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EX1 What is Gain -3 all about?

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Frank Manno
EX1 What is Gain -3 all about?
on Dec 23, 2009 at 11:35:45 am

A friend suggested that -3 is the preferred setting for gain where at all possible.

Is this right or should I be shooting at 0db where possible?

In all my cameras over the years I've never heard of gain in the minus range.

What's with the -3 on these cameras?

Thanks! And merry Xmas everyone :)


-Frankie


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Jay Gladwell
Re: EX1 What is Gain -3 all about?
on Dec 23, 2009 at 1:23:13 pm

Read this... http://provideocoalition.com/index.php/aadams/story/no_pain_no_gain/



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Frank Manno
Re: EX1 What is Gain -3 all about?
on Dec 23, 2009 at 2:01:00 pm

Thanks.

I think I best stick to my trusty old 0db then :)


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Bill Ravens
Re: EX1 What is Gain -3 all about?
on Dec 23, 2009 at 2:07:51 pm

The PVC article is only part of the story, where the EX1 is concerned. In reality, for the EX1, there is no appreciable increase in noise at a setting -3dB of gain. However, having said that, it is also important to note that the high-lights are rolled off at a knee that prevents full range images above 90% IRE. In my mind, this is undesirable. My general rule is, if I am shooting an bright, even light, with no specular highlites I need to capture, I will use a gain of -3dB when I need to open the aperture, for whatever reason. Clearly, you'll clip those hilights in any condition of -3dB.



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Jay Gladwell
Re: EX1 What is Gain -3 all about?
on Dec 23, 2009 at 2:38:31 pm

Frank, I think you missed the point of the article.

Like Bill was saying, it's a matter of knowing when to apply such techniques under certain circumstances and why.



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Michael Slowe
Re: EX1 What is Gain -3 all about?
on Dec 23, 2009 at 2:45:54 pm

Wow, that's an eye opener! Ever since I adopted Vortex Media's EX DVD (Doug Jensen) as my 'bible' I followed that and shoot at -3db gain in common with most other people. Never thought about the downside.

Michael Slowe


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Jay Gladwell
Re: EX1 What is Gain -3 all about?
on Dec 23, 2009 at 2:50:14 pm

Mike, Doug didn't simply turn down the gain. He made other adjustments in the PP which have a direct effect on the overall image using the -3 gain setting.

He also stated that under certain circumstances, he did make upward adjustments in the gain.

This all depends on the conditions under which one is shooting on any given occasion.



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Greg Ondera
Re: EX1 What is Gain -3 all about?
on Dec 23, 2009 at 5:23:25 pm

I like the reasoning in the article. I also want to mention Doug Jensen's recommendations of generally using -3db as a best setting in Vortex Media's DVD on the EX1 and EX3: He purports similar reasoning. As for myself, I use -3db as I often use sun-guns on my cameras while shooting surgery, and therefore am likely to get changes in foot-candles when maneuvering the jibs. I often have to use auto iris as well, because I am not able to touch the camera for long periods of time. So if I am in a situation where I am washing the scene out or there are unforgiving hot spots, I want the leverage of being able to fix it in post, and a darker picture is always desirable in that situation. You can't fix an overexposed picture or overexposed spots. So -3db is the best setting, in my mind, for most situations, even without sun-guns, even outside of surgery. Its worked well for me and I advocate listening to Doug Jensen's reasoning as well.

Greg Ondera
http://www.Plexus.tv
http://www.SurgeonToday.org


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Greg Ondera
Re: EX1 What is Gain -3 all about?
on Dec 23, 2009 at 5:38:23 pm

Once again, I responded to a post without reading the last two posts. I want to apologize. I would like to hear some of your reasoning applied to using sun-guns in movable camera situations as well?

Greg Ondera
http://www.Plexus.tv
http://www.SurgeonToday.org


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Jim McNally
Re: EX1 What is Gain -3 all about?
on Dec 24, 2009 at 7:33:36 am

I haven't had too much problem with blowing out highlites but my preference is -3 so that I open up the aperture which helps to decrease the depth of field.

Jim McNally
The Commercial Factory
http://www.commercialfactory.com


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Alister Chapman
Re: EX1 What is Gain -3 all about?
on Jan 10, 2010 at 7:45:03 pm

With most video camera you only get the full dynamic range at 0db. Using -3db normally also means a reduction in dynamic range by around 1 stop. Now on the EX, as has already been mentioned at -3db the white clip is also reduced by 3db to around 92IRE with the standard gammas. Because of this I would strongly recommend not using -3db gain unless essential or you have good control over your lighting. If you are dealing with spot lights and difficult lighting -3db gain is going to have a big negative impact on when your highlights blow out.

It's not quite so bad if your using the cinegammas as these record up to 109 at 0db which drops to 104 at -3db. Much will depend on how you deliver your video as to whether whites above 100 will be clipped off or not.

Alister Chapman
http://www.xdcam-user.com


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Rafael Amador
Re: EX1 What is Gain -3 all about?
on Jan 11, 2010 at 3:41:20 am

For the people that uses Doug's PP, It would be good to watch again the Vortex DVD and pay some attention to the lighting conditions of the clips hi shows (and how the picture noise rise when is applied).
His PP may works very well in exteriors in his local area. It doesn't in mine.
I wonder if Doug is still using the same PP, but I'm sure hi wouldn't recommend it for something like Chroma Key or surgery video.
About the "-3db" gain, I think that the Video Coalition article gives very good reasons to be very selective on using it.
Cheers,
rafael



http://www.nagavideo.com


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