Jump to content


Photo

Decreasing Depth of Field in Video


  • Please log in to reply
19 replies to this topic

#1 Yaron Y. Dahan

Yaron Y. Dahan
  • Basic Members
  • PipPip
  • 38 posts
  • Student

Posted 21 December 2006 - 01:41 PM

This question just came up in another topic, tangentially, and I wanted to dedicate its own topic to it.
So the question is, how can I minimize the depth of field in order to get a most filmic look?
I am relatively new to video, and I'm not very fond of that evrything always in focus look.
I know that ultimately I have to do tests to figure it out, but I have heard of situations where people played with backfocus, or even removed the lens and held it a couple of millimeters away from the body in order to get a short depth of field. Has anyone tried any of these? Do they work? Do you have any other ideas recommendations as to getting a shallow depth of field? any way to get those drastic changes in focus that one can get with film?
  • 0

#2 Jason Debus

Jason Debus
  • Sustaining Members
  • 311 posts
  • Student
  • Los Angeles, CA

Posted 21 December 2006 - 02:01 PM

There are two main methods that I know of:

1. Shoot wide open - this may require NDs if you are shooting in daylight or bright light
2. Use long focal length - I'm not entirely sure this actually decreases depth of field but it does increase the appearance of shallow depth of field.
  • 0

#3 Matthew Bennett

Matthew Bennett
  • Basic Members
  • PipPip
  • 38 posts
  • Director

Posted 21 December 2006 - 02:12 PM

So the question is, how can I minimize the depth of field in order to get a most filmic look?


What camera?

With the DVX100A you have to open up the f stop as much as possible and put a lot of BG distance behind your subject. Also, you can shoot macro which gives you very nice shallow DOF, but of course only allows you to shoot extreme closeups.
Also there are the huge variety of 35mm lens adapters to choose from...
  • 0

#4 Matt Frank

Matt Frank
  • Basic Members
  • PipPip
  • 78 posts
  • Cinematographer
  • Pasadena, Ca

Posted 21 December 2006 - 02:50 PM

There are two main methods that I know of:

1. Shoot wide open - this may require NDs if you are shooting in daylight or bright light
2. Use long focal length - I'm not entirely sure this actually decreases depth of field but it does increase the appearance of shallow depth of field.


A diffustion filter such as a Tiffen SoftFX also helps take away the video look.
  • 0

#5 chuck colburn

chuck colburn
  • Basic Members
  • PipPipPipPip
  • 389 posts
  • Other
  • orygun

Posted 21 December 2006 - 03:00 PM

This question just came up in another topic, tangentially, and I wanted to dedicate its own topic to it.
So the question is, how can I minimize the depth of field in order to get a most filmic look?
I am relatively new to video, and I'm not very fond of that evrything always in focus look.
I know that ultimately I have to do tests to figure it out, but I have heard of situations where people played with backfocus, or even removed the lens and held it a couple of millimeters away from the body in order to get a short depth of field. Has anyone tried any of these? Do they work? Do you have any other ideas recommendations as to getting a shallow depth of field? any way to get those drastic changes in focus that one can get with film?


Hello Yaron,

Depth of field is a function of focal length, f-stop and chosen circle of confusion diameter. Moving the lens away from the film plane only results in an out of focus image.

Chuck Colburn
  • 0

#6 Stephen Williams

Stephen Williams
  • Sustaining Members
  • 4708 posts
  • Cinematographer
  • Europe

Posted 21 December 2006 - 03:03 PM

Hi,

Stretching a fine net behind whatever you want in focus will soften the background.

Stephen
  • 0

#7 Stephen Press

Stephen Press
  • Basic Members
  • PipPip
  • 74 posts
  • Cinematographer
  • New Zealand

Posted 21 December 2006 - 03:21 PM

It depends on the camera but most newer professional cameras have -3gain you need to set it in the menu. You can put black nylon stocking in the mount between lens and camera. Ad smoke with a ****ing smoke machine? I hate smoke machines, they really slow a shoot down but they can look good.
An easy way of decreasing your DOF is to turn up the shutter as it uses more light but is often ugly and distracting to look at so not recommended.
2x extender uses more light and lots of people seem to forget its there.
Of course the very best way of decreasing your DOF is simply with less light. Get some dimmers and bring your light levels down. At end of the day the secret to good looking video is all about less quantity of light and more quality.
  • 0

#8 Jonathan Bowerbank

Jonathan Bowerbank
  • Basic Members
  • PipPipPipPip
  • 2815 posts
  • 1st Assistant Camera
  • San Francisco, CA

Posted 21 December 2006 - 03:41 PM

Using just my cheap Digital8 camera, I was able to get a really nice shallow DoF by just moving the camera away and zooming in on my subject, therefore increasing my focal length.

It's pretty simple, just play around with your video camera and see what you're able to do.
  • 0

#9 Daniel Smith

Daniel Smith
  • Basic Members
  • PipPipPipPip
  • 791 posts
  • Other

Posted 21 December 2006 - 03:43 PM

I'm trying to get hold of some examples of this myself but a friend of mine shot a film out in Bulgaria with an XL1s with a 'Tiffen Black Pro-Mist' filter. Generally all they do is soften the contrast but don't create as much of a 'halo' as a standard pro-mist filter.

It won't directly affect the depth of field... unless it cuts down on levels of light and forces you to open the iris even further, but it will certainly help remove that sharp digital look that a lot of people don't like. (Personally I don't mind it.. it's purely subjective)

Edited by Daniel Ashley-Smith, 21 December 2006 - 03:44 PM.

  • 0

#10 Joshua Provost

Joshua Provost
  • Basic Members
  • PipPip
  • 71 posts
  • Cinematographer

Posted 22 December 2006 - 02:07 PM

Yaron,

Some of the best suggestions were covered, but I'll just add a little.

1. Shoot with the iris as open as possible. There is a catch to this. The iris may be able to open to F1.6 or so (don't know what camera you're using) when at full wide, but only F2.8 when full zoomed. To maintain flexibility, I usually establish the lighting to F2.8 or above, and use ND to bring it right to F2.8. That way I can go full wide to full zoom without changing exposure. You'll need a variety of ND. My DVX has 3 stop and 6 stop built in. I keep a 1 stop and 2 stop around to get in between increments.

2. Zoom in. Example: If you want to shoot a close-up, you can go full wide and put the camera right in front of the person, or you can go full zoom and back the camera up. Either will get you a close-up, but the zoomed one will have a shallower apparant depth of field, becaue the field of view is so small. The background gets blown up so you see it is out of focus. Now, extend this beyond just close-ups. Even medium shots you can probably still back the camera up as far as possible and then zoom in. This is huge. It's probably a more dramatic depth trick than even the iris.

3. Adjust camera sharpening. This is huge. Nearly all cameras do a great deal of sharpening. The camera is fighting against your shallow depth of field. It is taking out of focus objects and sharpening them to make them seem like they are in focus. On my DVX, I have turned the Detail setting all the way down. The image is still sharp exactly where the focus is, but nice and smooth everywhere else. Beyond that, sharpening is just ugly. Check it out, I think you'll be pleased.

4. Light for depth. In B&W, you have to use light to show the depth of the scene and to isolate obejcts. Not so in color, but you can still light for depth with pools of light at different distances, and rim lights to set objects off from the background. This doesn't really effect depth of field, but creates pleasing perceived depth in the scene.

5. Block for depth. Given any shooting environment, position the camera and talent to create distance between them and the background. You can't stick people against walls and expect to get shallow depth of field.

6. Compose for depth. Many people tend to clear out the space between the camera and the talent, but it can help to have foreground objects that will be out of focus. Position the camera to shoot through and around these obejcts. Also, make the background interesting, but not too interesting, so it creates a nice image but doesn't distract.

7. Camera movement. Any type of camera movement (pan, tilt, dolly, jib, crane) will give great feeling of depth because you can see the dimensions of the space change as the camera moves. This is particularly true of dolly in/out and across scenes, and jib up/down. With these movements, the shallow depth of field isn't as important, because you can sense the depth. Shallow depth of field is only a big factor on static shots.

There you have it, two lensing suggestions that actually effect depth of field, one camera tuning suggestion, and four non-camera tricks.
  • 0

#11 Stephen Williams

Stephen Williams
  • Sustaining Members
  • 4708 posts
  • Cinematographer
  • Europe

Posted 22 December 2006 - 02:17 PM

Using just my cheap Digital8 camera, I was able to get a really nice shallow DoF by just moving the camera away and zooming in on my subject, therefore increasing my focal length.

It's pretty simple, just play around with your video camera and see what you're able to do.


Hi,

You were shooting close ups or medium shots, try a person standing head to toe, the background won't go soft!

Stephen
  • 0

#12 Jay Gladwell

Jay Gladwell
  • Basic Members
  • PipPipPip
  • 144 posts
  • Miami, FL

Posted 22 December 2006 - 03:48 PM

Stephen, what's the prize for those of us who could accomplish your challenge?
  • 0

#13 Stephen Williams

Stephen Williams
  • Sustaining Members
  • 4708 posts
  • Cinematographer
  • Europe

Posted 22 December 2006 - 03:58 PM

Stephen, what's the prize for those of us who could accomplish your challenge?


Hi Jay,

It was not a challenge :D The word 'greenscreen' springs to mind!

Stephen
  • 0

#14 Jay Gladwell

Jay Gladwell
  • Basic Members
  • PipPipPip
  • 144 posts
  • Miami, FL

Posted 23 December 2006 - 09:02 AM

Understood, Stephen.

I know you know this, but it's all relative. One could shoot a full-figure shot and have the background out of focus. It would simply require that the relative distances from b.g. to subject and from subject to camera be increased with the lens at it's longest focal length.

;)
  • 0

#15 Chris Keth

Chris Keth
  • Sustaining Members
  • 4427 posts
  • 1st Assistant Camera
  • Los Angeles

Posted 23 December 2006 - 09:40 AM

There are only two things that affect depth of field. 1.) Enlargement size on negative (or sensor) and 2.) f/stop. Since you won't want to change enlargement size (it would give you different framing) your only choice is to shoot as wide open as you possibly can.
  • 0

#16 Yaron Y. Dahan

Yaron Y. Dahan
  • Basic Members
  • PipPip
  • 38 posts
  • Student

Posted 25 December 2006 - 01:11 PM

There are only two things that affect depth of field. 1.) Enlargement size on negative (or sensor) and 2.) f/stop. Since you won't want to change enlargement size (it would give you different framing) your only choice is to shoot as wide open as you possibly can.


well, actually, my question was more how to create the illusion o a shallow depth of field, rather than changing the depth of field itself, which as you mentioned only changes with aperture

thanks everybody for the suggestions and the advice, especially josh who took the time to write out such a long detailed response.
  • 0

#17 Stephen Williams

Stephen Williams
  • Sustaining Members
  • 4708 posts
  • Cinematographer
  • Europe

Posted 25 December 2006 - 01:25 PM

Understood, Stephen.

I know you know this, but it's all relative. One could shoot a full-figure shot and have the background out of focus. It would simply require that the relative distances from b.g. to subject and from subject to camera be increased with the lens at it's longest focal length.

;)


Hi,

Problem is the you will be fairly close to half the hyperfocal distance.

Stephen
  • 0

#18 Miguel Bunster

Miguel Bunster
  • Basic Members
  • PipPipPipPip
  • 301 posts
  • Cinematographer

Posted 25 December 2006 - 03:59 PM

well there a few things you can try and depends a lot on the situation you are in (exterior, interior, day night etc....)

Create layers of light helps to create the illusion of more or less depth of field...for example if you are inside a house and you have the FG, Middle Ground and Bg at same exposure it will look all sharp but if you play with FG under exposed, middle ground over and etc depending on lens and things you can create the illusion. AS well what helps a lot is to have FG elements really near the lens that will out of focus (but this is an artistic choice)...
See mixing as well hard light and soft light in different layers of the image as well if you have the BG in cold colors or warn depending on the FG...

Best
Miguel


Best
Miguel
  • 0

#19 Jonathan Bowerbank

Jonathan Bowerbank
  • Basic Members
  • PipPipPipPip
  • 2815 posts
  • 1st Assistant Camera
  • San Francisco, CA

Posted 27 December 2006 - 12:58 PM

well, actually, my question was more how to create the illusion o a shallow depth of field, rather than changing the depth of field itself...


You can also try lighting your subjects with some hard, crisp and contrasty lighting, while lighting the background with a lot of soft, diffused and perhaps a bit darker lighting. That'll give you an "illusion" of the background appearing a little out of focus.
  • 0

#20 Alexander Browne

Alexander Browne

    New

  • Basic Members
  • Pip
  • 7 posts
  • Student

Posted 27 December 2006 - 01:18 PM

I use one of these http://www.sgpro.co.uk/ - fairly inexpensive and effective (I think the pro35 etc do not justify there extremely high price - I would shoot 35mm if I had that much money) and this adapter is now available with PL mount if you want to rent lenses.

Adapters have some associated headaches - I've never tested it but my camera feels significantly less than 100 asa with it on. BTW, I'm not connected with the manufacturers in any way! Cheers,

Alex
  • 0


Willys Widgets

rebotnix Technologies

Opal

Ritter Battery

Metropolis Post

FJS International, LLC

Broadcast Solutions Inc

The Slider

Visual Products

CineLab

Aerial Filmworks

Technodolly

Media Blackout - Custom Cables and AKS

Rig Wheels Passport

Abel Cine

Glidecam

Gamma Ray Digital Inc

Tai Audio

Wooden Camera

CineTape

Paralinx LLC

CineTape

Ritter Battery

rebotnix Technologies

CineLab

Rig Wheels Passport

Aerial Filmworks

Paralinx LLC

Tai Audio

FJS International, LLC

Gamma Ray Digital Inc

Technodolly

The Slider

Opal

Metropolis Post

Abel Cine

Broadcast Solutions Inc

Visual Products

Media Blackout - Custom Cables and AKS

Glidecam

Wooden Camera

Willys Widgets