Shutter speed and it's apparantley super depth of field possiblities...?

[m0dsie]

Something I've been reading in a lot of places lately is that by altering the shutter speed on your camera (I use DV) you can "creativley" play with the depth of field.

I don't understand how this works. I can see shutter speeds being used to capture faster objects and what not but how does it affect the depth of field?

I usually just make a set with foreground, mid-ground and background objects, rather than adjust the shutter speed.

And does anyone have any shutter speeds tips and techniques? I find the fact it darkens things down annoying and not as easy to work with - but perhaps I'm just doing it all wrong, like, not setting the exposure right.

?

[twister!]

The shutter speed affects the amount of light coming in (because the shutter is either open for longer or shorter amounts of time depending on the setting you use). This therefore will allow you to adjust the aperture and hence the depth of field will change. The use of a zoom lens will also affect the depth of field.

Here's an article that probably explains it more clearly and in much more detail than I can (it gets quite technical but you can skip those bits if you like): http://www.dvinfo.net/articles/optics/dofskinny.php

<font color="#a62a2a" size="1">[ September 29, 2004 04:13 AM: Message edited by: Justin M. ]</font>

[eidde]

yeah, Justins right.
If you slow down the shutter speed you will get more light in your camera. This means you can increase the f stop (iris), and so increase depth of field.
If you speed up the shutter speed, less light will get in. Therefore open up the f stop (iris), and reduce your depth of field.

This can also be useful when you are using the same speed filmstock under different lighting conditions.

Adjusting Shutter speed can also affect the look of the film, and can create some pretty interesting effects.

[Nigel]

I am sure that they are DOF charts out there for Video. Where you could find them--Try the ASC Video Manual.

Now, that said. The problem with DV is that the CCD sizes are so small that you tend to always have a lot of depth. It is the same for Super8 film.

Here are a few examples using "Normal" lenses with the focus set to 10':

Super8 12mm Lens:
9'5' to ? at f1.4
1'7" to ? at f16

16mm 25mm Lens:
9'1/2" to 11'2" at f1.4
4'7" to ? at f16

35mm 50mm Lens:
9'7" to 10'5.5" at f1.4
6'8" to 19'10" at f16

DV with a 1/3" CCD is really close to the DOF of Super8 which means that even if you could get down to a f1.4 you still will see to ?. The thing to do for DV is to use longer lenses, NDs and slower shutter speeds. The problem with slowing your shutter speed lower than 1/50 is you will start to get a lot of blur.

If you have a higher end pro DV camera you can get adaptors to put longer lenses on but the CCD size means that they will greatly magnify compared to the format that they were intended for.

Good Luck

[Nigel]

For some reason it made my infinity symbols ?-marks...

Good Luck

[eidde]

hey thats a useful little table.
I agree with the super8 figures - Ive done a lot
of super8 filming and there isnt (in my opinion) any point trying to mess about with Depth of Field - in fact with some cameras it doesnt really seem to matter that much what you focus on (where you turn the 'distance' ring on the lens) it all seems to be in focus! (- or slightly out :-) most of the time)
Perhaps this is the same for lower end DV cameras.

[m0dsie]

Cheers for the links!

You're right sometimes everything is in focus, zooming in a bit an manually focussing normally does the trick. [img]smile.gif[/img]

[m0dsie]

Wooooo! Well I made a short on Sunday testing out some shutter-speed techniques and gooooddddamn it's a feature I should have played with far, far earlier. Superb depth of field effects and even better slow motion effects are possible too. Great stuff! Thanks for all the information [img]smile.gif[/img]

[twister!]

What kind of things did you do and what were the results...?

[m0dsie]

Justin, I remember now that it's easier to film rain with higher shutter speeds. Ala 21 Days Later.

http://screen7.adventuredevelopers.c...video/jump.avi (1.4mb)

Very good close-up stylee, without zooming and making a monster out of the foreground. That stuff - of which there's billions of - acquires a much better screen-time, not just two frames of blob.

http://screen7.adventuredevelopers.c.../speedaway.avi (1.6mb)

Clarity becomes the close-up key. You can read the writing on that leaflet. You're brain enjoys that clarity. In slow motion, and on a TV screen (avi's dont do them justice) - these clips look pretty awesome.

http://screen7.adventuredevelopers.c...itsnothere.avi (1.8mb)

aaaargh a zombie. No, that's just Joe. But it also captures those little grains that would normally be scattering far to fast for the lil ol DV camruh. Again, it picks up rain.

I read an 8mm camera manual the other day and it said used "creativley" you can get pretty funky with shutter speeds. I'm certainly liking it now.

Also, in another shot I zoomed in a little way with some branches in the foreground and shot Joe getting out of the car. The difference of the three grounds, foreground, midground & background were lush. The midground very solid, and at different distances too. Represents the human eye much nicer [img]smile.gif[/img]

<font color="#a62a2a" size="1">[ October 05, 2004 06:58 PM: Message edited by: m0dsie ]</font>