maximising depth of field? limit of dslrs for video

[James Palanza]

so id really like to replace my last tape based video camera for weddings with another gh2, problem is this camera is used as like a long far away static shot at weddings and having everything in nice focus the entire range of the shot is important. Problem is, inside churches im wide open at like 1.4, so depth of field is super narrow. What i dont get is how my canon xl h1a can be wide open at 1.6 and still have everything in focus"!

[Les Wilson]

f-stop is only one thing that affects depth of field. The sensor size and focal length is also a factor. In this case the small 1/3" chips of the A1 is what's giving you lots of depth of field... the wider the shot, the more depth. Do some searching on "hyperfocal distance"

[Edward Carlson]

To sum up:

Shallow depth of field means less in focus.

All others being equal:
Large aperture (low F number) equals shallow depth of field.
Large focal length (or more zoomed in) equals shallow DOF.
Larger sensor equals shallower DOF.

So to get the greatest DOF (most in focus), use a small aperture (high F number, which menas more light), a wide lens, and a small sensor.

[James Palanza]

ah well i was aware of all of those but how the sensor size effected it! so it would seem this is not an issue i can simply work around with my gh2, thats rather unfortunate. hm well looks like I may be sticking to my tape based camera a bit longer!

[Les Wilson]

Originally Posted by James Palanza

...so it would seem this is not an issue i can simply work around with my gh2, thats rather unfortunate....

This is not true. Calculate your lens and camera's hyperfocal length and everything will be in focus from that point to infinity. There's app for it even. Google it.

[Chris Duczynski]

A far away static on a wide angle is going to create very few, if any, DOF problems. I'm sure you could shoot slower than F1.4, by throwing in a light for a bit more exposure just to be sure.
Anywhere up to about a 14mm should be fine.

[James Palanza]

Well I found some calculators, that is pretty helpful. I just didn't think so much about infinity side of focus, as the calculators want to give that specific 2-3 feet range that will be in focus.

[Sareesh Sudhakaran]

Stopping down and/or using the hyperfocal distance is your best bet. Maybe you might want to look at the GH3 or 5D Mark III, which will give you that extra ISO push for more DOF.

Here's a great resource on understanding DOF: DOF and DOF2

[Jeremy Dallek]

Here's another idea, you can use the EX TELE mode (ETC) in combination with a wider lens. (This mode uses the center 1920x1080 pixels of the sensor) I believe the crop factor is 2.6x for 1080 mode.(3.1x for 720p) So you could take a situation where you would normally use a 35mm lens, put on a 14mm lens, and enable ETC mode. This should give you about the same field of view as the 35mm, but with the depth of field of the 14mm. Of course you can only go as wide as available lenses in the required max aperture allow. If you need F2 or faster about 12mm (31mm ETC equiv) is the widest lens I know of. Or if F4 is fast enough the 7-14mm lens (18-36mm ETC equiv) would be a good option. Just throwing some theories/ideas out there, hope this helps!

[Patrick Janka]

According to this tutorial, sensor size does NOT affect DOF.

DOF Depth Of Field - Photography & Filmmaking Tutorial 15 - YouTube

[James Palanza]

Wow once again a ton of helpful information. Thank you both :)

[Noa Put]

Originally Posted by Patrick Janka

According to this tutorial, sensor size does NOT affect DOF.

Sure about that? A 5DII can provide a shallower dof with the same lens compared to a t2I and there is a reason why you can't achieve the same shallow dof on small sensor camera's. I"d say that sensor size definitely has an impact on the dof.

[Jim Giberti]

Originally Posted by Patrick Janka

According to this tutorial, sensor size does NOT affect DOF.

DOF Depth Of Field - Photography & Filmmaking Tutorial 15 - YouTube

I didn't watch the tute but if that's what it says then it's not accurate.

Sensor size most definitely impacts DOF.
While you can certainly get shallow DOF with a small sensor camera using long lenses, large apertures and proximity, A BMC with will never remotely get the kind of shallow DOF that a full sensor 5D will get with the same lens.

I'm actually amazed that someone would make a tutorial with that. Why does he think that traditional 1/3" sensor video cameras needed spinning glass adapters to achieve shallow DOF?
It's because they have small sensors.

[Jeremy Dallek]

With everything else staying the same, just changing the size of the sensor, or the area of the sensor used, will have no effect on the depth of field. The light that falls on the physical plane of the sensor is exactly the same, just a different crop of the same image. However, to fill the frame/sensor area with the same angle of view, you either need to adjust the distance to the subject, or the optical formula of the lens (use wider lens etc.). Either of these adjustments will change the DOF.

[Bruce Foreman]

Originally Posted by Jim Giberti

I didn't watch the tute but if that's what it says then it's not accurate.

I'm actually amazed that someone would make a tutorial with that.

Because we have "everybody and his brother" making "tutorials" whether or not they have the knowledge/experience to draw from.