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The challenges of creating Digital Cinema and other narrative forms.


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Old July 7th, 2005, 11:58 AM   #1
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Living with a WIDE D.O.F.

I wanted to hear some of your ideas as to how to create a more filmic/cinematic look with a wide D.O.F. This is for those of us who are stuck with a 1/3" or 1/4" miniDV camera and cannot afford the latest shallow D.O.F. devices. Thanks.
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Old July 7th, 2005, 12:23 PM   #2
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Camera movements help a lot. Framing is also something big. It takes some training, and a lot of finesse and practice.

I don't think it's something that I can easily put into words, but hopefully that can give you some ideas to play off of.
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Old July 7th, 2005, 12:33 PM   #3
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Glenn,

Usually DOF is referred to as shallow (only the subject is in focus) or deep (lots of stuff is in focus). I'll assume that by "wide" you are referring to the generally deep DOF of small CCD cameras, and you want to know what can be done without expensive or clumsy "35mm adaptors."

You'll want to work with the largest apertures your camera supports. This is usually between F1.4 and F1.7 on most cameras. My Pana GS400 is F1.6 when wide open.

However, these lenses are not very sharp at the extremes, wide open, or tight shut. They have "sweet spots" in between. So, you may want to target an aperture of F2 or F2.8. Also, the maximum aperture changes as you zoom. On my camera, at full zoom the max open aperture is F2.8. So, for me, F2.8 is a good target aperture because it's the most wide open I can get at all zoom levels.

Now, in a lot of circumstances F2.8 is going to be overexposed. In bright sunlight, completely overexposed. So, it's good to have a set of ND filters around to compensate. Ideally, you would have an ND3, 6, and 9 handy. That's 1, 2, and 3 stops compensation, repectively, and they can be combined, multiplied.

With those in hand, allow you camera to auto-expose the scene (or get an accurate exposure using a gray card and/or light meter). If it comes out at F8, you're 3 stops from F2.8, so throw on the ND9 and open the iris to F2.8. You're in business.

It has been mentioned before that you can back the camera up and zoom in, but that is inaccurate. The distance and zoom cancel each other out.

OK, those are all technical means. More of a logical suggestion would be to physically separate the talent from the background, as far as possible. If you put someone right in front of a wall, both them and the wall will be in focus. The further you can get them from the wall, the further the wall will be out of focus.

For instance, if you were shooting a scene in a restaurant, you wouldn't want to put the talent at a table in the back of the restaurant against a wall. The front or middle of the restaurant looking in would be better. Not only would the composition have been perspective, depth, and interest to it, but everything behind them would be progressively more out of focus.

And that's about all you can do. It's all math, relationships between focal length, distance from camera to subject, aperture, light, and the size of the CCD. Again assuming you need to compose a certain way, the distance from camera to subject and focal length (zoom) cancel each other out, you can only control the iris, and the light (sometimes), because it sounds like neither of us can afford a camera with a bigger CDD.
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Old July 7th, 2005, 12:57 PM   #4
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It's not true that distance and focal length cancel each other out. Longer lenses have a shallower depth of field, and that's true even with a DV camera's zoom lens. It can be difficult to see with some cameras, but it's true. If you can't see it at first with your camera then try it in an extreme circumstance (i.e. huge distance between camera and subject, huge distance between subject and background and iris wide open). You will be able to see that on the longer lens, the DOF is shallower. Otherwise Joshua gave you some great advice.

I think you should try watching some films shot with short lenses (and therefore with a deeper DOF). I would recommend the early Coen brothers films shot by Barry Sonnenfeld, especially Raising Arizona. He used wide lenses with lots of camera moves, and the movements rather than the DOF direct your eyes to the subject. It's a very cinematic look that doesn't require shallow DOF.
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Old July 7th, 2005, 01:26 PM   #5
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Glenn, this is a very good question and in light of what I would say is a near-rabid obsession with obtaining shallow depth of field in the DV community over the past year or so, I commend you for focusing on working with what you have.

You can create the sense of depth and separation through lighting. Allowing your subject to be slightly hotter than the background will "pick them out"; using a different color palette for foreground and background will also achieve this. For environments that had a lot of depth (i.e. seeing into the next room or beyond etc) try alternating bright and dark areas, i.e. pools of light.

Picking your angles and good use of camera motion will also propely your project into a cinematic realm. When possible, avoid wide shots with a lot of detail in the background, at least as static shots.

The first film I shot on DV back in 2000 (on a plain vanilla XL1), I immediately saw the challenges of the extended DOF of the 1/3" camera and applied these ideas. You can see the results at http://www.ifilm.com/ifilmdetail/2413801, although the film was put up at that site with more compression than they currently use so it's a little rough looking, but it may inspire some ideas.
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Old July 7th, 2005, 01:37 PM   #6
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Another aspect is the simplification of the backbround in your shot. When you look at all the methods everyone is mentioning here, its primarily to draw attention to the foreground and get the audience to either not see or ignore the background. This is easy with shallow DOF and that is primarily why its done. So another thing if you are filming in smaller rooms indoors is to eliminate all the unecessary background clutter...anything that takes away from your subject.

Another idea...though I've yet to try this one out yet so it might be the stupidest idea ever....but I've thought of filming all my close ups on greenscreen, then filming the background of the shot out of focus. It obviously won't have the fall off rate of true 35mm DOF...so it might look stupid...I'll get back to you on that.

Charles: Did that play on Sci-fi ever? I just started watching it and I could swear I've seen it before.
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Old July 7th, 2005, 03:12 PM   #7
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Going the greenscreen route will obviously complicate things and limit the camera motion--I'm not sure it's worth it unless you are building your backgrounds digitally a la Sky Captain & World of Tomorrow.

Zach, Josh did actually describe the phenomenon of varying focal length and depth of field correctly. Given a specific composition (say, a head and shoulders shot of a subject), by changing the focal length and moving the subject correspondingly to maintain this composition, the depth of field stays exactly the same.

Example (all at f2.8):
25mm, distance to subject 2 ft. DoF: near, 1'11"; far, 2'2".
100mm, distance 8'. DoF: near, 7'10", far, 8'2".
1000mm, distance 80'. DoF: near, 79'10", far, 80'2".

Interestingly enough, the 25mm actually has 1" less DoF than the longer focal lengths, but that is probably due to a rounding off.

However, if image size is not being maintained, then a longer focal length will indeed have a shallower depth of field. You can easily see this if you start with a wide shot focused at a near distance and then zoom in--the background goes progressively softer.

Matt: I don't know if that short played on cable. It's been to a bunch of festivals though.
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Old July 7th, 2005, 03:21 PM   #8
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DOF Test

Quote:
Originally Posted by Joshua Provost
It has been mentioned before that you can back the camera up and zoom in, but that is inaccurate. The distance and zoom cancel each other out.
This approach gets a lot of debate. But there's nothing like an actual test to see if it actually works. Take a look at the "DOF myths" section at the bottom of this DOF tutorial by Barry Green. There are links to two pics which clearly demonstrate that backing up and zooming in to maintain the same framing can yield a shallower DOF.
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Old July 7th, 2005, 03:26 PM   #9
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Zach, I have to emphatically disagree. Here is a quote from the dvinfo.net article The Ultimate Depth-of-Field Skinny by Jeff Donald:

Quote:
The three basic things (A, B, C above) that affect DoF are focal length of the lens, taking aperture and distance to your subject. In some cases, focal length of the lens and the distance to subject cancel each other out. How do they do that? By picking up your camera and moving it further away from your subject, you increase depth of field. However, your subject size may now appear too small. That's only common sense and easy to demonstrate with your camera. But how do we get the subject back to the same size as it appeared prior to moving the camera? We typically zoom the lens until the subject is larger. By zooming and making the subject larger, we have decreased the DoF (longer focal length, therefore less DoF). The Law of Reciprocity cancels the two changes out (longer focal length equals less DoF and moving away from subject equals more DoF). Your DoF stays exactly the same if the subject size is the same.
Basically it says that if need to get a Medium Close Up on someone, it doesn't matter if you are right next to them with a short focal length or far away with a long focal length, the DOF will be the same if the subject size is constant.

Further, the longer focal length will compress the space, creating a flatter image as illustrated here. Whereas a "normal" focal length of about 50mm produces a natural looking spatial dimension to the image.

Yet, focal length is not useless as a creative tool, for the reason of dimension just metioned. I just did a short film called Leonardo where we used exclusively medium and long focal lengths for the purpose of creating a flatter space with composition to create the sense of looking at a painting, rather than a typical film image, and we got the results we wanted.

I agree with Charles that lighting is very important, particularly lighting ratio of subject to background and a rim light behind the subject to set them off from the background.

Matt, as for simplifying your background, I partially agree. I think a great deal of attention needs to be paid to the background, but it almost always benefits from having some point of interest. Not enough to detract from your subject, but enough to create interesting images. Often a splash of light is also added to the background for this purpose.
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Old July 7th, 2005, 03:35 PM   #10
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Pete, I have to disagree. Look at the rear wall and vine in both images. It is equally out of focus in both.

The wide angle view is deceptive because there are other elements--the door, corner, side wall, and low wall in the front that are more in focus, as they should be. However, the rear wall, vine, gate, tree are all out focus.

Had the image been taken against a background perpendicular to the camera, it would be more obvious that DOF is the same in these situations.

You can't fight math, people.
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Old July 7th, 2005, 03:37 PM   #11
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It's ALL about layers and getting your viewer to "concentrate on a targeted area.

Movement in the BG is a good idea. If this produces a smudge or blur this is good! I've successfully now used ND solids and now Grads to "emphasise" areas I want . .er . .emphasised. To achieve real shallow DoF I now use filters to get to nearly 2nd and use a GRAD to "lift" an area.

When I first got my matt box and filters - Xmas 2004 - I was told, Grazie do all this in post, what you SHOULD be getting is a perfect shot and then applying Fxs - yeah? Nope! I use filters to now "prep" my camera. I think this is what is done in most "other" places too? Yes Charles?

I love this thread .. I can feel the creativity just about to spring up!

.. . Oh, BTW, what DOES a jiggling 35mm GG gizmo do?

Grazie
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Old July 7th, 2005, 03:55 PM   #12
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Quote:
Originally Posted by Joshua Provost
Pete, I have to disagree. Look at the rear wall and vine in both images. It is equally out of focus in both.
I guess we'll have to agree to disagree. :-)

To my eye, the dark green leaf and the wall are much more out of focus in the zoomed-in shot than in the wide shot. This is one of those deals where everyone can judge for themselves, and then go out and try it. Prove it one way or the other to yourself using your camera.
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Old July 7th, 2005, 04:32 PM   #13
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One of the times this was discussed here in the past, someone posted a link that illustrated a very wide angle and extreme telephoto setup, then blew up the background in the wide angle shot which revealed that they were the same.

It may be possible that the detail circuit in the DVX was responsible for the background of the wide shot looking sharper. I'm not sure.

Graham--Grazie--I myself have eliminated certain filters from my digital shooting arsenal that can easily be created in post, such as color tinting, but I use at least as much if not more contrast controlling filters, grads and polarizer as much of their effect cannot be duplicated in post. And the light control of a good mattebox can't be underestimated.

By the way, my thoughts are with you and your fellow Londoners--what a horrible series of events today.
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Old July 8th, 2005, 12:00 AM   #14
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I'm going with the math! Joshua and Charles, thanks for teaching me something new and confusing. When I was in school and constantly shooting with a PD-150, I thought I was getting shallower depth of field for interviews by backing up and zooming out, and all that time I must have been opening the iris without thinking about what it did to DOF.

But Joshua, I wasn't clear on what you meant by "composing a certain way" in your first post (trust me, after reading this thread, I am now). What I was thinking in mine and not expressing very well was that shooting lots of CUs on a long lens can give a bit of the Hollywood cinematic look because in the CU the depth of field is reasonably shallow. This is what I did for many of the interviews I shot. When I watch action movies or war epics (e.g. Troy), especially the ones shot with anamorphic lenses, I see long scenes that are essentially two CUs cut together with the DOF forcing me to look at the subject, who is always framed beautifully using that golden ratio. I don't know, Glenn, if you are going for the $135 million FX movie look, but I see that quite a bit. I most often see it in movies I don't like (again, Troy), and I suspect it may have more to do with easy editing for dialogue scenes than getting the best look, but it's there.

Taking a cue from a movie I do like, do you all think it's impossible to achieve a good cinematic look with a wide shot on a DV camera? I haven't watched Rules of the Game in about 4 years, but I remember that film uses a huge depth of field in detailed scenes quite often, and few people dispute that it's great cinema. Charles, you suggested that Glenn avoid this approach (wide shot, lots of detail). Is it impossible to achieve that detail with DV resolution or is deep focus just so rare a technique that no one will see it as cinematic unless it's clearly shot on film? Or am I totally misunderstanding this issue too? Now that I've read more on this thread, I'd like to see more suggestions for achieving a cinematic look without spending too many hours agonizing over depth of field, which, clearly, I don't yet grasp.
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Old July 8th, 2005, 01:07 AM   #15
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Zach, it may be helpful to check out Greg Pak's article on shooting Robot Stories for a film transfer. One good strategy is to avoid the pitfalls of DV, such as wide shots, due to the low resolution, as you mention. Play to the strengths of the medium and avoid its weaknesses.

Here's the latest short film I made, Leonardo. This is a three-minute cut of a six-minute film for a local filmmaking contest.
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