DOF tutorial for 35mm adapter users (20 min)

[snodart]

I made this for a DVD that never happened. Should be helpful for those using or planning to use a 35mm adapter.

It is a bit slow paced, but the info is all there. If the subject is new to you, you might have to watch it a few times for it to "click".

Feedback always welcome

Depth-of-Field Tutorial


EDIT (5/15/2007):

The DVD mentioned above was for the Snod35 DIY DVD/kit. Currently, I am no longer planning on making the DVD/kits (you can read why at the link below). However, I have posted a write-up (with pictures) on my website as to how I built the original Snod35:

Snod35 write-up

*Please post any comments and questions about the Snod35 to the thread at the link below*

Snod35 info thread

EDIT (10/14/2007):

You can also view a streaming version (flash) of the tutorial at FreshDV:

http://www.freshdv.com/2007/10/video...-of-field.html

or at Letusdirect.com

http://www.letusdirect.com/depth-of-...al-videos.html

EDIT (01/11/2008):

This is from an older post, but I though it might be helpful to add it here:

Below is from http://www.dvxuser.com/V6/showthread.php?t=71373

The reason that 1/3” CCD cameras are limited to a long DOF:

The target size is the size of the physical element that is capturing and recording the image in a given camera. In a motion-picture film camera, it relates to the size of the film. With a DV camera, the target size is the size of the CCD(s) that are recording the image and converting that information into a digital signal. In the case of most miniDV cameras, including the Panasonic dvx-100, the CCD is 1/3". 1/3” does not reflect the actual physical size of the sensor however. The actual width of a 1/3” CCD is somewhere around 5mm wide. Likewise, most 35mm film does not actually have a frame size of 35mm since some of the space is taken up by the perforations in the film and by soundtrack information. The actual frame width of 35mm is often closer to 22mm. So from this, we see that the target size of the 1/3” CCD camera is about 4 ½ times smaller than the actual frame size of 35mm film. What does this mean exactly? Let’s say we are using a lens with a focal length of 50mm for a 35mm film camera and for a 1/3” CCD camera; both of which are at the same distance from the subject.. The images below show how much of the subject each would see.




So, in order for the 1/3" CCD to achieve the same subject size in relation to the frame, we would need to do one of two things… either move the camera way back until the subject size is the same in relation to the frame (as compared to the 35mm frame), or use a lens with a shorter focal length. Always shooting from a great distance is not a very practical solution (and technically it lengthens the DOF anyway), so the better option is to use a shorter focal length lens. This would increase our field of view and allow us to obtain the same subject size within the frame... from the same distance as the 35mm camera (or a comparable distance anyway)..



This is why prosumer DV cameras have considerably short focal lengths. The Panasonic DVX100B for example has a zoom lens that ranges in focal length from 4.5mm to 45mm. Having a shorter focal length essentially compensates for the very small target size. Since a short focal length inherently creates a long DOF, 1/3” DV cams are limited to a long DOF. You can always back the camera up and zoom all the way in so that the focal length of the DVX is at 45mm. Though technically the DOF would be the same, visually it appears to be much shorter. The reason for this is an whole other can of worms...


END

[ennfurno]

hey,that tutorial was great and very informative.thanks alot for sharing.

[slimchrisp]

rock! thanks for sharing man. i know there have to be hundreds of hours of work in that information. much appreciated.

[Wayne Kinney]

Brilliant!

[Hans Moleman]

wow

i actually learned something.
i retained information!

you should teach.

[snodart]

Thanks all.

[jgastelb]

I like the way you're presentiing this. It does not, however, let me download it to my computer.
Jgastelb

[snodart]

Thanks jgastelb. To download, you need to save the file. For example, if you are using IE and windows: right click and "Save Target As".

Thanks for taking a look.

[kledster]

wow these are excellent. very professional and very informative, thanks snodart!

[mrWr0ng]

I don't have a 35mm adapter (yet) but still found it very informative. In fact I was just referencing the video yesterday at a shoot when I was filming from behind the stage, figuring out how to keep the artist in focus while blurring out the audience. It worked perfectly.

Great video!