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Old January 31st, 2009, 07:24 AM   #1
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Use neutral density filters to control DOF with 5DmkII

This is the most basic way to control any video camera, a pro vid cam always has built in ND's.

Shooting outside during the day you pretty much always use them.

The 5d mkII is a still camera, and if you want to use it as a video cam then get some ND filters.

I find with ND filters I can get the look I am after with Canon lenses. It just takes some experimenting. Using the exposure lock pointing at the same area will give you repeatable results. To get less DPF add more ND. I use a #9 (3 stops) most of the time and a #6 (2 stops) in the shade, in very bright light use both, that is a 5 stop difference.

I would love to get complete manual control, but this is a great start.
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Old January 31st, 2009, 08:10 AM   #2
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you are correct... and for a fantastic solution use the singh ray vari-nd filter which will allow you to dial in form 2-8 stops with just one filter....
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Old February 2nd, 2009, 10:01 AM   #3
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yeah but that won't affect DOF... I have used NDs to allow me to keep my lens wide open. As far as I can technically tell you're dimming the glass rather than shrinking the glass... (rear element).
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Old February 2nd, 2009, 10:10 AM   #4
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uhhh.... less light into the front of lens = faster ( more open ) aperture = shallower depth of field.... ( but only as shallow as the lens it's self is capable of )
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Old February 2nd, 2009, 10:18 AM   #5
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I always thought that DOF was a direct function of the size of the back glass... the mechanical closing down of that glass increases focus range and decreases light sensitivity...

I'm under the impression that the mechanics affect the DOF not the light itself.

If light=dof, in dim conditions a fast lens wouldn't be fast...?

Here's a link to another thread:
http://www.dvinfo.net/conf/hdv2-cano...lters-dof.html
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Old February 2nd, 2009, 11:35 AM   #6
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Originally Posted by Josh Brusin View Post
I always thought that DOF was a direct function of the size of the back glass... the mechanical closing down of that glass increases focus range and decreases light sensitivity...

I'm under the impression that the mechanics affect the DOF not the light itself.

If light=dof, in dim conditions a fast lens wouldn't be fast...?

Here's a link to another thread:
http://www.dvinfo.net/conf/hdv2-cano...lters-dof.html
Uh, true it's not the light itself that controls depth of field, but the ND will cut light out and allow you to open your aperture more. For example, say you're outside on a sunny day and you want to open you aperture real wide for a shallow depth of field result. To do that, in all likelihood, you'll have to have your shutter running super fast like 1/2000 to 1/8000. Wel in video, that shutter speed (if it's even possible to obtain), will look like crap. Adding an ND4 will allow you to keep that same aperture and bring the speed way, way down. This of course is complicated by the auto-everything mode of the 5D2, but given that, it's even more important because adding the ND will permit you to use some of the other "tricks" to get the aperture and ISO where you want them for this type of sunny shot (low iso, open aperture). Without the ND in this situation, it'd be impossible to do (at least impossible without ridiculous shutter speeds).

This is pretty straightforward stuff, or am I missing something here?

Yes, ND = good. If you own a 5D2 and shoot video anywhere outside, you need them if you want shallow depth of field, period.
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Old February 2nd, 2009, 11:42 AM   #7
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I concur with Bill

And shooting filmic video requires a slower shutter speed ( 1/30, 1/45, 1/60 ) to give the right look.... and as the 5d2 will only go down to iso100 in vid, it will take quite a few stops of ND to get a wide to medium field of view lens to have a wide aperture in bright light.
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Old February 2nd, 2009, 12:07 PM   #8
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Yes, I have a full set of ND filters and polarizers. Any pro looking to control their image in differing lights is versed in their use. We use them all the time - with shutter, aperture and ISO, not as a replacement for them.

You can uncouple your state-of-the-art "L" lenses too - but neither approach is a replacement for basic controls available on the most inexpensive cameras.

This is a wonderful, high end, 21st century camera and the discussions should be about how to get the best quality images from it. Instead, most threads around the internet are focused on how to work around the lack of the most basic functions to get workable image shot to shot.
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Old February 2nd, 2009, 04:56 PM   #9
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Originally Posted by Bill Binder View Post
Uh, true it's not the light itself that controls depth of field, but the ND will cut light out and allow you to open your aperture more. For example, say you're outside on a sunny day and you want to open you aperture real wide for a shallow depth of field result. To do that, in all likelihood, you'll have to have your shutter running super fast like 1/2000 to 1/8000. Wel in video, that shutter speed (if it's even possible to obtain), will look like crap. Adding an ND4 will allow you to keep that same aperture and bring the speed way, way down. This of course is complicated by the auto-everything mode of the 5D2, but given that, it's even more important because adding the ND will permit you to use some of the other "tricks" to get the aperture and ISO where you want them for this type of sunny shot (low iso, open aperture). Without the ND in this situation, it'd be impossible to do (at least impossible without ridiculous shutter speeds).

This is pretty straightforward stuff, or am I missing something here?

Yes, ND = good. If you own a 5D2 and shoot video anywhere outside, you need them if you want shallow depth of field, period.
You're not missing anything. I think we're all in agreement that a ND filter itself will not affect your DOF and that if you want to be able to shoot with a wide open aperture, say in brighter conditions, to maximize shallow depth then you should use the ND.

I guess I misunderstood the original post. I thought what was implied was that the ND filter itself would affect the DOF... I just wanted to clarify that a lens open at say 1.4 will have the same DOF with or without the NDs.
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Old May 28th, 2010, 06:45 PM   #10
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Originally Posted by Christopher Witz View Post
you are correct... and for a fantastic solution use the singh ray vari-nd filter which will allow you to dial in form 2-8 stops with just one filter....
Christopher,

That's a nice piece of kit, but what if you have a set of prime lenses with a multitude of thread mounts?

Best option I thought possible was to buy a matte box and a set of ND filters. It's a more future-proof option.

However... nice if you only ever intend to have the one lens, or all canon lenses with 77mm thread.
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Old May 28th, 2010, 07:04 PM   #11
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Old May 29th, 2010, 09:53 AM   #12
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The big problem with a mattebox is that most vignette to some degree with lenses wider than 24mm. I use lenses a lot wider than this for a lot of my work, and is one reason why I rarely use them with the 5D.
Even though I have a selection of neutral NDs, I prefer to use PL filters. My ND grads get more use than the plain ND filters.
I do own step-down rings, but they rarely get much use nowadays because it is much quicker and less hassle to have a selection of seperate filters for each lens. For example, a PL filter is generally fitted to all the lenses in my bags, and only removed during low light levels or night-shooting. An extra ND is added in extreme bright midday sunshine if I need to lower shutter speed but maintain set aperture.
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Old May 29th, 2010, 05:40 PM   #13
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For some reason, reading this thread as it exists is confusing.

It's probably either that the original conversation had people confusing terms - or perhaps just because the information was parceled out so slowly, that the critical point got kinda diffused.

So, in the interests of the beginners to DSLR shooting who are after a shallow depth of field - I'm going to try to make it crystal clear. (wish me luck.)

Due to the unrelenting rules of physics, the factor that determines the depth of field on any photographic system is the SIZE of the APERTURE set on the camera doing the shooting. Period. End of story.

For those who haven't studied cameras much, the aperture is the SIZE of the HOLE that lets the light coming through the lens hit the camera's light sensor. On nearly ALL modern cameras, the aperture (AKA "iris" on some cameras) is VARIABLE as to size, typically composed of a series of curved mechanical blades that open up (or close down) the size of the opening as needed.

The REASON any OTHER action (adding ND filters, lowering lights on the set, owning a "slower" lens, pushing in for a longer zoom setting, etc.) has an effect on the depth of field is that in doing ANY of these - you're lowering the amount of light passing through the lens and THEREFORE forcing the Aperture to OPEN UP in order to properly expose the shot. That's it. It's NEVER the "Act" of adding the filter - but rather the filters EFFECT on camera APERTURE setting that changes the depth of field.

One final thing can help you understand this stuff in the era of DSLRs.

For decades, video chips were small. 1/3 of an inch was common. The geometry of lens design makes it a fact of life that the SMALLER the surface of the receiving sensor, the HARDER it is to achieve a wide aperture and therefore get the small depth of field everyone seems to relish so much these days.

So nobody worried about it. Only FILM cameras - with their big old 35mm frames - could achieve nice shallow depths of field.

Then came the 5dMkii - and suddenly, there was an affordable VIDEO sensor with the same (actually BETTER!) sensor geometry than the 35mm movie camera.

So depth of field manipulation is back - big time.

But the essential truth is to push your depth of field to be more shallow - you have to OPEN UP your aperture.

End of story.

Hope that helps keep things clear.
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Old May 29th, 2010, 06:33 PM   #14
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I think most people reading these forums understand that ND filters in themselves do not affect depth of field.

DOF can only be controlled by adjusting the size of the lens aperture (apart from adjusting optics angle to subject such as when using a shift lens).

So in far simpler terms... open up the aperture to obtain narrow DOF, close down the aperture to obtain wider DOF.

During very bright conditions, to maintain a set shutter speed without having to close aperture too much (or visa versa where you want to keep a set aperture without needing to up shutter speed too much), simply use ND filter/s (or PL filter if you prefer).

Try to also remember that both film & video cannot cope with dramatic light differences within the same scene (such as background subject in full sunlight and foreground in shadow). A straight shot or video clip of such a scene, even when normal ND filters are used, will not correctly expose both shadows and highlights. To expose the entire scene correctly with details in both foreground and background, a Graduated ND filter needs to be placed in front of the lens.
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Old June 5th, 2010, 01:05 AM   #15
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Just to throw it out if someone is interested, there are 2 RedCentre podcasts that are great for breaking down different ND filter qualities and also taking into consideration how infrared effects the sensors of cameras as you ND up. The infrared one is #62 and the other slipped into the fxguide video podcast but includes variable NDs - its #74.

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