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Old January 16th, 2009, 10:46 AM   #46
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Quote:
Originally Posted by Simon Wyndham View Post
I agree, we definitely need more people on two wheeled gyroscopically balanced transports in videos.
That and a steadicam - nice combination!!
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Old January 16th, 2009, 10:47 AM   #47
 
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I dislike pointilism. Therefore, all very fine paintbrushes should be thrown into the trash.

Who's to be the definitive judge of what's artistic and what isn't? Beauty is in the eye of...blahh...blah...blah. It seems very short sighted and closed minded to issue such blanket assassinations of technique.


And this is a pointless discussion.
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Old January 16th, 2009, 11:02 AM   #48
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Originally Posted by Simon Wyndham View Post
The camera cannot achieve the same sort of shallow depth of field, so there is no need to fight it. You can certainly get a good effect when set up correctly, but to zoom into every shot just to get something OOF is silly.
Simon,

I could not agree with this more. Completely agree with your points about the overuse of Shallow DOF and the misconception that it is "cinematic" just because the DOF is shallow.

That said, there have been a few times, outdoors is what comes to mind, where I really needed to minimize the DOF for aesthetic purposes. The background just looked better when you couldn't see the detail - wasn't an ideal background, but when out of focus it worked with the composition. I was using an HD100 at the time. FOR THAT SHOT I was able to mitigate the issue that shooting digital inherently has by zooming. With the EX1/3, it's even easier.

I certainly agree that to set up this way all of the time is at least arduous if not silly - that would feel like fighting with the camera. However, operators should not feel that they are doing something wrong just because they opted, in a shot, to decrease DOF for an effect.

If one is trying to gain a 35mm look or film adapter look in the EX cams, one won't be pleased. Conversely, compared to 1/3" cams, this camera naturally has a shallower DOF so the techniques for getting more separation from the background that have been used on 1/3" cams should work a little better with the EX cams.
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Old January 16th, 2009, 11:13 AM   #49
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Good points, Ted... and it should be clearly understood that moving the camera back and zooming in will indeed decrease the apparent depth of field (it doesn't matter whether this is an "illusion" or not -- strictly speaking, *everything* you see on a television screen is an illusion, electronically derived -- all that matters is whether or not the background is out of focus, and the zoom-in technique, while only a work-around, definitely creates this effect... as we've all learned in Photography 101).

See The Ultimate Depth-of-Field Skinny by Jeff Donald for more info.
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Old January 16th, 2009, 11:32 AM   #50
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Then I propose new vocabulary.

Instead of Depth of Field, perhaps:

DoAS - Depth of Apparent Softness

DoANS - Depth of Apparent Non-Sharpness

C'mon guys, DoF is DoF and I'm sorry Simon, but the images I posted clearly show differing DoF which is no "illusion".

Also, my apologies for the thread hijack.
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Old January 16th, 2009, 11:43 AM   #51
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Wow my post started a pretty heavy technical discussion on DOF, haha. Anyhow, thanks to everyone for their input, definately learned a lot. I guess I'll make a thread specifically in a more genral section of the forum abiout people who have used the Redrock micro adapter.
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Old January 16th, 2009, 11:52 AM   #52
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Hi Pasha, instead of starting a new thread about those adapters, please join one that's already in progress... they are a popular topic of discussion around here and we already have more than enough ongoing discussions about them.

There is nothing "illusive" about different techniques of achieving shallow depth of field... either the background is in focus, or it isn't... moving the camera back and zooming in certainly is one way to do it. Maybe not the best, as Jeff Donald explains in the DVi article linked above, but definitely the easiest and least expensive method.
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Old January 16th, 2009, 12:28 PM   #53
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Quote:
Originally Posted by Bill Ravens View Post
I dislike pointilism. Therefore, all very fine paintbrushes should be thrown into the trash.

Who's to be the definitive judge of what's artistic and what isn't? Beauty is in the eye of...blahh...blah...blah. It seems very short sighted and closed minded to issue such blanket assassinations of technique.


And this is a pointless discussion.
Sorry... I'll stick to hard facts in the future.
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Old January 16th, 2009, 01:05 PM   #54
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Quote:
It seems very short sighted and closed minded to issue such blanket assassinations of technique.
Ahh but it is in fact a reverse. Striving for short depth of field when the camera is not capable of it instead of exploiting what the camera can do out of the box. So the saying goes that art is born of restriction and dies of freedom. And that is the problem, that the overuse of a technique is killing it. Anyone seen a Bullet Time effect in a movie recently?

Quote:
C'mon guys, DoF is DoF and I'm sorry Simon, but the images I posted clearly show differing DoF which is no "illusion".
You have missed the point. The DOF wasn't different, it was just more apparent. Its the same as if you showed, say some ever so slightly out of focus HD video on a small display. Because it was a small display (such as a viewfinder) it looks in focus. Now you blow that same footage up onto a big screen and it looks really soft because now you can see the error in the focussing. And that is the same effect you are getting when you zoom in.

What looks in focus in a wide angle actually isn't. But you cannot see just how out of focus it is until you zoom in. This is precisely the reason why the zoom in, focus, then zoom out method is used, because it ensures focus even though you may not be able to see it in a small viewfinder.

Quote:
and it should be clearly understood that moving the camera back and zooming in will indeed decrease the apparent depth of field
Yes, the key thing there is the word 'apparent'. And I agree with you Chris, it doesn't matter whether it is an illusion or not, whatever gets the job done. However it should be corrected that shallow depth of field is not achieved by the act of zooming in. You could for example, on a small chip camera, zoom in at f8 and everything would still be in focus.

So to be correct when we talk about these things the advice should be:
1. Open your iris wide open to create a shallow depth of field.
2. Zoom in to increase the visual differential between the subject and background that has been caused by that shallow depth of field.

Otherwise many people get caught in the trap of suggesting zooming in as a way to create shallow DOF when it is mainly the iris setting that allows it to happen.

Quote:
The background just looked better when you couldn't see the detail - wasn't an ideal background, but when out of focus it worked with the composition.
Oh I agree fully. You need to use these techniques in a motivated way. But a lot of people use them in an overly distracting way, for example close ups of peoples faces with 35mm adaptors where one eye is totally out of focus from the other. Now this may work in an artistic sense depending on the video, I don't dispute that. I've seen some amazing videos, particularly the wedding videos by a company called Stillmotion that use this. But many people are using the 35mm adaptors and seemingly leaving the lenses jammed on f1.7!
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Old January 16th, 2009, 02:24 PM   #55
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Originally Posted by Pasha Hanover View Post
That brings some hope back to this adapter, haha. So we have one thumbs up and one thumbs down. Anyone else have comments about the Redrock micro?
The RedRock Micro M2 doesn't work well on an EX1, at least for me. I had major problems with side (border on left and right) softness, and apparently, the limitation is the achromat itself. I even bought the hardware to hardmount to adapter to the EX1 threads so that it wouldn't drift as I moved the rig around. I suppose you could find another achromat with a larger diameter, but there is more to that selection that one would imagine.

Also, the super shallow DOF that you seek is a problem with 35mm lenses. All of the Nikon lenses that open up to f/2 or wider are very soft across the frame at wide apertures and display horrific purple fringing. f/2.8 is where even the best Nikon f/1.4 lenses start to behave.

There is the potential extra DOF available with the Nikon 105/135mm f/2 DC (Defocus control), but it's an extra burden.
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Old January 16th, 2009, 05:47 PM   #56
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Originally Posted by Chris Hurd View Post
...it should be clearly understood that moving the camera back and zooming in will indeed decrease the apparent depth of field (it doesn't matter whether this is an "illusion" or not [...] -- all that matters is whether or not the background is out of focus, and the zoom-in technique, while only a work-around, definitely creates this effect... as we've all learned in Photography 101).
I disagree. As I see it, the issue here and elsewhere is the confusion between background blur and DOF. They are not the same. There are several methods for increasing background blur. The two which have been the subject of this thread are: magnification and DOF.

The magnification method, or "back-up-zoom-in" technique, has these effects:
  • Same amount of the subject is in focus.
  • Perspective is altered drastically (and often detrimentally).
  • Composition of background is altered drastically.
  • Background blur is larger due to magnification.

The DOF method, e.g. a wider f-number, has these effects:
  • Less of the subject is in focus.
  • Same perspective.
  • Same composition of the background.
  • Background blur is larger due to being more out of focus.

Everything about them is different. Even the one thing they have similar, background blur, is different: blur caused by DOF looks different from (and better than) blur caused by magnification. The flattening/compression of perspective takes away from the perception of distance ("3D" look). Loss of background removes the subject from their environment, whereas DOF allows the background to contribute to the image, even if it's blurred.

Despite the fact that these two methods are different in every way, 99% of people talk as if they do the same thing. Even film school books get this wrong, e.g. Cinematography: 3rd ed., page 24. (That was one area which David Mullen didn't edit; he's aware of the difference.) It would be better if this myth were squashed out, at least here on dvinfo.net.

Using magnification (back-up-zoom-in) is a perfectly viable way to achieve greater background blur, and in many circumstances, it's the only method to increase background blur, especially with small-sensor cameras.

Using DOF is also a perfectly viable way to achieve greater background blur, if the camera/lens is capable of it. Sometimes it's an undesirable method, for example if it causes important parts of the subject (e.g. one eye) to go out of focus. That's one reason why magnification (back-up-zoom-in) is used on 35mm films: it magnifies background blur without making parts of the subject more blurry. In other words: DOF stays the same. So even if you could use DOF, another method, like magnification, might be better.

In addition to understanding that DOF and magnification are two very different methods of increasing background blur, we should also know their differences and trade-offs. Right now, the DOF is too expensive for many people because large sensors are too expensive with today's technology. Cameras like RED ONE and Scarlet are changing that, but we should still know the pros and cons of each method.

Also, it should be said that there are a variety of ways to make DOF thinner for a given subject:
  • Wider f-stop.
  • Same f-stop, but larger sensor and matching lens (same AOV).
  • Zoom in without moving.
  • Move in without zooming.

Note that "back-up-zoom-in" is not one of those methods. Also note that the last two methods cause a change in composition (perspective, background, field of view). The first two methods cause the DOF to get thinner without affecting the composition.

Again, there a many reasons why it's important to distinguish the difference between blur-from-DOF and blur-from-magnification.

The biggest, I think, is perspective. Many people do not appreciate the vital importance of perspective in their composition. To downplay the difference between DOF and back-up-zoom-in is to say that perspective is not important. But it is vital. One may compromise perspective to gain background blur, but the image suffers as a result. Perspective is also the reason that "zoom with your feet" is bad advice: the perspective must be chosen that best conveys the purpose of the image, not whatever is forced on you by the focal length.

For example, say the subject is a headshot, and at f/5.6, the entire face is in focus, including both eyes, ear, and nose. But you decide the background blur is not diffuse enough. You open up to f/2.0, and the change in DOF causes the background to become much more blurry and diffuse, just as desired. Unfortunately, it also causes the subject to have thinner DOF: now only one eye is in focus, the other eye is slightly blurry, and the ears and nose are really out of focus.

At that point, you switch back to f/5.6, but increase magnification by backing up and zooming in (for the same field of view). Now much of the background is gone from the image, which could be either good or bad. The background is also much blurrier, because the slight blur was magnified more. And, most importantly, perspective is now much flatter. The subject takes on a slightly more "2D cutout" look instead of 3D, and the background seems much closer than it really is. BUT: the good things are that the face is completely in focus, and the background is blurred nicely. Given how often this technique is used in Hollywood and on TV, you would be in good company to use it. (I like it too, but I enjoy truly thin DOF more.)

Here's a reverse example. Let's say you're shooting a head-and-shoulders shot with a Canon 5D2 and a 200mm super telephoto lens at f/2.0. You want the ears and nose in focus, but they're just not inside the DOF. So you do the opposite of "back-up-zoom-in": you zoom out to a shorter 135mm telephoto lens, still at f/2.0, and move closer to compensate. But the DOF is still the same; the eyes and ears are still out of focus. So you try 85mm f/2.0, 50mm f/2.0, 35mm f/2.0, 28mm f/2.0, and even a 24mm f/2.0. Even with the super wide angle 24mm f/2.0, the ears and nose are still just not in focus. The DOF is the same, all that changed was perspective, background, and background blur. To get them in focus, you have to change something that actually changes DOF, not background blur.

Quote:
Originally Posted by Chris Hurd View Post
...it doesn't matter whether this is an "illusion" or not...
It's not an illusion. Increasing background blur through the use of mangification (back-up-zoom-in) is reality. It may be a different blur than the background blur caused by DOF, but it's still blur. As Simon said, longer focal lengths increase magnification of the background, so even the tiniest bit of blur becomes larger in relation to the subject. If there is no blur (e.g. at the hyperfocal distance), then the magnification method doesn't work. Also, there are many subjects where it's hard to use that method (e.g. cramped rooms, wildlife, the moon, etc.) because it's impossible to backup or you're already using the longest lens you can afford.

A few quick quotes if you don't mind:

Quote:
Originally Posted by Peter Wright View Post
You can reduce depth of field on practically any camera, by moving the camera away and zooming back in.
That usually increases background blur, but it does not affect depth of field.

Quote:
Originally Posted by Brooks Graham View Post
...it's more than just an apparent illusion. This looks exactly like a changing DoF to me.
DoF only refers to the in focus parts of an image. The background blur and other out of focus parts of the image are not a part of DOF. That said, making the DOF thinner does have the effect of increasing background blur in relation to the subject. In the case of back-up-zoom-in, the increased background blur is caused by magnification, not DOF.

Quote:
Originally Posted by Bill Ravens View Post
I think the point Simon was wanting to make is that zoom/tele lenses don't, TECHNICALLY speaking, create a more shallow DOF. It only looks like it.
It does not look like it.

Shallow DOF is more blur on everything, including background and subject.
Back-up-zoom-in is is more blur on just the background.

Those are two very different things. DOF blur is different than the blur caused by magnifying the background, but it's close enough. In any case, the additional blur on the subject means that they do not look the same unless there was nothing in the image between the background and subject and the subject was thin enough already to be unaffected by the thinner DOF.

It comes down to knowing this: background blur and DOF are different and have different contributors.
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Old January 16th, 2009, 06:19 PM   #57
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Please, then, explain the differences in the fence area of the images I posted a few pages back.

In the first image, it's out of focus. (long focal length)

In the third image, it's in focus. (same f-top, shorter focal length)

According to what y'all are saying, they should be identical if focal length has nothing to do with "real" focus.

And yes, I agree that longer focal lengths have other effects like spatial compression. But my eyes aren't hallucinating.
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Old January 16th, 2009, 06:51 PM   #58
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Originally Posted by Brooks Graham View Post
Please, then, explain the differences in the fence area of the images I posted a few pages back.
I thought everyone in this thread was talking about back-up-and-zoom. In your post, you're talking about *just* zoom, with no backing up. I misunderstood what you wrote. You are quite correct that changing focal length without compensating by moving the camera causes a change in DOF.

Your demonstration proves that tighter compositions have thinner DOF. That is, an extreme closeup has thinner DOF than a headshot. A headshot is thinner than head-and-shoulders. Then waist-up, full body, environmental portrait, etc. But what if someone wants to do a full-body portrait with blurred background? Telling them to zoom in to a headshot wont help, because then it's no longer a full body. One option is to backup really far and zoom in to compensate. Then it's still a full body shot, but the background has magnified blur. That's what I understood this thread was mostly about.
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Old January 16th, 2009, 07:14 PM   #59
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Let us also not forget the affect that aperture blades have on the out of focus areas of an image.... Why some lenses are sought after for the "bokeh" the render, like that of the canon ef 85mm f1.2 L lens or my favorite, the carl zeiss V mount 110mm f2 with it's 10 blade iris.

I also enjoy seeing the hot spots in the bokeh from anamorphic lenses.... ovals.
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Old January 16th, 2009, 07:17 PM   #60
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Yeah, there's been several conversations taking place here ... and I'm not helping ;-)

But my issue is that very strong statements have been made here that focal length does not and cannot have any impact of DoF - that it's all some magical magnification effect of pre-existing softness. I'm just calling bs on that and providing actual images that say otherwise.

The results of my testing, btw, comparing the DoF of the EX3 with stock lens against the FX1 with various distances from the subject, etc., the differences were significant enough (for the kind of work I do) to justify the acquisition cost of the EX3. For me, having more control is key. On the FX1, it seemed that achieving anything but 1' to infinity was a rare edge case - okay, a bit of an exaggeration, but you know what I mean. The EX3 gives me more creative choices in a camera of its form factor (and price). I'm happy.

Sorry again for the hijack, but this side-thread actually was relevant in some ways to the original question.
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