Depth-of-Field

Does anyone know where I might get depth of field charts for the XL1s with the 16x 5.5-88mm lense? Or does anyone know the circle of least confusion for the XL1s image sensor?

[Chris Hurd]

I think this will be a tough request to fill due to the way that lens works, but I'll try to check my sources.

[Kevin Triplett]

I've been working on a depth-of-field calculator for the XL1 ... the problem is determining the true image size of the sensor. The way the lens works may or may not be a problem.

Hey Chris, since you know some of the Canon folks, would you pump them for this information? It would be really helpful for us DPs out here who are trying to create stunning images with this beast.

Thanks!

I just recently noticed that the focus ring is "tweaky". As if it wasn't bad enough there are are no distance markers, I found that I can't mark the ring manualy, if i get a good focus and mark it with tape, adjust the focus and then move back to the marker, the focus isn't maintained. This is becoming a Pain, and i really can't afford the manual servo lense. :( A D-o-f calculator under these conditions might be tricky.

[Rob Lohman]

I found this on the web:

---
For Canon XL-1 Wide Angle

F4 with subject at 3m depth of field is 1.4m-infinity
F4 with subject at 2m depth of field is 1.2m-19m
F4 with subject at 1m depth of field is .8m-2m

F5.6 with subject at 3m depth of field is 1.2m-infinity
F5.6 with subject at 2m depth of field is 1m to infinity
F5.6 with subject at 1m depth of field is .7m-3m
---

I assume they are talking about the 3x lens here

[Adrian Douglas]

The reason your focus isn't maintained is because there is no mechanical link between the focus ring adn the focus mechansim. It's servro operated, all the ring does is tell the servo to shift the focal plane.

There are cheaper manual lens options, the Fujinon 14x. You can pick one up from ZGC, one of Chris's sponsors for around a grand US. There are a few second hand ones around to now the 16x Canon lens is available.

[Chris Hurd]

Kevin -- my next opportunity to enter Canon-space is Feb. 11th at the New York DV Conference; will try to get this answered there.

[Gabor Kertai]

http://arenafilm.hu/dof.php

[Kevin Triplett]

Awesome! Thanks, Gabor

[Richard Grebby]

im kinda new to cameras although im getting there mainly through trial and error and reading books, but can someone help me with the table on the link?

Ive been trying to get depth of field to work well with my XL1 but have found that I must have the lens zoomed in close to enable any kind of focus change.

Could someone help me out and tell me how to read the table and which bits are important that would be really great.

Thanks.

[Kevin Triplett]

You do have to zoom in to get a change in focus between near and far objects. And the wider the aperture/iris, the more this change in focus becomes.

The chart has an explanation in the upper left box. It's terse but looks complete. Basically, for the aperture setting and the focal length setting, the near and far focus distance and everything in between is in reasonable focus.

At the bottom of the page are links to other cameras/lens setups.

[Richard Grebby]

I feel like its one of those things that becomes natural when setting the camera location up.
I'll do some tests and have a mess around.

The thing im trying to is rack the focus from one face to another when two people are standing next to each other.

Maybe the best way is to do it using afteraffects....

[Kevin Triplett]

Yes, after effects would do the trick -- means more work but if you have control over the where the two faces are in the frame, you can minimize the amount of work. But you have to consider the background and how it looks as you simulate rack focus.

Another way to do rack focus is to let the camera do it for you -- focus on one of the faces and then let the auto focus focus on the second face. Would mean panning or setting up the shot so that the second face is the one the camera *wants* to pull into focus. Would have to do it several times before you get it right.

If you have access to a manual lens, it's *much* easier. But if you have a good monitor, you can rack focus the standard lens, it's just more tricky, you have to practice it and turn the ring at the same speed each time. If you're filming a scripted scene, you run the risk of losing a good take with a botched rack focus. Ah, the joys of servo focus!

Wait a tick -- did you say "standing next to each other?" That's odd, it's terribly difficult to rack focus between two people standing next to each other. I'm sure you are describing something else, surely they are standing next to each other but are actually at different distances to the camera? Otherwise, you would totally have to do it in after effects and then you wouldn't have to worry about how it looks, cause it would probably look surreal regardless. :)

[Richard Grebby]

sorry I ment when one person is standing closer to the camera. Its just something I need to work on I guess.