Deliberately under-expose in well lit conditions?

fausseplanete wrote on 11/26/2008, 8:53 PM

As Serena suggested, I have started a new thread for this topic, which originally I extended into from the tail of the one at [http://www.sonycreativesoftware.com/forums/ShowMessage.asp?MessageID=625797&Replies=27]. For "catch up" purposes, I have pasted the text of the replies so far once again, below.

Underexposing to avoid "video look" I am not so sure about. I used to do that with my Z1, to avoid "video" look e.g. room lights not saturated blobs, then boost using S-curves. But then found I needed some kind of denoising software again, which is CPU-intensive. I wonder if the advisability of this depends on the signal/noise ratio in the camera, in which case maybe only advisable for higher-end cameras or at least better s/n (maybe the EX's ?). Any opinions on this?

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Subject: RE: Gain - in camera or in post
Reply by: tumbleweed2
Date: 11/26/2008 4:44:13 PM

I'm no expert, but in the old analog days, it was common for a broadcast quality cam to have a S/N ratio of 62db or higher, where as todays prosumer & lower end professional units seem to be touting 54db levels, the EX1 for example... & I'm pretty sure your Z1 has a 54db level...

My reasoning for underexposing some was to not lose all the detail in the highlights & still be able to bring up my blacks to show some detail that is there....
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Subject: RE: Gain - in camera or in post
Reply by: Serena
Date: 11/26/2008 9:55:12 PM

"My reasoning for underexposing some was to not lose all the detail in the highlights"

Yes, that is fine but not always achievable within the dynamic range of 8 bits. However that isn't the problem explored in this thread. You need to go back to the top and read the question and the first few responses. Would be better to start a new thread if you want to discuss the general question of how to optimise exposure under well lit conditions.

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Comments

Jay Gladwell wrote on 11/28/2008, 3:27 AM

Grazie, it's been so long ago, my memory has totally failed me. I don't even remember where I saw/found the videos.

<sihg> "A mind is a terrible thing to waste."

Jay Gladwell wrote on 11/28/2008, 3:40 AM

David, remember I did say there was always the exception to the rule.

And I think the videos do fit within the thread. One should have a target to aim for, regardless of the circumstances.

Using your example, I had to shoot a young woman--a singer--performing under a large canopy. No big deal, huh? Well, she was an Afro-Amercian with what I would refer to as a medium-dark complexion. It was a blazingly bright sunny day here in Miami, and the sun was falling directly on the backgound behind her. As soon as I saw the situation, I let the client know what was going to happen visually.

I explained that if I exposed for her the background would go white. If I exposed anywhere near for the background she would go into silhouette. I had no choice but to let the background get totally blown out. To compensate, I shot her in a very tight close-up to minimize the bright white background.

So there are exceptions--no absolutes.

Serena wrote on 11/28/2008, 4:05 AM

>>>>When you say "skin" what type of skin are you referring to? Not all skin reflects light the same. The obvious example is the difference between the skin of a Caucasian and that of a Black African<<<

I think that demonstrates very well that some people don't bother reading the argument before refuting it. In any case it's an odd response. Did I say 'between 59% and 61%'? Not in the usual interpretation of numbers. But just to clarify for you, several people have observed that setting 60% on the zebras rather than 70% produces better rendering of Caucasian skin (there, I've said it again for you). Really a waste of time.

Grazie wrote on 11/28/2008, 4:12 AM

Jay I had almost exact same situ.

I had a dark skinned woman, against a white - important this! - truck with the name of the organization on it. I could expose for the woman OR the truck. Not both. So I had my partner hold a reflector very close to the woman and stopped down to get the truck with SOME sharp legible text detail appearing behind and over her shoulders. I also ND-ed down with a pola and whistled God Save the Queen! It worked. The woman looked great with her great smile and her gold jewelery. Added to which what she was talking about was reflected on the trucks sides.

So, if possible, ND for natural stops and keeping the iris open for shallow DoF; a pola for some extra dynamic detail and glare-off and finally pull a nice reflector to bounce-up onto the jewellery and face.

But yes, it is often when things are out of our control, wither to expose for the brights or expose for the darks and be done with it. But these conversations almost always hang on the actual level of each and knowing KNOWING just what is the important reference for the edit.

It has been known for me to have a setup shot without the talent and exposed as I want; place the talent and then mask around? But don't tell anybody! Lol!!

Grazie

Jay Gladwell wrote on 11/28/2008, 4:54 AM

Serena, get off your high horse and say what you mean. That way there is no room for misunderstanding.

You're "clarifying" statement would suggest that everyone being videotaped is Caucasian. Such is not the case.

farss wrote on 11/28/2008, 4:59 AM

[I]"It has been known for me to have a setup shot without the talent and exposed as I want; place the talent and then mask around? But don't tell anybody! Lol!!"[/i]

Shoot a correctly exposed background.
Shoot it blown out with correct exposure for the talent when they're in the shot.
Use a difference mask to extract the talent. Composite onto the correctly exposed background.

Pray nothing moves a pixel between shots that shouldn't. Hope that lighting stays constant etc.
Even if it works HDR images can look really wierd.

If you have the kit a large black scrim can save the day. Think of it as a monster ND to be put between the talent and the background. They're used a lot in OBs behind the talking heads at sporting events. With care they can even help throw the background out of focus as well.

Don't need to spend a lot of money to get one either. Black shade cloth stretched onto a frame of PVC pipe will do.

Bob.

Grazie wrote on 11/28/2008, 7:04 AM

Here, "Difference" was NOT an option. But in other setups - yes, sure. Not with all the comings and goings of London industrial estate, loadsa unfortunate shadows . . the subject kept fluffing lines and the Sun was moving around. I did what I did and made the poor woman do more than 3 takes . . . This allowed me to cut INs and OUOTs and closeups. Plenty of B-roll!

The Scrim thingie is great. But again, I can now see that that would not have been a solution.

Grazie

Serena wrote on 11/28/2008, 2:27 PM

>>>>Serena, get off your high horse and say what you mean.<<<

Jay, I think that wouldn't be considered polite. Actually no horses are involved. Guess I should have been more expansive in making my points, but I expected that a few pointers would be sufficient (the post was large as it was). If I intended "skin" to mean all skin, I wouldn't have specified Caucasian, and as with all such pointers one expects the reader to evaluate the information and consider how it might apply in other situations. We expect experienced people to respond on points of disagreement with information. In this case you might have said how the suggested 60% (55-65) is not what you find (class specified) and added useful information about dark skin types. The actual figure was less important than the matter mentioned: "apricot plastic looking skin highlights". I value greatly exchanges of experience, but your heckling type of response doesn't contribute anything of value.

Patryk Rebisz wrote on 11/28/2008, 3:11 PM

Jay, actually i agree with Glenn's point of view ("Clipping is ok if the image looks better") because it all depends on the frame.

Take this example (old project i shot):

when i have the people back-lit i over expose inconsequential details freewilly however when i have the people lit frontally (or from the side) i close down the iris (sometimes with quite unattractive results when you see really nothing else but the "properly-exposed-it-seems" person - see the guy in the glasses half-way through the video)

Also you statement about eye going to the brightest point isn't totally correct. The brightest spot is used as psychological reference -- the eye find the brightest and darkest spot and reads it as the brightness-to-darkness range. Thus you can actually have the subject underexposed (young girl at the beginning) as long as you retain a bright spot in the frame (blurry foliage in the bg) thus telling the eye ("look i'm giving you a whole range of values").

Also just to clarify something another poster said:
1 stop of difference is HUGE - it means you need 1x less (or more) light. So 2 stop difference means you will need 4x less (or more) of the light.

Jay Gladwell wrote on 11/28/2008, 3:38 PM

Got this link from Bill Ravens in another forum. Some might find it interesting.

Serena wrote on 11/28/2008, 4:34 PM

Patryk, a lot of good examples in that clip that demonstrate your point. A great deal depends on context. In a vox populi the viewer's expectations are lower than of, for example, fashion shots. I see also examples of the "apricot plastic" skin highlights (e.g. 2.20 to 2.40) which in the past I've spent a lot of time trying to meliorate (but not a problem in the context of the clip).

Grazie wrote on 11/28/2008, 11:35 PM

Patryk, I enjoyed your work. I was watching your framing and content positioning PLUS your use of BG lights and dark areas. I watch this kind of work with the audio OFF - it allows me to concentrate on the camera's operating methodology. It's almost like reading a musical score, and appreciating just what the scale of work and craftsmanship goes into it.

Nice job! - I learnt loads. Seeing this and seeing some of my cherished BBC output - some of the Corporation's "hired-hands" have much to learn, IMO!

Just a small "Grazie-deviation" here, but what did you use for that shallow DoF? A device? Camera settings? What? Am I seeing the use of a reflector?

Grazie

Serena wrote on 11/29/2008, 4:24 AM

Indeed. While watching I was observing that the "defects" being illustrated were insignificant because the images had impact. In normal viewing I doubt that I would have noticed those matters..