First let me say that as yet I have not used C-Log in anger, only seen it at a couple of hands on demo events and in downloaded clips.
From what I’ve seen C-Log and S-Log are two quite different things. S-Log on the F3 is a true Log curve where each stop of exposure is recorded using roughly the same amount of data and the available dynamic range is about 13.5 stops. It is inevitable that when you use a true log curve like this and play it back on an uncorrected Rec-709 (standard HD gamma) monitor that it will look very flat and very washed out. This is a result of the extreme gamma miss-match across the entire recording range. If you had a monitor that could display 13.5 stops (most only manage 7) and the monitor had a built in Log curve then the pictures would look normal.
What has too be considered is that S-Log is designed to be used with 10 bit recording where each stop gets roughly 70 data bits ( this roughly means 70 shades of grey for each stop).
Now lets consider the Canon C300. It has no 10 bit out, it’s only 8 bit. Assuming Canon’s sensor can handle 13.5 stops then using 8 bit would result in only 17 bits per stop and this really is not sufficient, especially for critical areas of the image like faces and skin tones. A standard gamma, without knee, like Rec-709 will typically have a 7 stop range, this is a deliberate design decision as this yields around 34 bits per stop. As we know already if you try to do a hard grade on 8 bit material you can run in to issues with banding, posterisation and stair stepping, so reducing the bits per stop still further (for example by cramming 13.5 stops into 8 bits) is not really desirable as while it can improve dynamic range, it will introduce a whole host of other issues.
Now for some years camera sensors have been able to exceed 7 stops of dynamic range. To get around the gamma limitation of 7 stops, most good quality cameras use something called the knee. The knee takes the top 15 to 20% of the recording range to record as much as 4 to 5 stops of highlights. So in the first 0 to 80% range you have 6 stops, plus another 4 to 5 stops in the last 20%, so the overall dynamic range of the camera will be 10 to 11 stops.
How can this work and still look natural? Well our own visual system is tuned to concentrate on the mid range, faces, foliage etc and to a large degree highlights are ignored. So recording in this way, compressing the highlights mimics they way we see the world, so doesn’t actually look terribly un-natural. OK, OK, I can hear you all screaming… yes it is un-natural, it looks like video! It looks like video because the knee is either on or off, the image is either compressed very heavily or not at all, there is no middle ground. It’s also hard to grade as mid tones and highlights have different amounts of squashing which can lead to some strange results.
So the knee is a step forward. It does work quite well for many applications as it preserves those 34 bits of data for the all important mid tones and as a result the pictures look normal, yet gives a reasonable amount of over exposure performance. Next came things like cine gammas and film style gammas.
These often share a very similar gamma curve to standard gammas for the first 60-70% of the recording range, so faces, skin, flora and fauna still have plenty of data allocated to them. Above 70% the image becomes compressed, but instead of the sudden onset of compression as with a knee, the compression starts very gently and gradually increases more and more until by the time you get close to 100% the compression is very strong indeed. This tends to look a lot more natural than gamma + knee, yet can still cope with a good over exposure range, but depending on the scene it can start to look a little flat as your overall captured range is biased towards highlights, so your captured image contains more bright range than low range so will possibly (but not always) look very slightly washed out. In my opinion, if shooting with cinegammas or similar you should really be grading your material for the best results.
Anyway, back to the Canon C300. From what I can tell, C-Log is an extension of the cinegamma type of gamma curve. It appears to have more in common with cinegammas than true S-log. It looks like the compression starts at around 60% and that there is a little more gain at the bottom of the curve to lift shadows a little. This earlier start to the compression will allow for a greater dynamic range but will mean fewer bits of data for skin tones etc. The raised lower end gain means you can afford to underexpose more if you need to. As the curve is not a full log curve it will look a lot more agreeable than S-Log on an uncorrected monitor, especially as the crucial mid tone area is largely unaffected by strong compression and thus a large gamma miss-match.
For the C300 this curve makes complete sense. It looks like a good match for the cameras 8 bit recording giving a decent dynamic range improvement, largely through highlight compression (spread over more recording range than a conventional knee or cinegamma), keeping mid tones reasonably intact and a little bit of shadow lift. Keeping the mid range fairly “normal” is a wise move that will still give good grading latitude without posterisation issues on mid range natural textures.
I’d just like to wish all my readers a very happy Christmas. Thanks for the support and kind words I received from many of you over the year.
Next year promises to be an exciting one, there will be new cameras to play with, firmware updates and gadgets galore. I will be running workshops across the world, starting straight after the Holidays in Korea and JeJu. Mid Jan I have a 3D workshop at ProKit in London, then it’s off to Norway for my Northern Lights expedition where I will hopefully stream near live Aurora images. Feb looks like a visit to the USA for more workshops and so it continues. I have most of May booked out next year for Tornado chasing assignments in the USA and a couple of interesting film projects on the cards.
I hope you all have interesting and exciting things to look forward to next year. I know time are tough for many right now, perhaps if your not so busy it’s a good time to learn some new skills or hone existing ones, after all it’s your skills that will make you stand out from the crowd, not the technology that you may or may not own.
So have a happy holiday season, I’ll have more stuff for you to read after a short break.
I’m off to Norway to shoot the Northern Lights in a months time. I will be trying to feed near real-time images of the Aurora via this web site. There will be a page dedicated to the project and weather and technology permitting you should be able to view snapshots of the Aurora as I capture them.
Once again I’m having server problems. My domains are being moved to a new more powerful server, cos you lot keep reading my stuff 😉
I apologise if when you come to look for something you find the site down. Hopefully this move will mean better performance and better up-time. Please rest assured that everything is backed up, so should a complete disaster occur during the move, I will be able to restore normal service asap.
I was asked if I could come up with a Log style profile for the sony FS-100. Well here are the settings for a very flat almost log look. Grading will be essential:
AC-FS-Log
Gamma Cinematone 1
Black Level: -1
Black Gamma: High, +7
Knee: 85
Color Mode: Standard, -3
Color Level -4
Detail-4
Last night was a big deal. 12 PMW-F3’s shooting the legendary pop band Duran Duran. Back in the 80’s DD were one of the first bands to embrace the video age with ground breaking, big budget films to accompany their top 10 singles that were very different to anything done before. I have to admit I was and still am a big fan. Back in April, I had a discussion with my good friend Den Lennie about possibly shooting a Duran Duran concert with F3’s. That led to a trip to Berlin in May to shoot the band at a small concert, however, lead Singer Simon LeBon had vocal problems and the entire tour got postponed at the last  minute.
F3 and Optimo 24-290 rigged in Berlin for the concert that never happened.
We were fully rigged at the venue, ready to go when we got the last minute call that it was off. This was very disappointing. Despite a second attempt to stage the show, it never went ahead and that was about the last I heard.
Being a Duran fan, I went to see them in concert at Birmingham about 2 weeks ago. It was a fantastic gig and the whole family had a great night out. As I watched the amazing light show, I thought to myself that it was a great shame that this was not being recorded.
Then almost out of the blue I get a phone call from Den Lennie and James Tonkin of Hangman Studios. The question was… Did I think we could shoot a Duran Duran concert with just 7 days to prepare? Of course I said yes and having seen the show, I recommended that we should try to make it happen. So James and Den got together with Director Gavin Elder who has been working with Duran Duran since 2003 and the magic started to happen. Just 48 hours latter I got a message from Den to say we were on! My task was to look after most of the technical aspects of the shoot, things like camera settings, picture profiles etc.
Now, I could tell you all about the tech issues that we discovered during the recce we did when we went to a gig at the O2 arena in London, but sadly you’ll have to wait. Den, James, Gavin and myself will be doing a full write up of how we made the choices we made and some of the many challenges that a concert shoot with super 35mm cameras throw up. I can tell you, it’s not as easy as a traditional OB, not in any way. But when you start pairing up Sony F3’s with 1000mm, yes 1m, lenses, beautiful Arri Alura 18-80mm and Optimo 24-290mm lenses, shooting an incredibly dynamic light show at a massive sell-out arena concert, I think you can see why this project was so exciting!
A pair of F3's with Optimo 24-290's and NanoFlashes on O'connor heads.
Everyone pulled out all the stops. Changes were made to the gig lighting and I created a picture profile to match. Audio was worked to perfection and the band put a massive amount of extra energy into the performance with the end result of an electrifying atmosphere and from what I’ve seen so far, jaw dropping images. This is one of those incredibly rewarding projects that I’ll remember for a long, long time.
Den and James did an incredible job organising kit lists, camera plans and crew lists. I’m sure they will tell their own story in due course.
James Tonkin checking out on of the 12 F3's.
It’s interesting to note that as DoP, Den’s main role was an organisational role and this is something often forgotten, a Director of Photography is not just a cinematographer, but also an organiser, arranger, overseer of the cinematography. I think the term DoP is often miss-used these days often simply being used as a fancy term for cinematographer or camera operator. A true DoP does not shoot, the camera operator does that. The DoP, directs the camera operators and directs the lighting crew to produce images to his or her satisfaction.
The final Duran Duran film is going to be distributed many ways, some of which I’m really excited about, but I can’t say more at this time. I hope you will all get a chance to see it. At this stage it is still to be edited, graded etc. James and Gavin will be working hard overseeing that stage of the production.
Me, at my camera just before the start of the set.
My role.. camera setup, creating a custom picture profile, helping on lens and kit choices, on site tech support and then operating one of the two PMW-F3’s using a B4 to s35mm adapter along with big ENG zooms. I used one of the MTF B4 to s35 adapters that I designed along with a Canon 10 to 400mm zoom. When you add the 2.5x magnification factor of the adapter system that equates to a 25mm to 1000mm zoom. My role was to shoot the close ups of lead singer Simon LeBon from the Front of House area, 160ft from the stage. With such a long lens the DoF was tiny and the shoot was hard work, but incredibly rewarding.
I promise that there will be a much more in depth write up in the future from Den, James and myself covering all aspects of the project as well as a full behind the scenes video (we had a crew shooting BTH footage). Watch this space!
It’s taken me a while to finish this review as I’ve been pretty busy. While preparing it I posted various frame grabs that I pulled from the Samurai and the Gemini on a couple of blogs and forums and these have created a bit of a stir that was never intended.
Anyway, what about the Samurai? Well to be honest I was impressed before I had even turned it on. When you buy a Samurai, not only do you get a neat little video recorder, but you also get a flight case full of everything you need to use the recorder (with the exception of a hard drive or SSD). The flight case contains the Samurai itself, a couple of adapter cables to go from the mini BNC’s to full size BNC sockets. A couple of batteries, a neat dual channel charger, a pair of drive caddies and a docking station for off loading your material. Everything is well made.
SIMPLICITY
One of best bits about the Samurai is that it is extremely simple to use. A push button on the side turns it on and your quickly greeted with the home screen. From this one screen you can record clips, enter playback mode, go in to monitor mode, format a drive, turn on timecode triggering and choose whether your progressive files get tagged as interlace or progressive (more about that in a bit).
MEDIA:
For my tests I used a 250Gb 2.5″ hard drive that I had kicking around. I’m not a fan of using spinning discs to record on, but in terms of cost per GB they are very affordable. The discs spin at between 5,400 and 7,200 rpm and this means there are some quite high gyroscopic forces in play. Twist the unit too fast or drop it and you may damage the disc leading to the loss of valuable material. The Samurai though, can also use SSD’s (Solid State Drives) which are very fast, cost effective memory devices with no moving parts. If your going to be bumping your Samurai around an SSD is the way to go, but if you need lots of cost effective storage a hard drive may work better for you, provided your sensible with it. One recommendation of my own is not to be tempted to use one big 750GB hard drive, but instead to use several 128GB or 250GB drives. This way if a drive is lost or does fail you don’t loose quite so much. While you should, as I did, be able to use pretty much any drive, there are a few that Atomos do not recommend. Atomos regularly test new drives as they become available and they provide a list of recommended hard drives and SSD’s. It’s almost certainly best if you choose your drives from the list, which can be found here.
SETUP:
There are very few menu settings on the Samurai and this makes it simple to use and fast to set up. If your using a camera with “record run” timecode the Samurai can be set to watch for rolling timecode and as soon as it does go in to record. I found a 2 or 3 frame delay between the camera going into record and the Samurai triggering, which is noting at all and in most cases you’d probably never realise there was this minute delay. Of course you can also press the big red record button on the touch screen LCD or if you have a camera with LANC you can plug a LANC controller into the Samurai and then plug the Samurai into the camera. The remote would then trigger both units together.
PsF:
One of the buttons on the home screen turns on and off PsF recording. PsF is the method used to send 1920×1080 progressive footage via HDSDi. PsF is used by just about every 1080P camera. It’s clever because it allows you to plug a progressive camera into an interlace monitor, and everything still works just fine. It does this by taking the progressive image and splitting it into 2 fields before passing it down the cable. So to the receiving device (monitor, tv, recorder etc) it looks like an interlace signal, but as there is no temporal (time) difference between the two fields, when shown on an interlace monitor what you end up with is a progressive image. The issue with this is that when you feed something like the Samurai with a PsF signal,it can’t tell whether it’s getting a progressive image split into fields or a real interlace image with two fields. This is where the Samurai’s PsF button is useful as it allows you to tell the Samurai whether the signal is progressive or interlace so that the recorded clips are correctly flagged. A word of CAUTION about this. If you are at all unsure, it is safer to not flag the clips as PsF. Why? well once a clip is flagged as PsF your edit software will always treat the odd and even lines within the frame as occurring at the same moment in time, so any effects or renders will also be progressive and this may result in motion artefacts. If you have a PsF clip flagged as interlace this problem does not occur as generally if you render from interlace to progressive the fields get combined anyway.
POWER AND BUILD:
Moving on… On the back of the Samurai are locations for 2 Sony NP series batteries. These are really common batteries that can be purchased very cheaply. Atomos will also provide you with a free D-tap adapter if you wish to take power from a 12v battery. To get the adapter all you need to do is to register your Samurai on the Atomos web site. You can also by additional adapters and a power supply from you Atomos dealer. The batteries can be hot swapped so in theory you could shoot forever, or at least until you drive is full.
The build quality is very good. The bulk of the unit is machined from aluminium, so it should take the general bumps an knocks of professional use. There is a 1/4″ threaded mount on the top and bottom of the chassis for mounting. HDSDi Input and output is via mini BNC connectors and Atomos provide you with a couple of adapter cables that go from a mini BNC plug to a standard BNC socket. While this works OK, on the review sample the connectors were straight and as a result these rather thin connectors stick out quite a long way. I don’t like this, they look a bit vulnerable to me. Atomos tell me that are looking into right angle connectors and this would be a big improvement in my opinion. The touch screen also acts as a monitor so you can check that you have not got the camera overlays turned on by mistake. Some external recorders don’t have a monitor and I’ve heard horror stories of entire shoots being ruined because the operator didn’t realise that the camera data was getting recorded burnt into the video clips. It’s not the brightest of screens and perhaps lacks a little contrast, I think some of this is due to the membrane used for the touch screen, but it’s very useable. I could probably benefit from some kind of hood in bright conditions.
BENEFITS AND IMAGE QUALITY:
Crop from frame of leaves blowing in wind, recorded using F3's internal 35Mb/s codec.
So why do you need an external recorder, most cameras are capable of producing a good image without an external recorder aren’t they? Well in general, yes, most cameras will produce an acceptable, first generation image. But when you start making multiple copies or doing extensive post production work on the internal recordings, very often they simply aren’t up to the task. Take a look at the frame grabs presented here (click on them to view full size), one recorded internally on the F3 at 35Mb/s and the other on the Samurai using ProRes HQ at approx 185Mb/s.
The same frame as above but recorded using ProResHQ on the Samurai
When you look at the unprocessed, 1st generation frames, it is perhaps hard to see a difference, but when you do just a little bit of post production grading then the difference becomes much more noticeable. The crop is of the top right part of the frame. The tree branches were blowing in the wind and this motion makes the codec have to work quite hard. When there is only 35Mb/s of data to play with the codec really struggles, while the extra data available to the ProRes codec of the Samurai means that the codec isn’t struggling at all. The other thing in this example is that the F3’s internal recordings (like most AVCHD or Mpeg2 cameras) use only 8 bits of data and the colour is sampled 4:2:0. The Samurai is 10 bit, 4:2:2.
MORE BITS ARE BETTER:
With an 8 bit recording you only have 235 brightness levels. That’s fine if you don’t manipulate the image in any way, but if you modify the image contrast or brightness you will create gaps and jumps between those steps and this will appear as banding in your pictures. 10 bit recordings have 940 brightness levels, so any steps will be much, much smaller so banding after adjusting brightness and contrast is significantly reduced and is not normally visible.
When you compare 4:2:0 against 4:2:2, the later has twice as much colour detail than the former. Now I have to confess that I often to struggle to actually see this difference in progressive material, but if you shoot interlace you can see a difference. In either case, having more colour detail will once again improve the flexibility of your material in post production and can give a small improvement in the appearance of chroma noise.
NOISE AND MACRO BLOCKING:
Talking of noise…. if you choose to look closely at the frame grabs I have provided then you may think that the recordings from the F3 have less noise than the Samurai. Well, they do and they don’t. You won’t see as much fine grain noise in the 35Mb/s frame grabs as the Samurai frame grabs because the F3’s internal codec has to discard a lot of picture information to fit it into 35Mb/s. One of the things that gets discarded is noise, but as well as noise there is also a loss of some subtle fine textures. So be careful when you look at the images, the F3 material may look cleaner, but it’s also lacking the fine detail and texture that has been captured by the Samurai. Check out the video below. First you see the full frame clips from the F3 and Samurai, ungraded and then graded. Finally you’ll see crops from the clips. Check out the ugly, blocky artefacts from the F3’s internal recordings on the first clip, then the breakup of the leaves in the second clip and finally the strange wobble of the hedge and bricks in the last shot. These are all typical motion artefacts from the long GoP Mpeg 2 used by the F3 internally.
Please watch the clip full frame 1920×1080. Please also consider that youtube adds a lot of artefacts of it’s own, but the side by side clips will be affected equally. Try pausing the clip during the side by side branches clip.
These may seem trivial in a highly compressed web clip, but let me assure you they are plainly visible on my 42″ TV. When I did compare the Samurai to the Convergent Design Gemini which is a fully uncompressed recorder there was not a lot between them. The Gemini does produce a slightly better image as it has the capability of recording a pristine, mirror image of what comes out of the camera, there is no compression, no loss, no artefacts and if quality is your absolute priority this should be the type of recorder to consider. But the Gemini produces some very, very big files that will need to be backed up and stored. For example an hour of material from the Gemini requires 750GBs worth of the very fastest SSD drives. A 750GB hard drive in the Samurai costs less than 1/10th of the price and will record over 16 hours of material. Not only that but you can backup 16 hours of Samurai material in around the same time as it would take to backup 1.5 hours of Gemini material. In terms of image quality I would say that the Samurai is more than adequate for most types of production, so you do have to ask yourself whether the small quality improvement you can get from the Gemini justifies the more expensive, more complex and slower workflow? Me personally, I’m seriously considering the Samurai as my recorder of choice for all my day to day production work. I’ve looked at the Pix-240 and it’s just too big and bulky, the Ki-Pro mini doesn’t have a monitor and the NanoFlash is only 8 bit. The Samurai ticks all the right boxes. However, if I have a big screen, high end production where the more complex Gemini workflow is not an issue, then for those productions I would use the Gemini. It’s horses for courses, the right tool for the job.
CONCLUSIONS:
For the money the Samurai is all but impossible to beat. Lets face it, the price is very good. Sometimes a price can be too low, I often associate cheap prices with sub-standard products. While the price is low, the Samurai however is not sub-standard. It’s well put together, very capable and has good recording media flexibility with the option to choose codecs (ProRes or DNxHD) and media types (SSD or HDD). With the PMW-F3 it can be used with standard gammas or 422 S-Log. It brings a significant improvement to the quality of the images you can record and makes the workflow even easier than when your using SxS (no need to re-wrap from MP4 to .mov with FCP). I think its great as an all-round every day recorder. 9/10
As you may know I’m preparing a review of the Atamos Samurai as well as the Convergent Design Gemini. Both excellent devices, but suited to different applications. If your wondering why you need an external recorder, below are a couple of crops from some footage that I shot today on the F3. High compression codecs can struggle when there is a lot of motion in the frame. What you see in the pictures below is some leaves on a tree blowing in the wind, one frame from the F3’s internal recordings and the other from the ProRes HQ from the Samurai. The clips were graded, as it was shot using S-Log, but this is a quite realistic scenario and with TV’s getting bigger and bigger, this kind of thing is getting much more noticeable.
I’ve just added integration for the TapaTalk app for the iPhone, iPad and Android devices. It’s a great app for viewing and contributing to online forums. Just download and install the app. You’ll find the forum under the “Entertainment”, “Audio Visual” section.
Cinematographer and film maker Alister Chapman's Personal Website
