White Balance

[Graeme Nattress]

Yes, gaining down will increase quantisation noise, and could therefore decrease quality.

Graeme

 

[martinnoweck]

Thanks Graeme, good to know!

 

[Graeme Nattress]

Ideally, you want the expsosure to fill as much of the 0-4095 12bit a-to-d range as possible, without clipping, to record the most information from the scene. When the dynamic range is greater than that recordable, you've got to then decide which part of the tonal range is most important and expose accordingly, but that's the same for both film and digital.

Graeme

 

[Steve Gibby]

Whether you use screw-on or clamp-on filters or rectangular filters in a clip-on mattebox, you'll want to use ND filters outdoors, and probably a sunshade. Filters that can be dropped in a filter tray slot tend to be faster to switch between than screw-on filters.

The use of ND filters is almost always necessary when shooting outdoors, whether it’s in a cine-style or EFP style workflow. Timothy wanted to know if him using a matte box on his 2/3” HD lenses was mandatory, which it isn’t, but as I indicated, he would still need to use screw on filters. If he already has screw on filters for his 2/3” HD lens, or he has access to some, can’t afford a matte box, or a matte box won’t fit in the spaces he’s working in for an EFP workflow, then screw on filters are an option. You correctly noted that drop in filters are faster, but I did suggest to him in my post #55 that if he needs to use a matte box that a lightweight clip on matte box would be the best for his mobile EFP workflow.

Just remember that in direct sunlight at 50 ASA on a clear day, at 24 fps with a 1/48 shutter, the exposure is usually around f/16.

In the EFP workflow that Timothy uses on his DXC-637, he uses zebras and a +6/9/18 DB gain toggle switch to set exposure. Obviously setting exposure on RED one will be a learning experience for him, but though RED One is a manually operated camera, it’s an electronic camera with a close pedigree to DSLR cameras. Since Timothy is an EFP user, I’d say that he won’t be using a hand held light meter as some RED adopters from the traditional film industry will still choose to do with RED One. Getting to proper exposure is the point. He’ll probably be using the exposure tools that RED has developed for the RED One camera: an interactive histogram and a waveform monitor that are viewable on the EVF or LCD, either full view, or in scaled down version in the periphery of the frame. Again an indication of RED One’s pedigree: histogram use with CMOS sensors, and shooting RAW is pervasive throughout the DSLR industry – not the video industry, and certainly not the film industry. The use and feature set of RED One’s exposure tools were not fully unveiled at NAB, but here’s a simple explanation by Graeme of exposure with RED one:

“1) shoot RAW. That makes digital cinema a lot more easy to use.

2) expose correctly. Expose to the right - just like you do with a DSLR.

3) SNR = Dynamic range. You place the white clipping point where you want it, and let the shadows fall where they fall.”

Graeme
11/20/06
DVX
http://www.dvxuser.com/V6/showthread.php?t=78640

Once RED fully unveils the exposure tools incorporated in RED One we can evaluate them. IMO nobody is going to have to use a hand held light meter with RED One to achieve accurate exposure. They may choose to because that is their comfort zone workflow, which is fine, but they won’t have to if RED One’s exposure tools can get the job done quickly and accurately. I’ll have one of the first shipping RED One cameras and it will be tested extensively, including the exposure controls, thus we should have some real world answers soon.

And the RED camera is more like a 250 to 320 ASA camera, as are many video cameras, which is why pro ENG cameras have heavy ND filters in the internal filter wheel. It's not unusual to have four or six stops worth of ND filtration on a sunny day if you want to reduce depth of field to something manageable, but as soon as the light drops or you move into shade, you need to be able to quickly swap filters.

Timothy mentioned that he has been using a DXC-637 BetaCam SP camcorder, a camera I am familiar with and used some time ago. As such he knows that pro ENG cameras have filter wheels, because his 637 does. As I remember, the DXC-637 has a 4-filter internal wheel:

#1 – 3200k
#2 – 5600k + 1/16ND
#3 – 5600k + 1/8ND
#4 – 5600K + 1/4ND

The DXC-637 has auto-iris capability, which is switched by a slider switch on the lens servo, by the rocker switch. It also has a manual position for iris. Zebra is available, and probably used by Timothy to help achieve correct exposure.

White balance on the DXC-637 is via a 3-position switch: A and B manual WB, and an Auto WB setting.

When I use an ENG camera, and I’m rapidly going from interior to exterior lighting, I’ll either do a quick manual WB on two different filters (1 for interior, 2/3/ or 4 for exterior), and switch between them as I move between lighting environments, or if it is unfeasible to switch because of time constraints or multiple environments, then use the auto WB.

For rapid movement from indoor to outdoor lighting with RED One, Timothy won’t have the filter wheel he is used to, so he’ll need to use the RED One histogram and manually screw on or drop in filters on the fly – something that will take getting used to for him. In cases like that, a lightweight snap-on matte box, like I previously suggested to him in my post #55, and drop in filters would be the fastest method. If he has more time and can re-setup the rig, then screw in filters, and a sun shade (naturally), would be workable.


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As Graeme just mentioned in his post #80, he believes RED One will have selectable ISO rating (or maybe the equivalent, I’d say), thus another indication of RED One’s close pedigree to DSLR use. In his post #82 he then warns about the effects of gaining down on image quality.

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In my post #61 I summarized for Timothy the difference in front-end approaches when shooting RAW vs. RGB – values baked in with RGB, but flexible with RAW. I think the cool thing with a RED/RAW/REDCINE workflow is the flexibility at the acquisition stage, and the ability tweak the footage in REDCINE: de-mosaic, profile, white balance, grading, colormetry. That workflow will be very familiar to those of use who also shoot DSLR RAW and process RAW with software tools. It will not be familiar to TV/video shooters and editors, and definitely not be familiar to traditional film shooters. I’ve been immersed in all three mediums (video, film, DSLR), and I sincerely welcome the DSLR-like acquisition and processing workflow of RED One/RAW/REDCINE. That’s not to say it’s identical by any means. A motion camera is a different animal than a stills camera.

When I work as a cinematographer, I’m used to nailing down the values and parameters of the image at the acquisition stage. When I work as a videographer I’m used to nailing down most of the values at the acquisition stage, but also having reasonable opportunity to salvage slightly over/under values in post. When I work as a still photographer in a DSLR workflow, shooting RAW, I’m used to nailing down certain exact values (focus, etc.), but with RAW having the non-baked in flexibility to apply custom curves and adjust the parameters of the images. Within the boundaries that Graeme described in my quote of him above, and his posts on this thread, I see my workflow with RED One to most closely approximate that of my DSLR workflow, at the acquisition stage and in the processing of the RAW files before editing - keeping in mind the obvious differences in using motion cameras as opposed to still cameras.

RED One is a convergence camera system, using S35mm and S16 cine lenses, 35mm still lenses, B4 2/3” lenses, RAW and RGB, and thus can be accessorized and lensed for a wide variety of cine-style and EFP style production genres. Beyond it’s utility, I think the cool thing about RED One is that it brings together all the “tribes” of the motion media community - and in the process, the input, techniques, and technology of cinematographers, videographers, and still photographers will help further the boundaries of professional image making.

Media convergence is upon us...


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Good to have you here on RED User Dave – your insight is welcome and valuable to this think tank of a community.

 

[TimothyD]

Media convergence is upon us...

That is a truly liberating thing Gibby, and I welcome it.

You were right on with everything you said about my camera and workflow.

I think for starters considering my limited budget, I'll be going with screw on filters. And while there will be occasions where I probably could benefit from a clip-on mattebox, I will give using screw on filters a shot first.

He’ll probably be using the exposure tools that RED has developed for the RED One camera: an interactive histogram and a waveform monitor that are viewable on the EVF or LCD, either full view, or in scaled down version in the periphery of the frame.

It sounds as if the histogram and waveform monitor are going to be extremely helpful no matter what the situation. I'm guessing that between shooting RAW, using the zebra, histogram and waveform monitor it should be possible to first be in the ballpark, and then tweak appropriately in post.

I had read in a thread mentioning the supergrip, that by setting button presets on it, you will be able to adjust gain on each channel to avoid clipping. Do you think this will be something that is necessary for the average shooter, like myself? I can imagine it being a useful tool, but do you think being able to control them on the run will be necessary?

I suppose I should mention that the content and nature of what I shoot is essentially a documentary style. There are situations that require something more akin to ENG style at times, but more often I have time to plan and prepare a bit. I never use lights of any kind, except when shooting interviews, in which case I usually use a Lowell LC-55 soft box. I will maybe splash some light on the background, and occasionally use a backlight. So as you can imagine, I never shoot anything that requires intense tweaking to try to capture a particular look. The only thing I ever shoot that needs to have a cinematic quality are campus scenics. When shooting scenics I always have the opportunity to plan and experiment, and choose the days I shoot them based on a combination of weather and the number of students on campus. (shots of campus with no students = bad scenics I work for Public Relations, so we want nice looking footage of students enjoying the campus.


I shoot almost entirely indoors during the winter months (Michigan) and primarily outdoors during the summer, aside from interviews (which also can often be outdoors when it is nice out).


Once again Gibby I want to thank you for taking the time to share your knowledge. You would make a great video/film professor

Tim

 

[TimothyD]

Also Gibby, your discussion of the similarity of Red and DSLR's made me realize that I should borrow one of the cameras from our in-house photographer and do some experimenting with RAW.

I myself, being just out of grad school have never had the money to buy a digital body to replace my old Nikon, yet...

I imagine some experimenting could really help me prepare to transition to the Red. Sadly, I won't be ordering my Red until July 1st, which means I will have a LOOOONG wait before it finally arrives, sometime next year from what I've read. (Red Team: I think you might want to think about building a few dozen factories considering the demand you are going to see for this camera

 

[Steve Gibby]

As always, glad to help Timothy....

In answer to your question about the SuperGrip, If you're using a 12 volt auxiliary powered B4 2/3" HD lens with RED One you'll have zoom power to the rocker switch on your lens. The SuperGrip sounds real interesting - I've also been checking it out. The posts about the SuperGrip by Stuart English that tweaked my interest are these:

"We brought a couple of non-operational prototypes of the SuperGrip to NAB to get some feedback on functionality and price points.

Pricing and delivery dates for SuperGrip and RED MOTOR will be announced later.

The buttons on the SuperGrip act as extensions to the camera control surfaces, i.e the buttons can be programmed to do whatever you want them to do - White Balance, Clip Replay etc etc The force sensitive key can be attached to a number of devices - motors, audio levels, shutter speeds - whatever is most appropriate to your application.

Stuart English
4/27/07
RED User
http://www.reduser.net/forum/showthread.php?p=35700&posted=1#post35700


That same comment about these buttons being extensions of the camera control surface can also be applied to the RED EVF viewfinder keys and potentiometer BTW...

Stuart (same thread)"


If we can interactively control the functions he mentions from the SuperGrip that's very cool. I will buy a SuperGrip, no doubt.

Definitely...get a DSLR and learn the RAW workflow. It will help you with your approach to RED One.

As for being a professor, I've taught and mentored many "students" in on-the-job training during my career. I've also taught workshops at film festivals. I enjoy it! I love college. I have a bachelors degree and a total of six years of college completed, all of which overlapped my working career in motion media. Learning is a never-ending process in as tech-intensive an industry as ours. I get up each morning fully expecting to learn a ton of new things about creating images...and I usually do. We never arrive at a destination in this industry...we only pass stations along the way. I wouldn't have it any other way...

 

[Ralph Oshiro]

I suspect that with these wider-latitude digital cameras, the noise issues from rating it at 5500K versus 3200K are not significant enough to warrant color-correction filters. And the trouble is that while it would be easy to use something like an 85 filter outdoors if it would help noise problems, I think the "native" balance of these sensors (where they are happiest) is closer to daylight than tungsten, and it's really not practical to use blue filters indoors when shooting in tungsten balance due to the high filter factor of blue and the low light levels employed by tungsten.

People forget just how far in the red spectrum tungsten lamps are -- even tungsten-balance color negative has to design a fast and therefore grainy blue layer just to compensate.

Yeah. My DSR450 is very pretty, but I'm starting to notice that it seems to white balance shockingly differently than, say, the BVW400s/600s I shoot with at work. Check this out: I'm currently shooting a personal short film with my DSR450. It's a night interior that's strongly backlit with a Joker400 HMI. Even though I'm on my daylight preset, the DSR450 photographs the Joker's output as slightly "blue." (I've used this exact same Joker at work with a BVW400 on its 5600K preset, and it photographs perfectly white.) I also have daylight flourescent desk lamps ("Ott" lights) as practicals sitting on a desk in the scene. They balance very "white" on the daylight DSR450 preset. Then, I fill the actress from a standard, 2-foot, 2-bank KinoFlo, lamped at 3200K. The Kino (which usually photographs a bit weird on video anyway) balances just fine--in other words, the 3200K-lamped Kino photographs "white" on the same 5600K DSR450 preset, with only the slightest "hint" of "warm." I've never seen a video camera, with this combination of sources, render the color that way. Weird. But it looked great, and was exactly what I wanted. (I would post a frame, but that violates a contest rule.)