Comments on: 3 things that affect depth of field http://photonaturalist.net/3-things-that-affect-depth-of-field/ tips and tutorials for digital nature photography Thu, 09 Sep 2010 03:25:32 +0000 http://wordpress.org/?v=2.9.2 hourly 1 By: Jean-Christophe http://photonaturalist.net/3-things-that-affect-depth-of-field/comment-page-1/#comment-12479 Jean-Christophe Sat, 13 Mar 2010 15:27:12 +0000 http://photonaturalist.net/?p=2555#comment-12479 hi, As the post you refer to puts it, "All this technical stuff is fine and dandy, but how does it translate to real world photography? " Lets take a real-world example such as an outdoor portrait. Supposing I have a constant aperture f2.8, 50-200mm zoom set to a given f-number, I would obtain the same subject-composition at 10 feet with lens at 50mm than at 40 feet with lens at 200mm ( _correct me and read no further if I am wrong here_ ), and according to the DoF calculator, roughly the same DoF. I don't know if this is exact or approximate (the maths seem a bit complicated), and I have not tried it out (I don't own such a zoom). Other elements should not be overlooked too : background composition would of course be very different, and the bokeh (the blurry effect) might have a different quality at 50mm than at 200mm. So if this is correct, for a chosen composition, the only factor to consider regarding DoF is the lens' aperture. (Winston : yes DoF is also dependent on sensor size, but that is not a factor we can usually control) -JChris hi,
As the post you refer to puts it, “All this technical stuff is fine and dandy, but how does it translate to real world photography? ”
Lets take a real-world example such as an outdoor portrait. Supposing I have a constant aperture f2.8, 50-200mm zoom set to a given f-number, I would obtain the same subject-composition at 10 feet with lens at 50mm than at 40 feet with lens at 200mm ( _correct me and read no further if I am wrong here_ ), and according to the DoF calculator, roughly the same DoF.
I don’t know if this is exact or approximate (the maths seem a bit complicated), and I have not tried it out (I don’t own such a zoom). Other elements should not be overlooked too : background composition would of course be very different, and the bokeh (the blurry effect) might have a different quality at 50mm than at 200mm.

So if this is correct, for a chosen composition, the only factor to consider regarding DoF is the lens’ aperture. (Winston : yes DoF is also dependent on sensor size, but that is not a factor we can usually control)

-JChris

]]> By: Winston Mitchell http://photonaturalist.net/3-things-that-affect-depth-of-field/comment-page-1/#comment-12044 Winston Mitchell Thu, 11 Mar 2010 13:49:33 +0000 http://photonaturalist.net/?p=2555#comment-12044 .4 Sensor size? .4 Sensor size?

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