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Sony XDCAM PMW-F3 CineAlta
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Old August 14th, 2011, 03:35 AM   #16
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Re: Highly Informative Video on Lens for PMW-F3

I confess I've often done this to lower DOF on an interview but don't feel I've ever noticed it as long as I don't go beyond 1/100 or 1/120. ( I have gone to 1/150) At what point do you feel like you really notice the higher shutter speed? I don't go higher just out of fear not because I've ever noticed a problem.

Eventually I started to carry a set of ND's with me at all times to open the f stop, but no one ever noticed the shutter speed increase or at least said a word to me.

By the same token I often will slow the shutter speed to 1/40 or 1/30 or 1/25 to open up the exposure in low light. Again I've never had a complaint or even noticed a serious problem (even doing steadicam following someone at night.)
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Old August 14th, 2011, 04:55 AM   #17
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Re: Highly Informative Video on Lens for PMW-F3

On an interview you can get away with 1/120, but you do notice the lips sharpening at 1/250.
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Old August 14th, 2011, 09:05 AM   #18
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Re: Highly Informative Video on Lens for PMW-F3

They'd be better off working this way:

1. Back up as far as possible, zoom in as far as possible.

2. Open the iris all the way.

3. Adjust the lights for proper exposure.

Alternately, if it is difficult to bring the lighting down far enough, advance a level of in-camera ND so as to bring the iris back to full open again. Significant shutter speeds just make the video look abnormal.
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Old August 14th, 2011, 09:46 AM   #19
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Re: Highly Informative Video on Lens for PMW-F3

Of course once the camera is already at max distance and longest allowable zoom, the rather large exposure change between the internal ND filters may be too large, so once you've placed gain at -3 the next step is to either add ND filter to the front of the lens, stop the lens down a bit, or tweek the shutter speed. Another issue is that when shooting outside or (indoors with lots of windows) there may be some significant changes in illumination level, and swapping ND's in the middle of an interview or during a standup with a teleprompter may not be an option.
I suppose that's why I wish the cameras had more internal ND filters (to allow the exposure differences to be less far apart) as well as additional negative gains (-6 or even further).
Which begets the question whether with the low noise of the F3 it would make more sense to go with a higher ND level even if it meant going +6 or +9 to maintain exposure? I've found myself at times going +3 after adding ND, but I don't like going past +3 if I can help it...
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Old August 14th, 2011, 10:12 AM   #20
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Re: Highly Informative Video on Lens for PMW-F3

Dave,

I agree with your technique of using heavy ND and then kicking in some gain. The F3 and FS100 are the first cameras I feel that is a legitimate way to shoot. The increase in noise is negligible and the gain pattern is not like the ugly gain of other cameras. However, I would not advise going to -3db. With the F3, you absolutely lose some dynamic range with that setting. I never shoot at -3db with the F3.

If given the choice between losing some of my shallow depth of field or going to a higher shutter speed, I will always sacrifice a little depth of field. Contrary to what has been stated here, even an interview (particulary if you have someone who moves their hands a lot while speaking) will look abnormal if the shutter speed goes above 1/90th. I can see it. Other professionals can see it. And audiences can perceive that something is not quite right. If you want to destroy the cinematic look that you have worked to create, then by all means, shoot with a fast shutter speed.
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Last edited by Doug Jensen; August 14th, 2011 at 10:50 AM.
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Old August 14th, 2011, 12:59 PM   #21
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Re: Highly Informative Video on Lens for PMW-F3

Thanks for that post Doug . I've never noticed it but will stay inside 1/90th in the future. I also was unaware of losing latitude at -3. I do agree with using gain on F3 to adjust for light changes. I also use it in combination with ND settings to sometimes find the right combo to get my iris where I want it. The noiseless qualities of the F3 are very helpful.
AF100 has 3 ND filters which is really an advantage, but the image can't compare.
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Old August 14th, 2011, 02:14 PM   #22
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Re: Highly Informative Video on Lens for PMW-F3

To be honest, I don't use the shutter to control exposure. I tried it a couple of a couple of times and wasn't that happy, I could see the lip effect at !/120 and it was just about acceptable, but there was no other movement on screen.

You can use a fast shutter speed if that's the effect you want, but it's not the standard setting and you're using it as a visual device in it's own right as per "Saving Private Ryan". However, I do find using a high shutter speed on propeller driven aircraft annoying. I've only seen one good use of the effect on an aircraft and that was on an attack helicopter in a feature film, when the blades looked like scimitars.
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Old August 20th, 2011, 09:37 PM   #23
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Re: Highly Informative Video on Lens for PMW-F3

This sounds reminiscent of the HV-20 exposure control "trick"... which is completely incongruous w/ an F3, LOL!
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Old August 21st, 2011, 11:29 AM   #24
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Re: Highly Informative Video on Lens for PMW-F3

Hello All:

First post. . .

I thought it would be helpful to mention that backing away from the subject and using a longer focal length has no effect on depth of field. For any given angle of view, all things being equal, depth of field remains the same. For example, a MCU at 100mm and a MCU at 25mm will have the same depth of field. The perceived focus on the BG may look different because the wider lens will be including more background.

As the focal length of the lens increases and the BG becomes more abstract, the subject appears progressively more of a "floating head" and will have less of sense of place. There are no easy answers as what works in one context may not in another.

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Old August 22nd, 2011, 08:56 AM   #25
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Re: Highly Informative Video on Lens for PMW-F3

Quote:
Originally Posted by Neal Norton
For example, a MCU at 100mm and a MCU at 25mm will have the same depth of field
Doesn't subject distance have an effect on depth of field?
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Old August 22nd, 2011, 12:16 PM   #26
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Re: Highly Informative Video on Lens for PMW-F3

Hi Paul:

Subject distance has an effect on depth of field if the focal length remains the same. For example 50mm at 5 feet has a different depth of field than a 50mm at 50 feet.

If the angle of view is maintained, as an example:

A 50mm lens at 5 meters (3.6 angle of view) at f4 has a 2.06 meter depth of field - 4.17 to 6.23.

A 500mm lens at 50 meters (3.6 angle of view) at f4 has a 1.98 meter depth of field 49 - 51. The .08 difference is rounding error.

That is not to say they look the same. . . only that depth of field is the same.

Many a fine camera assistant has been burned by wide lenses with a close subject to lens distance. . . and the director and/or cameraman can't understand how the AC could 'miss' at 35mm!

Last edited by Neal Norton; August 22nd, 2011 at 12:36 PM. Reason: addding data
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Old August 22nd, 2011, 04:35 PM   #27
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Re: Highly Informative Video on Lens for PMW-F3

Okay - I'll bite... How does a 50mm lens and a 500mm lens have the same angle of view?

(EDIT: okay, I've worked out you mean the width of the view at 5 or 50 meters.)

I realise that changing focal length does not on it's own, change the depth of field. It's a subject that's been confusing a lot of DSLR users who try to work it out for different sized sensors... as if that makes any difference!

Last edited by Paul Ream; August 22nd, 2011 at 05:13 PM.
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Old August 23rd, 2011, 07:47 PM   #28
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Re: Highly Informative Video on Lens for PMW-F3

Quote:
Originally Posted by Doug Jensen View Post
I hope nobody is accusing me of putting someone through the shredder. I just pointed out, for the benefit of those who don't know better, that adjusting shutter speed to change exposure is a bad idea. If that is putting someone through the shredder, then so be it.

BTW, I have been a Sony USA ICE member for 5 years.


Doug,
Raise the shutter high enough and create your own shredder :)
I agree, add ND, or better yet, start with manual iris controllable lens. I have a few Canon EOS lens and it would be great to utilize them (They stay in my 5D kit), but my choice has been Zeiss and Nikkor. I do keep the Sony primes around for the extra 1/2 stop.
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