cinematography How to get rid of infinite depth video look...

chokingthealligator

chokingthealligator

Hey guys I'm trying to create a 'film look' shooting 25f on the Canon HXA1. I can't figure out how to get rid of that indefinite depth of focus that video has and focus just on my subject with the background slightly blurry, like in film.

Does anyone know how to do this? I've changed to manual focus but that just lets me drift in and out focus rather than changing the depth of focus if you get me?

Thanks guys :)
 
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chokingthealligator said:
Hey guys I'm trying to create a 'film look' shooting 25f on the Canon HXA1. I can't figure out how to get rid of that indefinite depth of focus that video has and focus just on my subject with the background slightly blurry, like in film.

Does anyone know how to do this? I've changed to manual focus but that just lets me drift in and out focus rather than changing the depth of focus if you get me?

Thanks guys :)
Click to expand...

On that camera you'll want some sort of ground glass adapter like a Red Rock, Letus, Brevis, P+S Teknik, and so on. Search around here for things like "depth of field" and the product names above.

Also this might help you understand the mechanics of what you seek:

http://en.wikipedia.org/wiki/Depth_of_field

Nice camera, but with 1/3" CCDs you are going to be working with a very wide DoF without going with some sort of adapter/still lens setup.
 
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Oooh right so I would actually need to purchase extra equipment! (I'm just doing a student film) so is there no way to alter the DOP with just the settings some bloke mentioned messing with the 'iris' but this just seemed to change the light levels...
 
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You can place the camera far away from your subject, and your subject as far as you can from the background. Then zoom in on the subject to frame your shot and use the manual focus to focus on the subject.

Voila! Shallow depth of field. The farther away your camera is from your subject and your subject is from the background, the shallower the depth of field.

Hope that helps. :)
 
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I really can't recommend strongly enough that you read the wiki I linked.

DoF is an interaction between 4 primary factors:

Image plane size (ie sensor format, film format, etc).
Focal Length of the lens.
The f-stop at which you are shooting.
Distance from focal plane to image subject.

At a 1/3" sensor size, changes in f-stop are not going to alter your DoF considerably.

You MIGHT be able to go to the long end of the lens, wide open (lowest f-stop) and get a somewhat shallow field. Of course then you are very limited in camera placement because you need to move back in order to get the frame you want. There is a problem with that approach:

DoF INCREASES as you move farther from the lens. Changes in distance from lens to subject will change DoF FASTER than changes in focal length. Therefore even when you "zoom all the way in" you have to move back farther, which cancels out some of your approach towards a shallow DoF. This also means that you have to create artificial separation between the subject and their background which cannot always be done at location.

There's no need to buy them. Look around for someone with an adapter and a lens kit that might cut you a break for a student rental. You might even land one in trade for some favor or service, or even just for free.

Test it out. Find a frame you like with the lens zoomed all the way in and wide open and see if it is as shallow as you want. My gut feeling though is that A: it won't be quite what you seek, and B: the framing and camera placement will be very very limiting and make your shoot more difficult.

Dreadylocks said:
Voila! Shallow depth of field. The farther away your camera is from your subject and your subject is from the background, the shallower the depth of field.
Click to expand...

I'm sorry, but that is only partially true. The distance in your equation is just a side effect to get the frame you need at the long end of the lens. Additionally, being able to physically separate the subject from the background is not always practical on the day. It's not a big deal to recommend people do this, but it should come with a caveat because it leads some people to understand the relationship between subject distance and DoF in reverse. I can't seem to repeat this enough around here: DoF INCREASES when the subject is farther from the lens and DECREASES when the subject is closer. It's a mathematical certainty. :D The need to compensate by placing the subject farther from their background demonstrates this.

Sorry for being a stickler on this, but there's some fundamental science here that I think anyone asking this question should at least attempt to understand at a basic level before trying to "trick" things into place. :D
 
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David.rhsc said:
I really can't recommend strongly enough that you read the wiki I linked.

DoF is an interaction between 4 primary factors:

Image plane size (ie sensor format, film format, etc).
Focal Length of the lens.
The f-stop at which you are shooting.
Distance from focal plane to image subject.

…

Sorry for being a stickler on this, but there's some fundamental science here that I think anyone asking this question should at least attempt to understand at a basic level before trying to "trick" things into place. :D
Click to expand...

I am going to be incredibly pedantic and point out that the size of the image plane arguably doesn't affect the depth of field - a larger sensor just forces you to use longer lenses to achieve the same FOV, which gives you a shallower depth of field.

*runs*
 
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chilipie said:
I am going to be incredibly pedantic and point out that the size of the image plane arguably doesn't affect the depth of field - a larger sensor just forces you to use longer lenses to achieve the same FOV, which gives you a shallower depth of field.

*runs*
Click to expand...

HeeHee

https://www.youtube.com/watch?v=QguWdSsI8S8
 
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chilipie said:
I am going to be incredibly pedantic and point out that the size of the image plane arguably doesn't affect the depth of field - a larger sensor just forces you to use longer lenses to achieve the same FOV, which gives you a shallower depth of field.

*runs*
Click to expand...

Technically true, no need to run. :lol:

Mathematically it doesn't fit into the equation, but because you have to make alterations to the variables in order to achieve the same field of view between different formats there is a practical difference that is good to understand at a fundamental level. For a given FoV measurable in degrees with subject distance and f-stop unchanged, DoF will be wider on a smaller format sensor. (How's that for pedantic! :lol:)

Which is tangentially why I am similarly incredibly pedantic about subject distance. ;) If someone who doesn't understand the relationship between distance and DoF tries to pull focus for an object coming into or away from the lens on axis is going to be sort of flustered. :D On a practical level, yeah it can be sort of cheated. But when the cheat doesn't work or parameters change or the conditions of the location dictate the cheat cannot be used, then having the knowledge to solve the problem becomes important.
 
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