DSC's TechTip
for June 2008 comes from

George Walkley

The Topic:

"Matching the Sony EX-1 with more costly Broadcast Cameras"

"Matching the Sony EX-1 with more costly Broadcast Camera's"

We have been creating custom profiles recently for our customers who have purchased XDCAM, HDCAM, and Sony’s new PMW-EX1 and other cameras.  We need to match them all for particular clients for particular shooting environments.   It is absolutely necessary when creating profiles to have the correct aides to guide you and to have the end user with you (important) so that he/she is comfortable with the final look you create.
 
All of the menus are just numbers that you adjust for the response you want.  Unless you have a calibrated monitor, calibrated chart that is correctly lit and so forth, you can tweak all you want and not come up with the result you would like.  As a tech I understand this, but rather than confirming that factory specs are giving a correct response, I dive into having fun creating picture profiles or scene profiles with the customer, while keeping away from undesirable responses. 
 
One thing that is a must with HD is avoiding washed out high-lights that get blown out as soon as the scene is saturated with light.  All the cameras listed above plus some others really need some help as they come out of the box.  DSC Labs’ charts help with developing chroma profiles, black stretch adjustments, flare adjustments, etc, with confidence.  Because the EX1 is loaded with things to tweak, including an individual color with phase and saturation ability, the ChromaDuMonde chart really helps me confirm that I’m getting the result I want without getting unsatisfactory results in other areas of the setup.
 
I have gotten tons of compliments from our clients that shoot major outdoor and other types of projects with a variety of cameras on the same shoot.  The cameras will all have the same profile characteristics - PMW-EX1, PDW-355’s, and HDW-730’s for example.  What’s amazing is the Sony EX1 and just how great it looks, especially for the money.  I’m not trying to sell an EX1 but I have to admit the blacks look awesome, the chroma is fabulous and the grey scale is superb.
 
These new cameras allow you to tweak your ‘---‘ off, but you need a guide to do it properly!  A good chart is a must.

DSC's TechTip
for April 2008 comes from

David Blackham

The Topic:

"Continuous Light Sources"

"Continuous Light Sources"

There is a growing trend to use fluorescent, LED and discharge light sources for film and video production.  This is good news for the environment as these light sources use less power than conventional studio lights.  As the power consumption is less, so less heat is generated on set.   Environmental issues should not be ignored when considering technical and creative requirements for production - being environmentally responsible has practical benefits too!

One of the problems faced by these light sources is the lack of continuous spectrum activity, exemplified in fluorescents, LED and other discharge fixtures. It is impossible to add light that was not present in the first place but spikes can be removed with suitable gels (e.g. minus green for green spikes). Often, light sources originally designed for film and television are used with video – this is common on productions with lower budgets, and may be why there are so many brands of CFL bulbs.  If selected with care, many of the quality bulbs have a high CRI and are useful sources of light. Video and digital cameras have a greater tolerance to low CRI light sources and they can be easily balanced during image capture, but only when a neutral DSC test pattern is as a reference.  CRI figures are not a guarantee that the source has a continuous spectrum, but can be helpful when selecting potential light sources.  Much of this information can be found on the internet.

When using new fluorescent tubes from any manufacturer, a common practice is to burn the tube in for at least 24 hours before use.  This allows the tube to stabilize and become consistent in its output.  Try and use light sources with a high CRI and suitable CCT when budgets allow. Occasionally, light sources that deviate from 3200k or 5600k are welcome on set, so long as the quality of light from the source remains constant in terms of CCT and spectrum. A meter is not always necessary to determine colour temperature as many Digital cameras have onboard indicators.

A guide to monitoring continuous spectrums of light is easy with DSC Laboratories test patterns. The front lit ChromaDuMonde 28R is a necessity to identify light sources that may not have a continuous spectrum. If the camera is calibrated with a continuous source (such as tungsten lamp) then a similar colour temperature fluorescent source can be compared on a vectorscope display. This may not be standard practice, but this technique is useful as it requires basic tools found on common sets.  Monitor calibration is of equal importance - especially when shooting on location.  I use a Spyder 3 monitor calibration device made by Datacolor. Location viewing environments may not be the perfect calibration spot, but the device is simple and, when paired with a DSC Pattern, easy to use when trying to achieve perfectly neutral imagery.

DSC's TechTip
for March 2008 comes from

D. Gregor Hagy

The Topic:

"Red One and CMOS Static"

Learn more about Gregor here

"Red One and CMOS Static"

Every time you change a lens on a digital camera such as the Red One, be sure to check the sensor for dust. The single CMOS sensor has a static charge that attracts dust (just like DSLRs). Use a loop to magnify the sensor before blowing gently with a blower bulb or compressed air.  If blowing won't remove the dust, then use a brush designed to clean DSLR sensors, but use it with great care. 

When dust is left on the sensor it appears as a soft grey blob in the image. This is not always visible on small displays and might not be noticed unless you see your work on a large display or projector.

DSC's TechTip
for September 2007 comes from

Greg Foad

The Topic:

"Are Six Colors Enough?"

Learn more about Greg here

"Are Six Colors Enough?"

Believe it or not, the camera that shot this 28 color ChromaDuMonde was accurately aligned to a six color CamAlign chart (note - the six primary colors are still in their boxes).  With the advanced handles on many HD cameras, matrix alignment can be misleading.  

The testing lab at DSC reminded me of a crash test dummy plant.  Various test charts and wacky designs lay everywhere - some had been yellowed from radiation exposure, others bent in testing shipping packaging, and others were just designs that never made it past the testing stage.  I was there to help DSC capture image scenes onto a WFM7100 USB buffer for an application note they were writing for Tektronix.  We used my Sony F900 to test color reproduction using different test patterns.

What we came across was quite astounding.  We first used a standard CamAlign six color pattern with crossed grayscales.  With only six colors to work with, the multi matrix controls on the F900 allowed me to put each color in its box very quickly - camera alignment took no more than 10 minutes… or so we thought.  The green and cyan dots seemed to have an oblong shape, so I was skeptical that we had aligned them correctly.  Sure enough after putting up a 28 color ChromaDuMonde, we saw the vastly misshapen hexagon.  One goal of camera alignment is to adjust its taking characteristics to accurately reproduce the widest possible range of colors – not so in the first image.  Clearly, we would be better off using one of the factory presets then using this skewed matrix.

While both user and multi matrix settings appear in the paint menu of the camera, they have very different functions.  The user matrix was originally intended to help warm or cool an image, depending on the shot.  The algorithms behind this circuitry grab clusters of colors and pull them fore and aft, i.e. R-B, B-Y, etc.  The multi matrix controls uniquely allow selective color enhancement and hue adjustments up to 20 degrees.  These controls are powerful, as they only select one color independent of any intermediaries.  So, the correct alignment sequence is to adjust the user matrix first, and then use the multi matrix controls for fine tuning.

So, this tech tip begs the question – are six colors enough?

DSC's TechTip
for June 2007 comes from

Bruce Alan Greene

Originally appearing on the CML site it is reprinted with kind permission from Bruce and the CML

The Topic:

"Varicam Detail"

Learn more about Bruce here

"Varicam Detail"

On my last major Varicam project I conducted a film out test and included a variety of detail settings in the test.  After viewing the film print on the big screen I selected a level of detail that I believed added enough "punch" to the image without any noticeable detail artifacts visible in the print. In the test I was surprised by how much added detail the film print would tolerate, though to be fair, I've developed a subtle eye for "Sharpening" through years of Photoshop work.

For the Varicam, I decided that "Master Detail" could be set as high as "0" before I didn't like the look. To be on the safe side, I shot with master detail set to minus 2. At the factory defaults for all the detail parameters on the Varicam, master detail = -7 is the same as "detail off". Master detail set to "0" is a significant amount of detail on the Varicam.  For the most part I ended up happy with my detail setting until...I had a shot of a woman against a bright blue sky. On my 17in LCD monitor, I could just start to see an outline where the woman met the sky. I then dialed down my setting a couple notches. 

My advice for anyone brave enough to turn on the detail is to view your test image and test charts on a large LCD monitor that has a true pixel to pixel representation of the image. I think if one judges by CRT then one is apt to add too much.  Also, it is very important to use a waveform monitor when adjusting the detail. You will see changes in the detail settings on the waveform that you will miss by looking only at a monitor. 

I hope this is of some help to those interested in this discussion.

Bruce Alan Greene
Los Angeles

DSC's TechTip
for April 2007 comes from our

User Database Reports

This is a compilation of similar ideas from a number of different users.

The Topic:

"Noise, Green, Cyan, and Saturation"

"Noise, Green, Cyan, and Saturation"
 

When data acquisition for scientific applications is the main purpose of image capture, precise camera setup is of even greater importance.  For that reason, we are used to hearing very specific guidelines from clients that the norm does not always follow – for instance, some of our clients capture only in a progressive field mode, as testing has shown interlaced to be less reliable (an arguable, but tested opinion!).  Another pertinent example includes lining up a DSC Labs ChromaDuMonde with 80% Green and Cyan saturation, as opposed to lining them up directly in their vectorscope boxes.  Some clients align the phase of the green and cyan chips to be in plane with their appropriate vector boxes; however when boosting the saturation values, they do not max that setting out on the camera just to get the greens and cyan's square within their boxes.  As many cameras come from the factory with greatly warmed G’s and Cy’s, clients have found themselves maxing out our saturation values in order to get the colors deadset in their boxes and this can create a fair amount of noise in the darker areas of the image - this will vary from camera to camera.  Operating with a buffer is a good engineering tip. 

One client recently described the process as follows - 'For simplicity's sake, let’s use a Varicam to quantify this process.  Take a DSC Labs ChromaDuMonde 28 color pattern, and using the Color Matrix and Color Correction settings, align Y, R, Mg and B up, whilst aiming the G and Cy chips at their targets.  Then, we increase the saturation of these chips within the color corrector until we are at about 20% of where they should be.  As the Y, R, Mg and B chips are already near their boxes, setting these colors is relatively easy.  The G and Cy chips however, are much farther from their targets, and therefore require a significant boost in gain, even though we do all of our set ups with a zero gain setting. When all of the colors are lined up, the end result is a bit noisy, as if we were lining up with an increase in gain.  The same increase in dynamic range as used in the ‘gain’ setting must be applied to the saturation settings within the camera’s color correction controls.  This process may be considered subjective, and we are not preaching it as gospel, however it produces a satisfactory colorspace with a limited amount of noise, which works perfectly for us.'

DSC's TechTip
for February 2007 is from

David Mullen, ASC

Originally appearing on the CML site it is reprinted with kind permission from David and the CML

The subject

"Tips on HD"

Learn more about David here

DSC's TechTip
for December 2006 is from

Art Adams

Originally appearing on the CML site it is reprinted with kind permission from Art and the CML

The subject

"Green Screen Technique"

Learn more about Art at http://www.artadams.net/

DSC's TechTip
for June 2006 is from

Robert Goodman

Emmy-nominated director and  the author of the "Goodman's Guide" series of field guides for SD and HD cameras

The subject

"Creating a Look"

Learn more about Robert here

"Creating a Look"

Creating special looks for any camera starts with a baseline. I establish that baseline using a ChromaDuMonde chart.  Once you set the camera up to what is essentially normalized technical accurate reproduction, you can begin to deviate from that norm.

Manufacturers generally set up the camera at the factory to reproduce pleasing skin tones by altering the color gamut of the camera. This is no different than Eastman Kodak color balancing Kodachrome so it reproduced bluer skies and reds more brilliantly than were often present in the actual scene.  Fujichrome made greens look more lush and skin tones creamier than reality.  And you can do the same with most of today's digital cameras.

Under DAYLIGHT BALANCED lighting, shoot a ChromaDuMonde chart and use the camera's controls to reproduce it on a Vectorscope so all the main targets are in their boxes.  You'll need to increase the gain to approximately 1.875 instead of the CAL (calibrated) setting because of saturation.  Make sure you have a evaluation grade monitor preferably a CRT or one of the carefully calibrated LCD monitors, which are costly though less costly than the evaluation grade HD CRTs.

With the proper tools, you can begin to create your own looks.  Want a warmer, more pleasing look than the "technically accurate" look you just created?  Adjust the camera's controls to skew the color reproduction of the blues and cyans towards the reds and yellows.  Want a cooler look? Skew the color reproduction of magentas, reds, and yellows towards blue and cyan.  It will take a lot of trial and error to get what you want.

Pay careful attention to the impact of changes on the intermediate colors.  Try to keep the spacing between intermediate colors on the vectorscope uniform.  Remember that when you skew the color reproduction, you are eliminating colors so don't go too far overboard if you want to reproduce a nearly full color gamut.

Have fun and let yourself go overboard.  In making adjustments you'll discover the limits of the camera and perhaps a stunning look.  Every shot doesn't need to reproduce color accurately.  A cinematographer's job is to depict emotional truths.   Accuracy is for scientists.

A few final words: Style is over-emphasized; if the audience is watching what the cinematographer is doing they aren't involved in the story.  Subtle color changes resonate and alter the mood of audiences in ways that heavily filtered images never can.

Robert Goodman has conducted workshops on digital production and post for AIVF, Guild of Professional Photographers, IFP, ITVA, SMPTE, Sony Corporation, Women in Film, and at film festivals in Atlanta, Austin, Los Angeles, Minneapolis, New York, Philadelphia, Portland, San Diego, and San Francisco.

DSC's first Tech Tip of 2007 came from:
Dave Blackham -
 Head of Operations - Grenada Bristol, UK.

The subject - Motion Artifacts

When shooting progressive material on an HD camera, do your best to keep camera moves (i.e. pans, tilts, tracks etc) at an optimum speed* to suit the capture frame rate so as to avoid motion artifacts.    Motion artifacts appear perceptibly worse the sharper the image and the increased depth of field that HD cameras can offer is not always helpful when it comes to avoiding this issue.

Using preferred camera move speeds may not always be possible depending on the action. However, using a suitable adjustment of shutter angle and proper use of iris and NDs to reduce depth of field, thus keeping  the object of interest in focus and the background out of focus, is one technique which may help reduce unwanted artifacts. Adjusting the frame rate on a Varicam to suit a desired pan speed can also help work around motion artifact issues.

*The American Cinematographer's Handbook, amongst others, lists useful camera frame rate/pan speed data.

DSC's December "TechTip" was from:

Reid Robertson - Digital Camcorder Specialist with Panasonic Canada.

Reid's Subject - Back Focus:

Always remember when performing a "flange-back" adjustment (as Back Focus is sometimes called) the Iris should be FULLY OPEN. When the Iris is wide open, the depth of field is minimized, giving you the optimum focus point during your adjustment.

When there is too much light, use the ND filters in the filter wheel to cut it down to a useable level. If there are no ND filters available, use the "Poor Man's ND": higher Shutter speeds (this trick comes from the CCTV world). I cheat and also use the Viewfinder Peaking set to maximum, to find the best focus during the adjustment.
Rebuttals on Back Focus:
Just received your tech tips #9. With all respect, the suggestion to use max vf peaking, is suspect, in the same sense that doing a back focus at f/16 would be wrong. The idea is to make it more difficult, and more critical, than less so. My recommendation is always minimum (or just the least bit) of viewfinder peaking. - A. L. New York
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Hello DSC, a comment from someone who used to work for a HD colour viewfinder manufacturer - on Sony 730/750/900 we used to find that setting the VF peaking at about +70 (It goes from -99 to +99, with 0 being the default) gives a much better image on which to judge focus. Note, setting this peaking does NOT affect the image recorded to tape, it purely lifts the transitional edges slightly in the VF so that they "Snap In" at the point of critical focus. - RB London UK
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I guess by "difficult" the commenter means "difficult to be satisfied with what you see" rather than "difficult to obtain the desired result"?

Let us define "difficult" in the most common connotation of "difficult to do." Then, less sensitive = MORE difficult to see and do. More difficult = LESS sensitive! You want it more sensitive, yes! But less difficult to see the right adjustment. That's why you don't use f/16, which makes it LESS sensitive and MORE difficult. Max peaking, on the other hand, lets you see a slight decrease in sharpness as you move away from the optimum point. MORE sensitive and LESS difficult. - WB Illinois
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Here's the correct way to do it, real easy.
Open up the iris completely, and get your camera to deal with the light. Use any means available such as shutter and filter wheel to get the camera to deal with the lens wide open. Next zoom in completely and focus on your subject. Then zoom out completely and adjust back focus. Repeat a couple of times since these adjustments interact slightly.
This is the best way to do it, because this provides you with an individual back focus setting for your specific shot. Not a problem normally except if you have a really good lens coupled with a very good camera. Normally, you should just do this for a shot at infinity, and leave the lens set up this way for the next person using it.
Viewfinder peaking helps find the "sweet spot", always maximize it if you need to. Main problem with Back Focus is that people don't get that the Iris has to be WIDE open doing this.
Reason is simple. Before lenses we had pinhole cameras. They were really cool. A box with a pinhole in it and a piece of film on the other side. No problem with any focusing of the lens whatsoever, and always a great shot. Might take half an hour to get a good shot without anyone moving their face. Probably why old photos show grumpy looking people. - JK CA
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As far as I can tell, the cameramen I work with, who've also been doing this for 25+ years, do just the opposite of what this fellow above suggests.

They crank the living daylights out of their viewfinder peaking. Their objective is to make the image jump off the eyepiece and into their eyeballs when they've hit critical focus.

I do the same thing when I'm adjusting back focus, or doing other focus critical alignments.
LC - NY
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Setting VF peaking to max for back focus alignment, was also very suspect to me. Depending on the condition of VF and camera, it's someVerdanaecessary to use a certain amount of peaking in order to get the best result, but only in the very wide position of the zoom.
That's how I do it sometimes, but as soon I zoom to the tele position, to adjust the focus, I turn down the peaking. That's more work to do (especially when repeating the procedure many times...), but it pays.
I think, the max VF peaking might only be suitable for an "emergency setting" in the field, when no Siemens star is available and whatever is in front of the lens has to work as a test chart. Best regards from Switzerland - MR
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Gee, if we are going to turn the viewfinder peaking down, I guess we should go back inside the camera and turn off the enhancement contours like my engineer friends did back in the Norelco PC-70 days! That would help even more to make it nearly impossible to get meaningful results under field conditions.

Viewfinder peaking is on a display, therefore it enhances what you CAN see. If you would look at a waveform monitor you would see the same thing that peaking shows on the viewfinder - a very stark "snap" in and out of focus. Peaking (and the waveform monitor) is also helpful in cases where you are too far from the chart and it is too hard to see detail at the wide angle setting. How far should we be from that chart, anyhow? And repeat the process at least twice. DG Iowa