of how product settings work.
A product does not move and the camera is on a tripod, so there is never a reason to leave base ISO, usually 100. However dark the room, you solve it with a longer exposure rather than a higher ISO. That keeps noise out of exactly the fine label detail that a marketplace zoom magnifies.
If you find yourself raising ISO during a product shoot, the setting is not the problem. There is not enough light on the set, and the fix is more or better light, not a higher number.
The full starting point for product settings is in camera settings for product photography.