How to shoot to get more depth of field
 

Gurus,

Last week I was shooting using XL2 and 2 Lowell Total lights with 750 halogen bulb on each. I was bouncing the light off the ceiling to get more diffused light rather than harsh light. First time I tried shooting using aperture mode. I was surprised to see that i could shoot only at 2.8. If I shoot at f stop of say 4 I had to use video gain of I think 6 or so...

I would like to shoot at 5.6 or so to get more depth of field. My problem is that when I shoot on auto, I am loosing focus on a slight movement (which is on auto because I shooting dance).

What are my options to shoot on auto and using auot focus?
What are my options to shoot in aperture priority and using auto focus?


Any ideas?

auto on both focus and exposure is a kind of get you out of trouble, last ditch attempt at getting a picture when you can't do it yourself.

manual exposure control is always better than auto. you expose correctly the subject and unless the light levels change greatly, all is well. Auto ramps up and down at the hint of a low or highlight in the shot. Auto focus - not much I can say apart from switch the damn thing off. at best, they are nearly ok - at worst, they hunt - especially when it is dark, and some colours, red being one, always seem to confuse them. Your eyes can set aperture and focus much better, and often quicker. Some cameras do make manual adjustment quite tricky as they don't directly control the focus/aperture mechanically, but via a servos, which always has a bit of lag and overshoot.

Your original question was to achieve greater depth of field. To do this you simply need to operate with the lense on a smaller f number, but to do this you need bags of light, or close in equipment, or both. closing the iris without increasing light may well require turning the gain up. Not a lot you can do about this - just physics. Don't forget the inverse square law is involved here. Bouncing your lights off the ceiling may well double the distance the light has to travel, which results not in half the light level, but a quarter! Equally you can take advantage of the same rule - moving the lights in from 4m to 2m doesn't double the light level, it quadruples it!

Thank you for response...
You are right about f-stop and light thing...Last time I did use gain...

Bouncing...yes...it did waste much of the light...Direct lights were too harsh...I tried umbrella but again the light output was too little...One thing we have not tried is putting the lights as close as possible and bounce...I will try that this saturday.

Now the question is:
In the view finder it is kind of hard to make sure that the things are in focus...Also, often I shoot on shoulder. Means I can not have bulky monitor..
I am also using on-camera light NRG (150 V AC)..I have assistant following me with cables..

Do I need to practice to understand the focus using viewfinder? Or you guys always use monitor...If you do, what do you do when you shoot on shoulder?

If you turn up the stock EVF's sharpness setting all the way (it's centered by default) in the display menu, focusing with it is MUCH easier--not quite perfect, but mostly doable. It's actually a really big improvement over the default setting. You just have to keep in mind while shooting that your edges are not quite as oversharp as they appear in the EVF.

This is basically a "lite" version of the peaking feature found on many HDV cams. It's a little trick I don't see mentioned very often. I've had much more luck with focusing the stock lens since I changed this setting.

why do you need more depth of field...are you shooting with a really long lens or something very close? I always find the opposite problem..digital video always has too much dof for me. And I dont think the difference between a few stops is going to make a noticable difference anyway. I mean, I only notice a siginficant diferrence dof on my camera (gs400) if I change by about 6 or more stops at the least.

That's a good tip, Jarrod. In connection with that, I try to make sure that my highlights in the scene give a bit of zebra at 90. When you see the zebras, you can set your focus by 'maximizing' the zebra pattern. As you go out of focus and scatter the light rays, the zebras will disappear.

-gb-

See also The Ultimate Depth-of-Field Skinny at http://www.dvinfo.net/articles/optics/dofskinny.php

Good tips guys. thanks.

Richard

In 1/3" CCD world you need to use the lens LONG (zoomed 8X or more) leave the aperature WIDE OPEN and control the light with ND filters.



ash =o)

Ash--

Vipul is trying to maximixe DOF, not minimize it. I suspect that you may have misinterpreted his post and thought I'd point this out in case someone out there is trying these suggestions and scratching their heads when their backgrounds are out of focus. :)

LOL... Rarely hear people trying to get MORE depth out of a 1/3" CCD camera.



ash =o)

I agree Ash...

See..I am shooting Indian wedding and reception. In weddings (not much movement of subjects) I don't need DOF and I can focus nicely especially after applying the tips I got from the repsonses (increased sharpness of EVF, not shooting on Auto mode etc)..

By in reception we have lots of performances..And believe me or not these people (usally group of 5 -15 people) dance on dance floor...Very rapid movements..not standing at one spot for a second..This where I need more DOF...

Hope it helps...

Jarrod...OK, now I'm confused. I always thought that when the background is out of focus and the foreground (a person talking, for example) is in focus, then you have a greater (max.) DoF...meaning the camera is far away from the background, zoomed in on the subject? That's the composition you want if there's a too much going on in the background and you want the audience/viewer to "focus" on the person talking, right?

Jonathan

Jonathan,

It's other way around....if background is also in focus in addition to the people taking in foreground ==> greate DOF..This usually you achieve by having higher f-stop (iris/ aperture) on a given lens.

Gotcha. Thanks, Vipul.