What is the length of focus with a 50mm lens?

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Filmkid2003

Well-known member
Hey everyone, I just bought a 50mm Nikon Nikor lens to go on a 35mm adapter and I am wondering what the length of focus is on a 50mm lens. By that, I mean, how many inches or feet will a subject stay in focus when moving around? Is the length of focus very small and the subject will go out of focus with the slightest move forward or backward or is there a good amount of room for the subject to move forward or backward without going out of focus? Thanks.
 
Nick, you are the man! Thank you so much! That website is exactly what I needed. The people on this forum are awesome! So, it looks like with a 50mm lens, the farther I am from the subject and the higher the f-stop, the longer the focal length I'll have. Is that correct? It also seems like the lower the focal length of the lens (say a 28mm lens compared to a 50mm) the larger the area that will be in focus? I'm still trying to learn what different lenses do.
 
The shorter the focal length, the deeper the depth of field. (Depth of Field or DOF refers to the amount of area that's in focus, in terms of distance from the lens -- so the less that's actually in focus, the narrower the depth of field).

To get shallow DOF, you would want to do any or all of these:
1) Get closer
2) Use a more telephoto lens
3) Open up the iris more (f/1.4 = very shallow, f/16 = very deep)

For deeper DOF, you would do the opposite:
1) Move further away
2) use a more wide-angle lens
3) stop down the iris (f/16 = very deep DOF, f/1.4 = very shallow)
 
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