Depth of field and f-stop

[ChrisFigProductions]

My cinematography professor is at Brooklyn College's Film Dept once said "Shallow depth of field is a very important tool in the cinematographer's kit". I try to achieve shallow DOF as often as possible unless it doesn't help the shot in the story I'm telling.

Obviously with a 1/3 CCD, I have to zoom in as much as possible and get the F-stop to be 2.8. Otherwise, I'm stuck with everything in focus.

 

[AlexLucas]

My cinematography professor is at Brooklyn College's Film Dept once said "Shallow depth of field is a very important tool in the cinematographer's kit". I try to achieve shallow DOF as often as possible unless it doesn't help the shot in the story I'm telling.

Obviously with a 1/3 CCD, I have to zoom in as much as possible and get the F-stop to be 2.8. Otherwise, I'm stuck with everything in focus.

Shallow DOF is to better emphasize what you want, and remove what's unimportant to the story. However, I have to respect the rest of the shooters here, and say, don't overkill it with DOF. It's super noticeable, and people who do that are in danger of making a Letus35 or RedRock the kind of thing that becomes a stupid fad.

Also, shooting interviews from range to pull depth is a trick. It's available for only the daytime. The better way to get the depth and look you want is to drop a grand on lighting, and learn how to use it. Then it works in ALL CONDITIONS, not just on sunny or overcast days.

Most people complain in ENG about the time it takes to make it look good. Until they get the tape back. Luckily, at my shop, they know it's best to not mess with a photog's lighting time, unless it goes over seven minutes or so.

 

[2000lux]

I have to admit that I find it a tad ironic that Michael started this thread since he's such a proponent of little cameras.

Any way, chip size, aperture (f / T stops), shutter speed, focal length, gain, back focus (macro lens) etc. All these affect, and thus give you control, of the depth of field (DoF).

I use the aperture; built in ND filters; -3, 0, and +3 gains; shutter speeds (up to around 1/100); distance to subject and from subject to background; the macro feature; whatever I can use to get control of the DoF. Some times one can use a scrim behind the subject to help put the background out of focus, but you need time, and of course the gear.

You can crush the DoF with a small chip camera. You just need space to set up the shot. I shot this video with the JVC 110U camera which has 1/3" chips. To shoot the portrait shots I had to back pretty far away from the subject (~30') so I could zoom all the way in, and place the subject far away from their background (30' - 50' +). Then I used the ND filters to get me the widest aperture possible. In a couple of the normal B-roll shots I was able to back off and zoom in to get the background to fall off a little, but not often.

Suncoast Hospice

In this one you'll see an interview with the Chief of Police (it's near the end) in a huge room. To see most of the room in the background, we needed to put the camera and subject in a corner of the room. Because of the position, I had to leave the lens zoomed most of the way out for the wide shot. The camera, a Sony V1U, has 1/4" chips. Because of those facts, I couldn't put the background out of focus. Even though I was shooting wide open (maximum appeture), the whole background is rather sharp.

Disappeared

Some times you can use the macro option to do a nice rack. If you have a real lens, like on the JVC, or a full sized camera, you can focus on the farthest subject, and then refocus on the nearest subject with the macro ring. The background goes out of focus. When you want the far away subject to come in to focus, you just turn the ring until it snaps and poof! A nice steady rack focus. Again, it helps if you can zoom in a bit, if the subjects are significantly far apart, etc.

Some times I use the macro to put the background out of focus when shooting B-roll and won't even do the rack focus. I haven't tried it for an interview yet though. I'm afraid it might crush the DoF too much. Has any one else tried it?

 

[Ben Longden]

Ive been behind a camera since I was six, and it was not till I picked up Jon FAUER'S book "DVCAM a practical guide" that I realised that the Depth of Field management has another variable, other than

1) aperture,
2) camera to subject distance and
3) subject to background distance.

Its chip size.

Shooting 35mm for years (as a newspaper snapper) I was so accustomed to dialling in my desired degree of DoF it was second nature.

My first viddycam had (has... I still have it) a 1/3 inch CCD. My current workhorse has a 2/3 inch chip.

With the 1/3 incher, getting a defocussed background and foreground was nearly bloody impossible, as 2000Lux describes.

As soon as I used the 2/3 incher, it was like being back with the Nikons.... just dial up the DoF required...

Jon FAUER dosent go into the math or theory, but its there in black and white;

"Most consumer DV Camcorders use 1/4" chips, as does the DSR-PD100A.

"Sony's DSR PD150 and DSR-250 camcorders use 1/3" chips which are larger. The DSR-300A uses 1/2" chips which are about the same size as a 16mm frame.

"So material shot with the DSR-300A will have about the same DoF as a 16mm camera.
The DSR-500WS uses 2/3" chips which are slightly larger than a Super16 frame, and are the same size as high end HD camcorders.

"The larger the chip, the less depth of field, the more selective focus will be."

Ben


DVCAM. A practical guide to the system. Jon FAUER. ASC. ISBN 0-240-80480-5 Published 2001

 

[Michaelrosenblum]

Brian
I am seeing more and more DSLR's turning up in the bootcamps. This is a pretty good indication of where both the public and more marginal production entities like newspapers are heading.

 

[MtnShooter]

It's also an indication they have no concern for getting good audio.

 

[Michaelrosenblum]

amen, brother

 

[couryhouse]

review the audio problems... I was led to understand some of them have external mic plugs?

It's also an indication they have no concern for getting good audio.

 

[adam]

The irony is that the Canon DSLR's 44.1 khz is a better sampling rate than 48 khz, but harder to deal with.
I don't necessarily believe that the audio in a 5D, let's say, can never be good. If you get a good cable made up and hook it up to a Schoeps mic you'll be doing pretty well.
One of the reasons I believe so many print outlets are moving to the DSLR's is to leverage their massive investment in glass, and it makes sense for now.

 

[SimonW]

The DSR-500WS uses 2/3" chips which are slightly larger than a Super16 frame, and are the same size as high end HD camcorders.

2/3" chips are actually much smaller than Super 16mm.

A 2/3" chip is 11mm diagonal, while the S16 frame size is 14.55mm diagonal.

A lot of people get confused because they don't realise that a 2/3" CCD isn't actually 2/3"! So Super 16mm will actually produce considerably shallower DOF than a 2/3" video camera. I don't know who John Fauer is, but he was wrong.

The irony is that the Canon DSLR's 44.1 khz is a better sampling rate than 48 khz

In what way is having a lower sampling rate better than a higher one?

 

[adam]

The 44.1 versus 48 is, to my understanding, like this...

The range that you miss with the lower rate is essentially not audible in most scenarios. So you're not dropping much, if anything, in the way of sound quality. On the flip side, a lot of devices want to output 44.1 as opposed to 48. So the conventional wisdom with audio recording is to utilize 44.1 and avoid any extra conversions. The best example is that CD's are mastered at 44.1 and in the recording studio world that is often the default setting. 48 khz seems to be a TV and film thing. I don't know why.

Truth be told I don't understand much of it at all, just what was explained to me. It tells you what an afterthought video was by Canon's DSLR guys. They essentially flipped the video switch and then added what was believed to be "defacto" audio settings. They were only kind of right. I saw a demonstration where an Apple guy showed how you need to flip the audio in QT in order to edit in FCP. I'm guessing you won't see 44.1 from them again once they put the 5D guts (generalizing here) into an ENG form factor.

 

[couryhouse]

leverage the lenses!

Makes sense.... the price of those long fast f-stop lenses is pretty large...

i soppose i can just drop the 44.1 on the timeline in Sony Vegas and then it renders it out at 48k>? (Advice? Help?)

The irony is that the Canon DSLR's 44.1 khz is a better sampling rate than 48 khz, but harder to deal with.
I don't necessarily believe that the audio in a 5D, let's say, can never be good. If you get a good cable made up and hook it up to a Schoeps mic you'll be doing pretty well.
One of the reasons I believe so many print outlets are moving to the DSLR's is to leverage their massive investment in glass, and it makes sense for now.

 

[SimonW]

i soppose i can just drop the 44.1 on the timeline in Sony Vegas and then it renders it out at 48k>? (Advice? Help?)

You can yes. Vegas is excellent at handling that kind of thing transparently. FCP on the other hand is different. You use 44.1Khz audio in that system at your peril.

 

[couryhouse]

ok... Vegas actually started out as an audio editor.... in its deep roots... and accepts every plug in from the current sony audio stuff I think.

I know people with internet radio stations that use vegas 90 percent for audio... but once in a while edit some video. they swear by the audio handling ability...

I will tell you what sounded like crap one time though is I dropped a lower bandwith file into microsoft moviemaker and rendered out had a nasty sound to it....

,.

You can yes. Vegas is excellent at handling that kind of thing transparently. FCP on the other hand is different. You use 44.1Khz audio in that system at your peril.

Vegas is really pretty amazing... back when everyone was transcoding stuff to edit it.. I could just grab it seemed aby format and slap it on the timeline and VOLA!

 

[SimonW]

Vegas is really pretty amazing... back when everyone was transcoding stuff to edit it.. I could just grab it seemed aby format and slap it on the timeline and VOLA!

I can never understand why some people still see it is as a toy editor. As far as I am concerned it is one of the best out there. If only it had some sort of GPU support though.

 

[AlexLucas]

Yeah, one can get carried away with this DOF business. For example, slap a f 1.2 50 mm Nikon lens on your favorite DOF adapter and your DOF might be inches. Nose in focus, ears not. I suspect this obession with DOF will go the way of the "quad-split" (anyone else old enough to remember than one?

I have a 50mm 1.4. It's less than that. More like milimeters. I've had shots where the subject is looking at me in 1.4, and one eye is in focus, and one is not.
The camera is a Rebel XSi. APS-C sensor. Cropped.