If you're trying to re-create an old photo (for a then and now photo-pair), it's important to work out which angle it was taken from. If you're trying to reproduce the scene exactly then you might need to think about perspective - this is how the subject of the photo relates to it's surrounding, particularly the background.
Perspective is affected by the focal length of the lens you are using. If you can't change your lens, or you're restricted to taking the photo from one spot because there are roads or buildings in the way then there's nothing you can do about it. If you do have a choice, look at your old photo and try to decide what sort of lens it was taken with:
Wide-angle lenses can exaggerate perspective - they make objects in front of, or behind, the subject look further from the subject than they do in real life.
Telephoto lenses can compress the perspective and make objects in front of, or behind, the subject look closer to the subject than they do in real life.
If you compare the old photo with what you see then you can probably work out what sort of lens was used. If the photo looks pretty much like the scene you see with your eyes, then it was probably taken with a standard lens.
Some films and videos take advantage of this effect of changing perspective - if you move towards the subject and zoom-out at the same time, so that the subject remains the same size in the frame, it looks like the background stretches away behind them.
The pictures below show the effect of using lenses of different focal lengths. Pingu was in the same position throughout, so the distance to the houses in the background didn't change. As I changed to progressively "wider" lenses I moved closer to Pingu and tried to keep him the same size in each picture.
In these pictures the background is the thing to look at - while Pingu looks pretty much the same in each photo (but not exactly the same because it was windy and he kept blowing over!) - but the background is changing. This is because the focal length of the lens (i.e. the amount of zoom) is changing the perspective. Notice also that there is a greater depth of field with the shorter focal length (i.e. wide-angle) lenses, and that the sky gets bluer the higher up you look!
