Possible Duplicate:
How much distance should one move so that a shot that can be framed at xx mm be framed at yy mm?

I think the question is clear but I will provide an example.

To fill the whole frame with a subject using 60mm lens I have to be X meters from it. With 35mm lens I have to be Y meters from it. It's obvious that X > Y but how to calculate the actual distance (let's say that with 60mm lens, the distance is 1 meter)?

  • Isn't it just simply y = x*(35/60)? Not sure about this, hence not posting this as an answer. – Saaru Lindestøkke Jan 14 '13 at 16:28
  • @BartArondson This equation occured to me too but I haven't found any proof that it's correct so I rather asked here... – user219882 Jan 14 '13 at 16:33

Pretty sure this is an exact duplicate, but yes object size is directly proportional to focal length so the answer is x = (60/35) * y

  • Thanks... I'm sorry for the duplicate question, I haven't found the original one when searching... – user219882 Jan 14 '13 at 17:54

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