Thanks to those who recommended a couple of Brian Peterson’s books to me. I have found them very interesting.
In Learning to See Creatively, Brian Peterson instructs that one will obtain more background and foreground blur (bokeh?) outside the focal plane by using (in his example) a zoom when set at 135mm verses the same zoom when set at 60mm, at the same aperture and the same field of view (p. 41). (Obviously, the depth of field narrows the more you zoom, but he is talking about maintaining exactly the same field of view, backing up from the focal plane as you zoom in).
As I play with depth of field calculators, it appears that the depth of field at a particular aperture is almost exactly the same when shooting wide and up close, or zoomed in and far away, so long as the field of view is the same.
This seems to imply that one could stop down a little and get the same bokeh but with a deeper depth of field, simply by using longer focal lengths and backing up from the focal plane. (I imagine some of it has to do with lens construction, but Brian Peterson is talking about using the same zoom lens set to different focal lengths).
So my question is, how much could I stop down and get the same bokeh when using longer focal lengths at the same field of view?
For example, going from a EF 50mm f/1.4 USM to a EF 85mm f/1.8 USM (on a 1.6x crop sensor camera). Could I get the same bokeh with the 85mm at f/2 as the 50mm at f/1.4, while increasing the DOF slightly (at the same FOV)?
How about going from an EF 50mm f/1.4 USM to a EF 24-105mm f/4L IS USM @ 100mm (50mm equivalent:160mm)?
BTW, I’m not so interested in the “quality” of the bokeh. I just want the background and foreground to look out of focus.
Thanks in advance. I'll be watching this thread, but may not have time to reply for a couple of days.
In Learning to See Creatively, Brian Peterson instructs that one will obtain more background and foreground blur (bokeh?) outside the focal plane by using (in his example) a zoom when set at 135mm verses the same zoom when set at 60mm, at the same aperture and the same field of view (p. 41). (Obviously, the depth of field narrows the more you zoom, but he is talking about maintaining exactly the same field of view, backing up from the focal plane as you zoom in).
As I play with depth of field calculators, it appears that the depth of field at a particular aperture is almost exactly the same when shooting wide and up close, or zoomed in and far away, so long as the field of view is the same.
This seems to imply that one could stop down a little and get the same bokeh but with a deeper depth of field, simply by using longer focal lengths and backing up from the focal plane. (I imagine some of it has to do with lens construction, but Brian Peterson is talking about using the same zoom lens set to different focal lengths).
So my question is, how much could I stop down and get the same bokeh when using longer focal lengths at the same field of view?
For example, going from a EF 50mm f/1.4 USM to a EF 85mm f/1.8 USM (on a 1.6x crop sensor camera). Could I get the same bokeh with the 85mm at f/2 as the 50mm at f/1.4, while increasing the DOF slightly (at the same FOV)?
How about going from an EF 50mm f/1.4 USM to a EF 24-105mm f/4L IS USM @ 100mm (50mm equivalent:160mm)?
BTW, I’m not so interested in the “quality” of the bokeh. I just want the background and foreground to look out of focus.
Thanks in advance. I'll be watching this thread, but may not have time to reply for a couple of days.