HOW TO GET THE MOST OUT OF YOUR FILM FOR HD TRANSFER
This is guide is intended for students, independent filmmakers, or anyone making their first foray into shooting 16mm or Super 16 film for HD transfer. In no way is this guide intended as a replacement for on-hands training and instruction provided by film schools, professionals, or critical first-hand experience in 16mm film production. Our recommendations are based on our observations of common problems and issues that we have noticed in transferring 16mm or Super 16 film to HD and how we feel filmmakers can get the most out of their HD transfers.
Many issues such as excessive film grain are consequences of choices that are made before we even receive the film to process, thus making it harder and more expensive to correct for them in the transfer stage. We strongly urge communicating and coordinating with labs and transfer facilities in the planning stages of your production as a general rule which will hopefully improve the quality of your transfers and the overall finished product.
Your success is our success.
DO I REALLY NEED AN HD TRANSFER?
This is the first question all filmmakers should ask themselves before committing themselves to getting HD video dailies. Transferring your film in HD is a much larger financial investment than SD (standard definition) transfers and can bring up a number of critical technical issues inherent in HD post-production, the most obvious of which are larger file sizes and the need for faster sustained transfer rates for your hardware to handle.
This guide will try to highlight some of common issues that you may not have realized in the pre-production phase. Not every issue is covered in this guide as the world of HD can be incredibly complex and is constantly evolving as we write this. We’re not trying to discourage or scare anyone away from shooting 16mm film for an HD transfer but you need to be clear on why exactly it is worth the extra costs and sometimes the extra hassle.
Some students seem to operate under the assumption that they “need” to have an HD transfer or that it will “improve” their film in and by itself. The world of HD actually increases the scrutiny of your image and decreases your margin for error. When done well, the results are extremely rewarding but it certainly shouldn’t be seen as automatically making it easier for your DP or production crew.
SOME HISTORY ON S-16 AND ITS ROLE IN INDIE AND HOLLYWOOD PRODUCTION
Eastman Kodak developed 16mm film in 1923 as a more accessible amateur format to the professional 35mm format. Since 35mm film was shot on highly flammable nitrocellulose film stock, 16mm was chosen as a gauge so that people couldn’t easily slit a 35mm film and get two 16mm strips. Acetate, or safety film as it’s also known, was manufactured specifically for 16mm.
More professional use of 16mm began a decade later in the educational film market, which required area for an optical soundtrack, and thus, the removal of perforations on one side of the film. Popularity of 16mm grew due to it being cheaper and more portable than 35mm film equipment and it seemed especially suited for television production which had smaller budgets and, ultimately, a smaller screen for public display. In light of the cost savings, the image quality didn’t really suffer.
Televisions, however, evolved over the years becoming bigger and better. As a result of this and more professional competition with 35mm, S-16 was developed to take advantage of the extra area of single-perf 16mm film and get a 25% bigger image. The loss of the area previously reserved for an optical soundtrack, however, meant that S-16 filmmakers had to either finish on video or optically blow-up their S-16 negative to 35mm, where a soundtrack could be added. Since television production doesn’t need to finish on film, many nationally-broadcasted television series shot on S-16 just to transfer to video.
With the increasing popularity of HD televisions however, those days are now fading as many television programs are switching to HD video or 3-perf 35mm film. High definition and big flat screen televisions have opened up a new scrutiny of how things look when the video resolution is twice what it was and the viewing monitor is in many cases much larger. Film grain and defects that used to not show up, now do.
Anyone who has ever shot super 8mm negative and 16mm negative and gotten a standard def video transfer of both has seen that the super 8 looks a bit grainier and less sharp than the 16mm. For Super 8, the telecine is blowing up a frame that is smaller than your pinkie fingernail to a much larger size for viewing. The same holds true in the size difference between 16mm and 35mm and how the two formats compare in the world of HD.
WHAT IS ULTRA-16 AND DO YOU TRANSFER IT?
The standard frame for HD is 16:9 or 1.78:1. An unmasked S-16 frame is 1.66:1 which will require an additional matte to be applied (and minor loss of image) to achieve 16:9. Ultra-16 is a format that uses 16mm film to natively achieve a 16:9 ratio by limiting the vertical image area to being strictly between the perforations while expanding the horizontal image over into the area beyond the start of the perforations. This was designed as a possible 16mm answer to the increasing demands of HD transfers and distribution.
Currently, Colorlab can ONLY PROCESS Ultra-16 as we do not have transfer gates designed to capture the extra horizontal image beyond the perforations on the drive-side of the film.
HOW TO GET THE MOST OUT OF YOUR FILM FOR HD TRANSFERS
Choosing Film Stocks
Most of our clients do not have a budget that will allow for shooting in 35mm, so you must be smart about how to proceed in regular 16 or super 16mm. The first step is choosing film stocks, determining in which situations they will be used, and how to optimize their potential through lighting and exposure.
Kodak has been pro-active since the turn of the century in updating their negative stocks for the arrival of high definition. With the exception of 7229, their stocks offer tighter grain structure than their older lines of negatives. In the case of B&W, there is no new and improved negative, but a tighter grain structure can be achieved by shooting B&W reversal film and cross-processing it, which turns the image into a negative. With the color stocks, the slower the film speed, the tighter the grain structure.
Many students use 7219 exclusively as it is the fastest of films and can cover everything from low-light night street scenes to broad daylight, and, if exposed properly, it can work. However, it is not a substitute for no light. Many times we have seen exterior night scenes where large sections are nothing but black unless the camera passes a lit store front or lingers beneath a streetlight. The grain structure is not very tight and the difference shows up immediately in an HD telecine. Therefore, Colorlab does not recommend using 500 EI stocks for eventual HD transfer. You will get better results with a slightly slower speed stock and a little more lighting.
At the other end of exposure issues, using 7219 in broad daylight will not look nearly as good as using 7201 properly exposed. This slower stock, when given the extra light it needs, rewards the filmmaker with vivid colors and crisp contrast. But the caveat is that 7201, rated 50 EI daylight, requires a lot of light. A cloudy day will desaturate the colors. Late day shadows, even while the sunlit parts remain vibrant, will precipitously diminish shadow detail. Losing your light at twilight will render this stock flat and dull, no matter how wide open the camera’s iris is. When shooting outside, it is a good idea to have two different stocks with you so that if you were hoping to shoot 7201 or 7205 but it is overcast, you can go to 7212 or 7217, which are medium speed films, as a backup.
Most importantly, use brand new film stock! Many are tempted to buy short ends or use rolls previously purchased and kept in the fridge. Maybe it will work out but maybe it won’t. Film has a shelf life of about 6 months and over time it begins to attain something known as age fog which highlights the grain in the film to the point where it is noticeably visible. It also makes your properly exposed film seem underexposed, hence the ‘fog’ reference.
There are many ways to save money on your budget, but raw stock is NOT the place to do it. It is the most important part of your finished product – the look of your film. If you insist on using older films, however, you can have them clip tested at the lab to check for age fog. Depending on the number of rolls, we will usually perform clip tests for free.
Your film stock is also vulnerable to other factors such as heat and x-rays so please process your film as soon as possible, don’t leave your film in a hot car or other uncontrolled environment, and be careful when shipping your film. FedEx and UPS do not use x-rays but if you travel internationally, you may encounter them.
If using 7219 or 7229 (both 500 EI) beware of ‘hot spot lighting’ where a source of lighting is too close to the actors at the side or pooled in one spot of the composition where you don’t necessarily want the viewer’s eye to go. It may also occur if you bounce light off the ceiling while part of the ceiling is in your shot. This will cause the part of the image that has too much light to bloom, which will wipe out detail and look unnatural. Faster films respond better to flatter or more diffuse lighting situations. Slower films work better with a lighting scheme designed to increase contrast.
7229 is a film that is sort of grainy, apparently at the request of filmmakers that wanted more grain in their film. They may be shooting the 35mm version, however, which is more forgiving. It is a film stock in a pastel pallet. If you are seeking a desaturated look without the grain, try shooting 7219 and ask the colorist to roll the color back a bit. Or better yet, reduce the chrominance in post-production, preserving your color and leaving your options open if you end up not liking the desaturated look.
Picking the right stock is important but it won’t help you if it isn’t exposed properly. Many students tell us their professor suggested overexposing the film by one stop to increase contrast. In theory, there is some sense to this if you consider that underexposure robs film of contrast. However, this is more of a trick than a sound practice and we do not recommend it for 16mm in high definition. The more you overexpose film, the less natural and more muddied colors become and the image becomes grainier. And if you accidentally overexpose by more than a stop or two, the degradation of the image is compounded. Conversely, underexposure saps the colors, lessens the contrast, and turns what should be blacks into milky grays. Grain and noise will also increase as we will have to stretch the contrast to make it look normal. The more severe the issue is, the less flattering the results.
Contrast is best achieved through lighting with a thoughtful lighting set-up creating lit and unlit portions of your composition. If you’re outdoors, try to use the slower films at the right exposure on a sunny day. Lighting, in concert with correct exposure, is where contrast comes from. It will require some additional planning in pre-production and possibly some higher costs and time during production, but details and discipline is what good filmmaking is all about.
In the absence of incorporating contrast in your film through lighting, shoot the exposure close to dead-on and ask the colorist to try and add a bit of contrast by crushing the blacks a bit while lifting the whites. Just keep in mind there is only so much that we can pull out of a flat lighting setup.
Highly Stylized Looks
Many students like to create highly stylized looks such as hi-contrast film noir, bleach bypass, cross-processed color reversal, etc. Such looks require a lot of planning, preparation, and skill to pull off and a lot of color correction in post as well. As such, we recommend at a minimum a Bestlight transfer if not a Fully Corrected Scene-by-Scene transfer for these types of shooting styles. Many of these looks require extensive color correction during the transfer and even after the transfer to fine-tune color and contrast. You may still ask for a Onelight transfer, but please note that you will likely need to apply a lot of correction on a scene-by-scene, if not shot-by-shot, basis. The Onelight transfer we would give you would be “flat” so to speak with minimal clipping on the highlights and the shadows to give you maximum leverage to continue color correction in post.
Please also describe to us in detail how you want your film to look. If you want grain, let us know because we usually run a powerful DVNR 2K Grain and Noise Reducer on all HD transfers, which may remove the grain you want and give you a more processed, less organic look. If you shot under mixed lighting such as tungsten and fluorescents, please let us know which light source to correct for (or at least how you want the skin tones to look). Perhaps you want the sickly green hue that fluorescents can cast or maybe you don’t. Don’t assume we know. If you want to retain odd colors that film captures from various lighting sources, please let us know. Our default is to make the skin tones look natural. but trying to find “natural” between mixed lighting sources can be difficult. Sometimes it looks more natural to shoot under a single light source such as fluorescents without any additional tungsten lighting and then correct for the fluorescents’ green hue during the transfer.
We also strongly recommend first testing your look with a 100’ roll to make sure that what you shoot ends up how you envisioned it. Perhaps you previously obtained a look you liked in standard definition transfers by underexposing the film or by flashing the film before processing which may cause more grain to be picked up in a high definition transfer. Despite your level of experience, even professional DP’s in Hollywood will meticulously test various film stocks and looks before production to verify that their transfers and final products end up on screen as they envisioned them. Please don’t rely on what others tell you will look good on screen; test it and see it for yourself!
If your project is going to be more than a few thousand feet of negative, you are embarking on a fairly ambitious production with a sizable financial investment. It would then be wise to conduct a camera test to verify that the lighting and exposure decisions you plan to make will produce the results you are looking for. This includes the exposure needs and looks of certain film stocks in particular and, most importantly, the working condition of your camera. Film school and rental cameras are prone to being overused and under-maintained. Previous users might not report problems with the camera and technicians who take care of the cameras might have overlooked a potential flaw.
We have seen numerous large productions that would have benefited immensely from a simple test prior to production. A
100 foot roll of film and a one light video transfer could be your insurance against a catastrophe. Remember, a scratch or hair on your negative will look that much more crisp and defined in high definition.
The single most devastating camera problem we encounter is a back focus alignment issue with zoom lenses. If it is out of alignment, this means your focus won’t hold when you zoom in or out. Be sure to test for this by starting a shot with a tight close-up and continue to roll while zooming out.
Although some people think of HD as being a sharper image, focus issues will NOT be solved by an HD transfer. It will actually make focus issues even more prevalent since HD brings a higher level of scrutiny and a lower margin of error. If you think you have issues with your focus, you really should consider SD video instead of HD.
Another common camera problem is a registration problem which is usually associated with the pressure plate inside the camera’s gate. It can have a minor effect on your film, being almost unnoticeable unless light sources such as a candle or a light bulb or a street lamp within the composition appear to bleed light downwards and upwards. A more pronounced registration problem could cause your image to bounce up and down. In its worst manifestation there can be a total loss of stable image, known as a ‘lost loop’, resulting not necessarily in a pressure plate issue, but from an improper-sized loop feeding from the magazine into the camera’s gate. In short, the bigger the screen the image is displayed on, the more noticeable movement can be.
The best way to test for registration is to shoot two passes over the same piece of film in a locked down shot of a lined grid. This allows the reference to be between one exposure and the next, not the image and the film. Once the first pass is completed, turn the grid on its axis by rotating it by a few degrees and offset diagonally less than the width of the lines. In viewing the test, any movement up and down between the two vertical lines indicates a horizontal registration problem. Motion between the two horizontal lines points to vertical registration problems. It is important to have the camera and chart well supported and stabilized during the execution of this test.
It is important to start with the film being exposed properly according to the film’s rating and a light meter. You want to begin with the correct exposure because you should order a strict one-light video transfer from the lab so you can see the changes in the film once you start changing the exposures. The best set up is to have a color chart and a gray scale in a medium or semi-wide shot with a human being present. They will be in your film, so you might as well see how they look in your test under the lights. It is also a good idea to have a slate to record the number of half-stops you are going over or under as a reference. None of the shots need to be longer than five seconds. If starting from normal to overexposure, go the full distance of stops, then return to normal and proceed toward underexposing. You should also take notes of the sequence of exposures, as some of the extremes of exposure will make your slate unreadable.
If you are testing for different set-ups such as indoors and outdoors, or different lighting scenarios, order a video best light with instructions to correct at each new set-up. If testing with gels, it is imperative that you start with no gels on your lights, so the colorist can set up the color and gray scale in neutral lighting. Colorists might render your colorfully gelled scene to look normal if you shoot the reference charts with the gels on your lights. Once you begin production, it is very important to get in the good habit of shooting your color and gray scales at the beginning of each set up, as we do not go fast forwarding in search of your charts even if told where they can be found. If shooting a framing chart, make sure that it gets filmed at the head of the first camera roll.
During production, always shoot the charts with all the lights on you will be using, at the exposure you will be using, not zoomed-in on an extreme close up on the chart, but not too far away either, in the body of the establishing shot of your scene.
Tests can be a minor drain on your budget, but perhaps you can get your teacher to do this as a class test at school expense. Or coordinate with other students, each testing a different film stock, or testing each school camera.
TECHNICAL INFORMATION REGARDING HD TRANSFERS
Onelight vs. Bestlight vs. Scene-to-Scene Transfers
Colorlab offers three types of HD transfers with varying levels of color correction. When we process your film, we will compile your film rolls to 1,000’ lab flats in order you noted on the film cans. It is important to hand write on the cans of your camera rolls with an ascending number or letter scheme while shooting. Too many times students forget to do this, which means the lab will number them for you, but probably out of the order you intended. When this happens, there is no continuity of color when the colorist has to deal with scenes that disappear and reappear several rolls later. This can cause the same scene shot on two different rolls to look rather different when you are cutting them together in editing. If ordering a one light or best light, we DO NOT spend time going back to ‘match’ the look of the scene that comes up again later on. Even if you are ordering a scene-to-scene, it will add time to the color session and money to your bill to reconstruct the color of the scenes that are separated by the random ordering of the rolls.
- Onelight Transfer – The colorist will take each flat, setup to the first shot (which should be a gray chart but can be the first actual take), and then will let the whole flat run without stopping. If shots appear that are dramatically over or underexposed, the colorist may make changes in real-time to prevent clipping on either the highlights or lowlights but there’s no guarantee that there won’t be any clipping. The key to remember is that there is NO STOPPING of the transfer. If you don’t even want the colorist to touch the controls after his initial setup, please indicate that you want a STRICT Onelight transfer. Onelight transfers are a budget-conscious option for anyone that is willing to accept that their transfer WILL require additional color and exposure correction in post-production. They are also great for testing film stocks as you can see how the film natively reacts to different exposures and looks.
HD Framing Specs
As mentioned previously, Super-16 gives you a 1.66:1 aspect ratio which a small matte applied in the transfer can convert to 1.78:1 or 16:9. You’ll lose a slight bit of image on the top and bottom but it’s still the same basic shape. Make sure the DP knows this when he or she is composing shots to adjust for headroom. If you are shooting regular 16mm, however, you have 3 choices to make in terms of how it will be framed for HD:
- 16:9 Extraction – We give you the full image east to west but you lose 12.5% of the top and bottom for a total image loss of 25%. This is fine if your DP knows to frame for this.
Regardless of which option you choose, you need to make sure the DP keeps this in mind so that no important information gets cut, cropped, etc. It is a good idea to include a framing chart on the first camera roll so that the colorist can verify how the DP is framing the image.
1080i vs. 1080 Psf
‘Psf’ stands for progressive segmented frames and ‘I’ stands for interlaced. All standard definition video is 30 fps (29.97) in the U.S. with the discrepancy between 24 frames of film per second and 30 frames of video per second being handled by making the even video frames two fields and the odd frames three fields (each video “frame” is comprised of two fields). These extra fields added up make up the difference between 24 and 30 frames per second.
Unless you are cutting your HD transfer in with up-converted standard definition video, we would suggest going with 1080 Psf. This allows you to keep the frame rate of your camera (24 fps) with a 24 frame timecode in an ideal 1:1 ratio.
If delivering to a client, or preparing a show for broadcast, and you are unsure of the final HD format requirements, go with 1080 Psf which can be rather easily converted to any other format. The same is not true of 1080i without potential aliasing problems (smearing) and possible long and costly render times.
Standard definition video can only be up-converted to 1080i, as they both employ 30 frame timecode.
Compressed vs. Uncompressed
Fully uncompressed HD video files are extremely large and require significant hardware upgrades in order to work with in real time. As such, some HD compression codecs have been developed to provide easier use on standard hardware and editing platforms while maintaining acceptable quality. Such options we offer are Apple ProRes, ProRes HQ, DVCPRO HD, and DNX HD. The ProRes files were specifically designed for Final Cut Pro and others work just as well.
If you are unsure of what type of file you want, you should probably go with a compressed HD file over an uncompressed one. We only recommend uncompressed HD files if you are aware of the technical issues it can present and if you have the hardware to handle them.
ORDERING UNCOMPRESSED HD FILES
Now that you’ve decided you want an uncompressed HD file, there are some factors that affect the type of uncompressed HD file you have. Unless specifically requested, we will go to an HDCAM or HDCAM SR tape master first and then create an uncompressed file for you. While there is some inherent compression introduced by the limitations of the tape stock, we’re not introducing any additional compression to it when we are making the file.
If you want a fully uncompressed HD file straight from our telecine, you will need to bypass the tape master all together. Please see our section on tapless transfers. You will also need to provide sufficient hardware capable of handling sustained transfer rates of 250 megabytes per second (notice that it is megabytes rather than megabits ). A standard external hard drive has a sustained transfer rate of about 30 megabytes per second.
8-Bit vs. 10-Bit
The bit-rate refers to the depth of the sampling for each channel. In 8-bit, each time you sample a channel, you have 256 possible values whereas 10-bit offers 1,024 possible values. Think of it as two different grayscales, one with 256 different shades from black to white versus one with 1,024 different shades.
4:2:2 vs. 4:4:4
This refers to the color space of the samples. As with 4:2:2, a YUV color space uses luminance (Y) and chrominance (U and V) as components and it is used for broadcast television to compress information for faster and easier to handle media. RGB, however, uses a Red/Green/Blue color space where each of these three colors is independently sampled. You can think of it as three separate grayscales in Red, Green, and Blue. By nature, an RGB color space uses 4:4:4 sampling.
What the heck does all that mean?
The key thing to note is how large some of these HD transfer files can get. An HOUR of HD footage will result in these approximate file sizes:
8-bit 4:2:2 YUV. 448 GB’s for storage, 124 MB’s per second to transfer (i.e. use in real time)
10-bit 4:2:2 YUV. 597 GB’s for storage, 166 MB’s per second to transfer
10-bit 4:4:4 RGB. 896 GB’s for storage, 249 MB’s per second to transfer
For comparison, here are some very nice looking, easy-to-use compressed HD formats:
Apple ProRes. 60 GB’s for storage, 16.5 MB’s per second to transfer
Apple ProRes HQ. 90 GB’s for storage, 25 MB’s per second to transfer
DVCPRO HD. 53 GB’s for storage, 15 MB’s per second to transfer
Pay particular attention to the transfer rates as well. The typical external hard drive (even one that holds 1 TB of information) has a sustained transfer rate of about 30 MB’s per second. This means that you can’t really edit uncompressed HD from a simple external hard drive and we can’t transfer to your hard drive in real time. You will need some sort of a RAID unit or a collection of multiple hard drives that act as one in order to absorb and transfer that level of information in real time. A single external hard drive literally cannot spin fast enough to take in all that information.
Tape Masters and Tapeless Transfers
Colorlab strongly recommends tape-based masters to back-up all transfers. Anything can happen to a hard drive as most people can probably attest to from personal experience. Currently, Colorlab offers HDCAM and HDCAM SR as tape masters. Some specs below: