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Example of DOF in head shots

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Julia Borg said:
Julia Borg said:
Cut the rhetoric, show us your studio work, may be we all could
learn from you.
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I do not teach practical photography for free :)
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Ok, the word learn got you going, I don't need to learn photography from you, I am qualified enough in this area, but it was put in a polite way.

Nevertheless, I recognise your expertise in software and digital.

I would still love to see your studio work, if possible.

If it is not possible, it's ok

We'll still have to agree to disagree on the DOF & lens relationship.

Ok Julia, no hard feelings, I don't harbour negative feelings

WE can depart on that!
 
It all depends on the distance + the lens in mm and how big the thing is that you photograph (head in this case, maybe an orange next day or an fly).

There is no "one setting fits all", that is why it is recommended to use the DOF preview button on your camera.

--
Rickard Hansson
Sweden
 
Absolutely. However, this thread may be read by people using P&S for portraiture of those near and dear, and by those who might extrapolate this DoF rule to other subjects. So I see nothing wrong in specifying the limits within which this rule is true.
Julia Borg said:
Julia Borg said:
until you come close to hyperfocal distance
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the thread is about portraiture, right?

--
Julia
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--
Cheers,
Stas.
 
Diffraction can become a problem. I figured at f178, I had enough DOF, but that old devil diffraction reared its ugly head.



Of course, since there was no lens used, without diffraction there'd have been no image at all.

50mm focal length pinhole, F178. Happy Pinhole Day, Sunday April 29.
 
There's a reason why a lot of the hot commercial portrait shooters right now are in love with doing portraits with a 300mm lens. (as of a year ago, it was Seth Resnick's portrait lens of choice.) No, it's not because they are afraid of getting to close to the CEO. It's because they can do a tight head shot, with freakishly shallow DOF that will soften the facial imperfections and give nice crispy eyes, and it won't matter what's in the background because you won't see anything other than blur, and the CEO's nose won't look monumental even if it is. (ah yes, that other thing people here like to argue about, perspective vs lens focal length...)

If you buy completely into the purely quantitative viewpoint, then the only reason to change lenses is because the room is small our the outdoors is big, or because you're too lazy to walk. But nobody shoots portraits with a 10mm lens (unless they're hostile to their subject, or trying to be funny). And many of the better known landscape shooters advise you to hike away from your subject and use your 200mm lens instead of your wide angle. Better subject isolation, compression... and yup, it's not the lens that does it, but it's the lens that allows you to be far enough away for it to happen.

Some people believe what they calculate. Some only believe what they see.
bob elkind said:
It's important to understand theory upon which practical
considerations are based. On the other hand, Julia, you are
potentially misleading and confusing the readers with your
(somewhat) esoteric tutorial.

Pandering to the masses, I post the following:

assume D200, f/4 --
1. 50mm focal length, @10 foot distance, DOF is 2 feet
2. 200mm focal length, @40 foot distance, DOF is ~ 2 feet
3. 200mm focal length, @10 foot distance, DOF is 0.1 feet

If you are photographing the same subject in all 3 examples. the
composition of #1 and #2 will be roughly the same. #2 uses 4x the
focal length used in #1, and has the same DOF as #1, at 4x the
distance used in #1.

The comparison we all are used to making (except, perhaps, Julia)
is between #1 and #3. At the same distance from focal plane to
subject (and same camera, same sensor, same aperture setting, same
phase of the moon), the longer focal length lens results in a much
narrower DOF than the shorter focal length lens.

Julia, you are the university professor trying your darndest to
give your students a fundamental understanding of the principles of
light, physics, optics, photons, etc. Even though most of us
operate with a vocational school approach to photography, we all
benefit from being gob-smacked with fundamentals once in a while...
we need it, even though we don't always think in such fundamental
terms when we're "working".
  • Bob Elkind
Family,in/outdoor sports, landscape, wildlife
photo galleries at http://eteam.zenfolio.com
my relationship with my camera is strictly photonic
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Alan,

the example you gave with the 200 and 28 mm is a test I had to do at photo school. It's meant to show that the actual image recorded (perspective) is exactly the same with both lenses.

As the wide angle has a much larger field of view (FOV) you see more of the world on the picture and you see the strongly converging lines of nearby buildings etc. The telelens shows the buildings far away flatly and pasted together. It seems that both lense give you a different perspective, but when you crop out the center piece of the wide angle shot you can see that that portion is exactly the same as the full 200mm shot, only more grainy because of the enlargement.

Many people think changing a lens changes the perspective. After one does this test it's clear that the perspective stays the same no matter what lens is mounted. Changing lenses or zooming is basically the same as cropping the photo in Photoshop (although in the latter case the quality gets lower).

Because you change the reproduction ratio when you change the lenses in this test, the DOF is different.
Alan Brown said:
perhaps it is an excuse but I don't find it easy to assimilate
(Borg?) 'almost' one word answers... in threads

Hope this does not develop in to another thread, inside this one.

:)
bob elkind said:
Allan, Julia's correct, but your example didn't match her
assertions or her example, so even if you were right (which needs a
second look), the example you gave doesn't (and won't) help confirm
Julia's main point.
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--
Quote: If you think education is expensive, try ignorance.

Have fun :)
Sooty
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--
Philip

 
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