Depends
on how crisp the negative is!
If it is razor sharp there is no reason why you cannot enlarge it to its
maximum. A thirty-five millimeter negative should be able to produce a 24 x 30
centimeter print with ease and in exceptional cases 50 x 60 cm. To check if the
negative is of a good enough quality, enlarge part of the frame to 18 x 24
centimeters, if it looks a bit grainy the chances are that when the whole
negative is enlarged to 50 x 60 cm and viewed from a meter away it will look
good.
When
enlarging to larger sizes you need to take into account the distance that
people will see the picture from. Large photos are rarely viewed up close.
