Motion blur comes from subject movement during the exposure, so you need to make the effective exposure very short.

Two main approaches:

1. fast shutter speed Use a camera that handles high ISO well, and a lens with a wide maximum aperture so you can let in more light. A faster shutter reduces blur, but raising ISO adds noise, and opening the aperture reduces depth of field.

2. flash This is how many classic night train photos were made. O. Winston Link is known for using large multi-flash setups; one example used dozens of flashbulbs triggered together. Flash can freeze motion because the flash burst is very brief, even if the ambient exposure is longer.

So the important attributes are:

• good high-ISO performance from the camera
• a lens with a wide aperture
• enough lighting power, often flash, if the subject is large or distant

For something as big as a train at night, lens speed alone is usually not enough; substantial lighting or multiple flashes are typically required.