Now from what I understand, the bigger the CCD the shallower depth of field can be achieved, right?

My question is how much of a difference of a DOF there will be?
Say between the XL1 with 1/3" CCDs and something with either 1/2" or 2/3" chips?

I've looked up a few common chip sizes and I'll list some important details.

1/4 inch CCD. 3.2mm X 2.4mm. 4.0mm diag. Focal length mag. 11.3X


1/3.6 inch CCD. 4.0mm X 3.0mm. 5.0mm diag. Focal length mag. 9.0X


1/3 inch CCD. 4.8mm X 3.6mm. 6.0mm diag. Focal length mag. 7.5X


1/2 inch CCD. 6.4mm X 4.8mm. 8.0mm diag. Focal length mag. 5.6X


2/3 inch CCD. 8.8mm X 6.6mm. 11.0mm diag. Focal length mag. 4.1X


35mm Film. 36.0mm X24.0mm. 43.3mm diag. Focal length mag. 1.0X


Because I couldn't get the proper spacing due to software limitations let me explain the numbers. The first set is the common size of the CCD chip. Next is the width and height of the chip. The diagonal measurement is next and the focal length magnification factor is last.

The aspect ratio (height to width) is 4:3, except for the 35mm film, which 3:2. The diagonal is listed for two reasons. A rough equivalent to the normal focal length is derived from the diagonal (35mm film is 43.3mm diag. 50mm lens is considered normal). Some people use the diagonal to derive the focal length magnification. The 7.2 magnification factor used by Canon (for use of EOS lenses with EF adapter) is obtained by dividing 43.3 by 6.0 (the diagonal of film divided by diagonal of 1/3 inch chip). My materials list the Focal length magnification using the widths (long dimension) hence the slightly different numbers.

Since we are not changing any of the components of the DOF formula, the DOF can be calculated as a percentage of the different focal length magnifications.

The DOF on 1/3 inch CCD's is 7.5X the DOF of 35mm film. DOF is 25% greater with 1/3 inch CCD's vs. 1/2 inch CCD's. A 2/3 inch chip has 27% less DOF than a 1/2 inch chip.

You can get real world measurements by using a DOF calculator (http://www.shuttercity.com/DOF.cfm) They are set up to show 35mm film DOF so the distance will need to be increased by the appropriate percentages derived by the information above.

Jeff:

Not faulting the math, but confused about something--I was always under the impression that 2/3" video and 16mm were approximately the same in terms of field of view at a given focal length, and that they were both roughly half of 35mm (2/3" video being more like 2.2x magnification and 16mm 2x). Obviously this doesn't agree with your table...help?

I don't know about the math, there may be a typo there. But, the basic physics is the same. The bigger the chip (or negative) the shallower the depth of field. I believe a 2/3" chip and 16mm film is close, though not exact. Some people consider a 50mm focal length to be "normal" in 35mm, and it's 25mm in 16mm, and roughly the same for 2/3", give or take a mm or two.
Practically speaking, there is quite a big difference between the depth of field you get with 1/2" and 2/3" chips. Not as big as the jump for 16mm to 35mm, or from 1/3" to 2/3", of course, but it's more difficult to get shallower depth of field with 1/2" chips. Even with the newer 2/3" chip cameras like the DSR500/570, it's difficult under long shot conditions, because the cameras are so light sensitive you're usually stopped down quite a bit. I always shoot at a -3db with the DSR500 and have only taken it off that setting one time for a night exterior shot.

Charles,

Do you have the dimensions for Super 16, Academy 35 and Super 35? I used 35mm still film as the basis for the factors. I believe 35mm motion picture film varies from still film and is the cause of the confusion.

Bill,

Thanks for catching the typo. That'll teach me to write these things before my first cup of coffee.

Jeff

Re: "That'll teach me to write these things before my first cup of coffee."

Yeah, but Bill has a new coffee maker, for that better cup of coffee. That's why he keeps on humming. He only paid $160 US for it.

I've read that 1/6" CCDs almost gives a 3D look, so what kind of look would a cam with mega pixel 1/8" CCDs give you? 3D?

sorry about the inches...
Super 16: .486x.295
Full ap 35: .980x.735
35mm 1.85 ap: .825x.446
Super 35 (2:40:1): .945x.394 (extracted)
Anamorphic projection ap: .825x.690

I used the long dimension to calculate the magnification factors. On 35mm still film its 36mm or 1.47 inches. Big difference between 1.47 inches and .945 inches on Super 35. I'll add the film sizes to the chart in a couple of days. I'm going to be out for a couple of days for surgery on my shoulder. Too many years of carrying Betacams, tripods, light kits etc.

Great info. Thanks Jeff et. all!

Just a friendly reminder that while shallow DOF is part and parcel
to the Pro Look, it is not the entire affair.Long before long lenses even showed up,filmmakers were doing just fine with what they were dealt at the time,which included mostly wide shots done with limited focal length lenses.A recent example of that "old school" stuff was brilliantly executed by Owen Roizman ASC for "Wyatt Earp".If you haven't seen it in a while,watch it again-it is well worth it.

If I heard as much about composition on some of these boards as I did about shallow DOF,I would be greatly heartened.We would also see way more examples of fine cinematography on the various short film websites than we are seeing now.

Shallow DOF is a subject second only to the "film look" in terms of the frequency that it is discussed.

But composition should be number one among these three,because without it,we are nowhere.I believe it is the most important aspect of any production as far as acquisition is concerned.You may not always have what you want to shoot on,and you may not always have super long lenses......


But,you will always have that little "window on the world" to work with....

Just to support what "skyy" says in a more recent example, I hope you will all take a good look at "Signs," now that it is available on dvd. Tak Fujimoto's lighting and compositions are fabulous, and, surprise! Deep focus. That's right. For almost the entire movie there are no blurry backgrounds. But still, the DP is able to separate the people from the backgrounds (when he wants to). How does he do it? Rent the movie and find out.

Of all the things first time film makers should worry about, depth of field is way down the list.

If i throw this into the mix i have found using the sony pd150 is almost the same in operation as super 8mm when it comes to DOF and so on. I can imagine it must be similar in size.

Zac

Composition is extremely important. But unless the camera operator has prior education or experience, appropriate composition is going to take time. It's not something learned by books or forums (which I presume is why it is not discussed much). Composition many times goes unnoticed (an indication of good composition). The scene looks so natural it doesn't call attention to itself. Teaching natural elements of style and composition is tough.

DOF on the other had is more easily seen and noticed by novices. The results, good, bad and mediocre are easy to see. It is also easy to discuss and to teach. Basically use small numerical F/number for a shallow DOF and large numerical F/numbers for large DOF. Try teaching composition in one sentence.

<<<-- Originally posted by Jeff Donald :
DOF on the other had is more easily seen and noticed by novices. The results, good, bad and mediocre are easy to see. It is also easy to discuss and to teach. Basically use small numerical F/number for a shallow DOF and large numerical F/numbers for large DOF. Try teaching composition in one sentence. -->>>

It may be "easy to teach," but in the real world it is not easy to control with small chip dv cameras. So much time and effort is seen in posts to this and other forums trying to achieve narrow depth of field with these cameras, and it ain't gonna happen. Its laws of physics. So rather than bang your head talking about $7000.00 solutions on a $3000.00 camera to reduce depth of field, maybe time would be better spent studying a film like "Signs" and seeing how deep focus can work to the filmmaker's advantage.

Yes, composition takes time to learn. So does lighting, so does editing. So what else is new? Read my signature.

Shallow DOF can happen with small chip cameras.
I'm sorry,but,while I appreciate what larger chip cams can have to do with shallow DOF,it is not the entire affair.

A nice healthy zoom lens ratio has more to do with it.Anything from 16x and above will do.

As does the distance between your cam and your subject and also the difference between your subject and the background.

The above,(besides the other things that have been brought up already) is basically it.

And I am not going to explain it here for the umpteenth time because there is some else whose text is more timeless.

Pick up "Cinematography" by Malkiewicz.He will explain all that you need to know.

I can get "shallow" with my humble little Sharp Hi 8.
Or any other instrument,for that matter.....


Quit obsessing about chips and whatnot...

....obsess about *knowledge* instead....

skyy3838, in my obsessing about knowledge, I would like to know whyA nice healthy zoom lens ratio has more to do with it.Anything from 16x and above will do. is so important to controlling DOF?

Wayne, deep focus is easy to achieve and just about everybody's relatives do achieve it. That is why DOF is so talked about, it's difficult to understand (Laws of Physics) and most people have a difficult time achieving shallow DOF.

>>If I heard as much about composition on some of these boards as I did about shallow DOF,I<<
After watching Tadpole last night. I've been thinking of nothing else other than composition.
The shots were composed well enough througout the movie, I didn't care about DOF, or even notice for that matter. The DP made sure my eyes were always led to the area on the screen I was supposed to be looking at. Composition!!!! Who'd of thought:).

With color enhancement and flattening, it turns out, that was enough. All the shots were deep and the only reason I noticed was because at first I was studying the film. After about 15 minutes, I just sat back and enjoyed it. It may have not looked great on the big screen, but on my large screen TV it looked fine.

So... good lighting, good sound, good compostion, good story, good acting, good cinemetograpy, good editing, dont worry
about DOF.

I, too, watched Tadpole tonight and thought it was pretty darn good, especially for its apparently low technical budget. The only distractions to my eyes during the first few minutes were the shaky handheld shots (they should have hired Charles P.) and the color. But I, too, just settled into the story after 15 min.

In my view it is important to understand, but not bemoan, the apparent DOF limitations of small-chip/aperture cameras. Years ago, while working in IT, I would often become frazzled by non-IT people who became frustrated when they realized that the magic of technology could not deliver a specific solution, which they had formulated sans knowledge of technical capabilities, to a problem. If only they had come to IT with their -problem- and not their imaginary solution we could have saved hundreds of meetings and many hours of swordplay.

So it is with any form of imaging technology and story-telling. Framing your visual solutions knowledgably within the context of your capabilities from the start is the most productive and effective path and always has been. Spending many hours in post to create false DOF, as one pro I know recently did, reflects a poor imagination and weak problem-solving skills.

Regarding composition, I don't think we talk about it much because it's hard to teach/learn the art of composition on a forum.
Agreed, composition is much more important than DOF.

<<<-- Originally posted by skyy3838 : Shallow DOF can happen with small chip cameras.
I'm sorry,but,while I appreciate what larger chip cams can have to do with shallow DOF,it is not the entire affair.

A nice healthy zoom lens ratio has more to do with it.Anything from 16x and above will do.


Well then, "Skyy" I guess you will be happy to post some frame grabs taken with a mini dv camera that have shallow depth of field. Nothing too spectacular, just a standard head shot done in an interior, similar to shooting an interview in a room, exhibiting narrow depth of field. Please include pertinent information regarding what camera, f-stop, focal length, etc, along with the stills. I look forward to the pictures. Always happy to learn new skills.

A question for Jeff Donald.

Jeff,
I entered some data into the DOF calculator you posted earlier in this thread: Using XL1-s with a 300mm focal length lens, f/5.6, subject 20 ft away. the DOF calculator said DOF=5 inches for 35mm film. If, as you suggested the DOF for a 1/3 inch CCD is 7.5 times as much, my DOF would be over three feet! My subjects go out of focus if they move a few inches. What exactly do you mean by depth of field...it certainly isn't the region of sharp, or even acceptable, focus.

It is an error in the DOF calculator. When subject distances are less than 10 times the equivalent focal length (300mm X 7.2 = 2160mm) DOF calculators become unreliable and magnification tables need to be used. I believe that calculator uses a larger Circle of Confusion dimension then would be acceptable for 1/3 inch chips and larger than what might normally be used in determining 35mm DOF.

In your example I get 4 1/4 inches with 35mm film. Because of the extreme magnification we get with 1/3 inch chips the DOF drops to 2 inches. If instead I move back from the subject to 140 ft my DOF is 5 ft 11 1/2 inches.

There is no definitive size for COC. This is why the DOF figures don't work out exactly to the 7.5 times figure also. The generally agreed upon limits are between .033mm to .08mm. The differences in COC is a factor of almost 3 which is why DOF calculators give different readings.

<<<-- Originally posted by Dylan Couper : Regarding composition, I don't think we talk about it much because it's hard to teach/learn the art of composition on a forum.
Agreed, composition is much more important than DOF. -->>>

Yes,composition *is* a tough topic for the 'boards because after learning the basics(technically speaking) composition will have more to do with your artistic good sense from there on out.And that can only be dealt with by practice-because theory only gets your foot in the door.And then you ask yourself the tough questions:What sort of feeling about this scene do I wish to convey?Menace,melancholy,madness?How do I make Darth Vader look more towering? High Angle,or real low?Composition is real tricky because a large amount of it depends on the surroundings in which you are shooting.And sometimes,there doesn't seem to be a camcorder with a depth of field large enough to convey what you want to,so,you improvise and hope everything works out,somehow,after all.Are those pair of mountains, not being shot to your satisfaction unreachable by car, foot,zoom lens or different angles, and you don't have the money in the budget to charter a helicopter or plane to get you out for the perfect shot?
Well,that might be a problem that can be somewhat rectified in post,by whatever methods or software are available to you.

In terms of composition,you have to learn to activate your minds
"camera eye" so you can spot the shots that you want to commit.
Watch the movies that have cinematography that you particularly
admire so you can use some of those shots at a later date in your own production,if the context applies.
Remember comic books?Those things are incredibly rich in both storyboards and perpetuity-The producers of "Men in Black","From Hell" and "Road to Perdition" know this all to well,I reckon.

Yeah,compostion.It's pretty much a lifetime study.....

Best way to teach newbies composition is a Polaroid camera. It's almost a complete square frame. Instant feedback too, although a bit expensive,,, you could say that the low end digital still cameras are also a good way to study composition. It's definitely a good practice for those who tend to hit the Record button and start recording as soon as they see something in front of them, rather than let the object they are seeing present itself to them before pressing the Record button,,, I always try to look for S-curves in the frame, which can be used effectively to lead the eye of the viewer with a bit of imagination. If someone wants to improve their composition skills, I would also suggest taking drawing and painting classes, along with some art history classes. Many adult continuing education centers offer decent art classes for resonable fees. You don't have to go to a Juliard-level institution to study these things. The key is to start thinking about it more often than you did before, practicing it in a group setting and learning from others is extremely helful in shortening the learning curve. Also, find out what museums exist in your area and become familiar with their schedule and offerings. I love visiting museums and art exhibits whenever I can, the more styles you can expose yourself to, the better. My overall favorite "mentor" to learn from would clearly be Monet. That is an excellent starting point for learning about composition.

- don

Practically, here's the film school skinny on Depth of Field....

For a given focal length, a larger aperture (smaller f/number) provides a smaller DOF; a smaller aperture (larger f/number) provides greater DOF.

For a given focal length AND given aperture, a closer focus (distance to focused subject) provides smaller depth of field and a longer focus provides a longer depth of field.

For a given aperture, a longer focal length (telephoto) will produce a smaller depth of field, and shorter focal length (wide angle) will produce a longer DOF.

So if you are after shorter DOF: (1) Use the largest aperture (smallest f/number) you can, (2) bring the subject close to the camera, and/or (3) shoot telephoto as opposed to wide angle.

As total exposure is a result of both f/stop and exposure time (shutter speed) , changing one means changing the other to maintain correct exposure. If you open the aperture for decreased DOF you will also have to increase the shutter speed. Luckily, if you have an aperture-priority auto exposure, the camera will do this for you!

Cheers,
-Matt Ockenfels

Matt,

That only works if your image size can vary. Here is an article (http://www.dvinfo.net/articles/optics/dofskinny.php) that discusses DOf and here is a thread (http://www.dvinfo.net/conf/showthread.php?s=&threadid=3926) also.