Barry Green's HVX book wrong on depth of field?

D

dcragoe

Member
Many cameramen are under the impression that you can reduce depth of field by simply backing up the camera and using a longer lens. A friend showed me the HVX book and it seems to spread this idea. I believe it's wrong. As an instructor at AFI told me, "there is no free lunch." Here's a quote from Independent Filmmaking by Lenny Lipton (1972)
"The perverse fact of the matter is that all lenses, no matter what
focal length, have the same depth of field for the same image size, with the
same f stop (for the same format). This means that if the filmmaker wishes
to film a subject so that it is the same image size with a long lens as for
a short lens, he will have to get close to the subject. Now remember, the
image formed by the lens in this example is the same size - it remains
constant. As the filmmaker approaches the subject to increase the image
size in the viewfinder, or on the film, if you like (or to maintain the same
magnification, if you prefer this terminology), depth of field will be
correspondingly altered so that the depth of the short lens and the long
lens will become the same."

Did Green make a mistake in the HVX book?

I have the DVX book and it is an excellent source of information. I appreciate Green's work, but I strongly disagree on this issue.
 
Might help if you added a page reference to Barry's book for the section you have issue with.
I just checked 'Depth of Field' in the index and it's got quite a few page references.
 
I don't have the book handy, but as I understand it there are three steps involved (of which you only mention two).

1. Move the subject as far from the background as you can
2. Zoom the camera to full telephoto and move it as far from the subject as you can while still framing the subject the way you wish.
3. Open the iris all the way.

And this will satisfy the problem as described by your quote as there is the added "change in f stop" by doing this.


(Hopefully I explained it right ... either way Barry will surely stop in and comment when he can)
 
Okay - I'm looking over the book (page 100) and it seems that Barry is saying the same thing you are...he's very careful to say that as you backup and increase focal length the depth of field will "appear" to be shallower. Which is absolutely true.

And then on page 104 he goes into a whole explanation about the effect of moving further from the subject and zooming in, with examples - and explains why they don't quite cancel eachother out.

In fact, at one point he even captilzes the word "APPEARANCE" in reference to the illusion of a shallower depth of field.
So, I'm not sure I'm following what your concern is.
 
Doug, what barry was trying to communicate is that, given the subject is identically represented in the frame with both a wide angle or telephoto lens, and the aperture is the same, the depth of field will be theoretically the same

BUT the tele lens will magnify a smaller portion of the background, emphasizing the fact that it's out of focus, causing the depth of field to appear shollower, and the bokeh to appear smoother and silkier.

When I want shallow DOF, I reach for my Zeiss 85 prime, get as close as I can, and open up the iris (compensating with ND filters of course)
 
Oh I see I didn't fully grasp the question. Right, the depth of field isn't actually changed, but the telephoto exaggerates the magnification of the background (when you apply the three steps) thus giving the illusion of the oft sought after DOF.
 
Larry R said:
Oh I see I didn't fully grasp the question. Right, the depth of field isn't actually changed, but the telephoto exaggerates the magnification of the background (when you apply the three steps) thus giving the illusion of the oft sought after DOF.
Click to expand...

Bingo.
And the book actually has a two page description explaining that in detail - together with example frames.

The more important question here, Larry, is why don't you have Barry's book handy?
:)
 
happy to be of service.


remember three things effect DOF

Aperature
CAmera to subject distance
focal length

Shallow depth of field example
105mm F2.8 2 three feet from subject

vs.

28mm f 5.6 10 feet from subject (DEEP DOF)
 
Luis Caffesse said:
The more important question here, Larry, is why don't you have Barry's book handy?
:)
Click to expand...

Well, the bigger sin is that I am actually not a DVX/HVX/HPX/HMC owner at all, the closest I've come is that my sister has the DVX, but she lives 2 hours away from me.

Besides, as you should well remember, part of the mod selection criteria is the ability to commit every thing BG every says to memory ... of course, the tricky part is being able to recollect any of it :grin:
 
Danielisnotadrummer said:
happy to be of service.


remember three things effect DOF

Aperature
CAmera to subject distance
focal length

Shallow depth of field example
105mm F2.8 2 three feet from subject

vs.

28mm f 5.6 10 feet from subject (DEEP DOF)
Click to expand...


We did this earlier this years for an interview series.

Worked well.
 
Curious if you saw the whole article in the book? I specifically demonstrated a side-by-side picture that shows exactly how the longer lens/backed-up situation does show the "effect" of a softer background, and explained that while the DOF is technically "the same", the simple fact of the matter is that the optical magnification of the background in the tele shot makes the APPEARANCE of shallower DOF unquestionably enhanced when backing up and zooming in. Here's the picture that shows the difference clearly:
DOF-Combined.jpg
 
Last edited:
Danielisnotadrummer said:
Doug, what barry was trying to communicate is that, given the subject is identically represented in the frame with both a wide angle or telephoto lens, and the aperture is the same, the depth of field will be theoretically the same

BUT the tele lens will magnify a smaller portion of the background, emphasizing the fact that it's out of focus, causing the depth of field to appear shollower, and the bokeh to appear smoother and silkier.

When I want shallow DOF, I reach for my Zeiss 85 prime, get as close as I can, and open up the iris (compensating with ND filters of course)
Click to expand...

Sticky!:beer:
 
Barry is extremely careful in his book to explain DoF both in theory (technically, it doesn't "change") and in practice (here's what to do in real life to get the effect you are looking for).

One great tip in Barry's book to achieve the appearance of shallow DoF is to go full wide with the lens, but bring the performer as close as reasonably possible. The focus will have to be so close that the b.g. goes soft even with a wide lens.

I had never thought of this technique before, and I was thrilled when I saw the result. The super-long-lens CU has its merits as a beauty shot, but you can lose almost all sense of place, so for drama I use it sparingly - mainly for very intense moments when the characters actually would be extremely focused on each other and forget about their environment.

But with the close-subject wide-angle technique you can direct the audience's attention with the focus and still not lose the environment. The effect is much closer to the normal-lens CUs often used in Hollywood dramas.

Thanks, Barry!
 
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