Sony have just released the firmware required to use the new 32Gb SxS-1 cards, the Memory Stick and SD Card adapters. This firmware also adds the ability to have much longer clip titles (46 Characters!) on the PMW-350 and EX1R. You can do the update yourself, you don’t have to send the camera back to Sony (hooray) to do the update. CLICK HERE to go to the firmware on the Sony UK site. Initial reports indicate that the update improves the performance of 3rd party SD card adapters and is straight forward to install. There are also indications that original EX3?s boot up a bit faster. At the moment the EX1 update appears to be missing from the download page, but I have been assured this will be rectified in the next 24 hours.
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How I shoot the Northern Lights
Well I have just returned from Iceland where I held a couple of 3D stereoscopic master classes and a workshop on video for the internet. They went well and we all had fun despite almost a foot of snow fall the morning of the classes. On the last day of my trip I decided to try and get some more Northern Lights footage. As I am often asked how I do this I put together the clip below which explains what settings I use for the Aurora and also gives a brief description of S&Q on an XDCAM EX. Basically what I do is use the EX Slow Shutter at 32 or 64 frames to increase the sensitivity of the camera. For a dim Northern Lights display I use 64 frames but for a bright display I drop down to 32 frames. The slow shutter acts like a long exposure on a stills camera. I then combine this with interval record shooting at 1 frame every second. I did also have a Canon DSLR with me and tried to shoot the Aurora with that. I found I needed a 10 second exposure at 800 asa to get a similar result to that achieved with the EX. The 10 second exposure means that it would take longer to get a decent length video sequence and most of the motion of the Aurora would be lost. Some of the exposure difference was I admit to the slower F4 lens on the Canon compared to the Sony EX’s F1.8, so perhaps with a faster lens you could bring the exposure down to around 5 seconds and this is something I hope to try when I go Aurora chasing next winter.
If you watch the video make sure you stay to the end to check out my attempt to record a piece to camera in 60 mph blowing snow! Don’t know why I even thought it would work. What I will say is that my new Vinten 5AS did a great job of keeping the camera steady in some pretty extreme conditions.
Brewing up a Scene File: Gamma and Knee
Brewing up a Scene File: Gamma and Knee
Before anyone complains that I have missed stuff out or that some technical detail is not quite right, one of the things I’m trying to do here is simplify the hows and why’s to try and make it easier for the less technical people out there. Lets face it this is an art form, not a science (well actually a bit of both really).
So what is a gamma curve anyway? Well the good old fashioned cathode ray tube television was a very non-linear device. You put 1 unit of power in and get one unit of light out. You put 2 units in and get 1.5 units out, put 3 in and get 2 out… and so on. So in order to get a natural picture the output of the camera also has to be modified to compensate for this. This compensation is the gamma curve, an artificial modification of the output signal from the camera to make it match TV’s and monitors around the world. See Wikipedia for a fuller explaination: http://en.wikipedia.org/wiki/Gamma_correction
So, all video cameras will have a gamma curve, whether you can adjust it or not is another matter. Certainly most pro level cameras allow you some form of gamma adjustment.
The PMW-350 has 6 standard gamma curves, these are all pretty similar, they have to be otherwise the pictures wouldn’t look right, but small changes in the curve effect the relationship between dark and bright parts of the pictures. Todays modern cameras have a far greater dynamic range (range of dark to bright) than older cameras. This means that the full dynamic range of the sensor no longer fits within the gamma curves used for TV’s and monitors. In broadcast television any signal that goes over 100% gets clipped off and is discarded, so the cameras entire brightness range has to be squeezed into 0 to 100%. The PMW-350 sensors are capable of far more than this (at least 600%) so what can you do?
The older and simpler solution is called the “Knee”. The knee works because in most cases the brightest parts of a scene contains little detail and is generally ignored by our brains. We humans tend to focus on mid-tone faces, animals and plants rather than the bright sky. Because of this you can compress the highlights (bright) parts of the picture quite heavily without it looking hugely un-natural (most of the time at least). What the knee does is takes a standard gamma curve and up near it’s top, bends it over. This has the effect of compressing the brighter parts of the image, squashing a broad range of highlights (clouds for example) into a narrow range of brightness. While this works fairly well, it does tend to look rather “electronic” as the picture is either natural (below the knee) or compressed (above the knee).
The answer to this electronic video look is to replace the hard knee with gentle bend to the gamma curve. This bend starts some way down the gamma curve, very gentle at first but getting harder and harder as you go up the gamma curve. This has the effect of compressing the image gently at first with the compression getting stronger and stronger as you go up the curve. This looks a lot more natural than a hard knee and is far closer to the way film handles highlights. The downside is that because the compression starts earlier a wider tonal range is compressed. This makes the pictures look flat and uninteresting. You have to watch exposure on faces as these can creep into the compressed part of the curve. The plus point is that it’s possible to squeeze large amounts of latitude into the 100% video range. This video can then be worked on in post production by the editor or colorist who can pull out the tonal range that best suits the production.
These compressed gamma curves are given different names on different products. Panasonic call them “Film Rec”, on the EX1 they are “Cinegammas” on the PMW-350 they are “Hypergammas”. The 350 has four Hypergammas. The first is 3250. this takes a brightness range the equivalent to 325% and compresses it down to 100%. HG 4600 takes 460% and squeezes that down to 100%. Both of these Hypergammas are “broadcast safe” and the recordings made with them can be broadcast straight from the camera without any issues. The next Hypergamma is 3259. This takes a 325% range and squeezes this down to a 109% range, likewise 4609 takes 460% down to 109%. But why 109%? well the extra 9% gives you almost 10% more data to work with in post production compared to broadcast safe 100%. It also gives you the peak white level you need for display on the internet. Of course if you are doing a broadcast show you will need to ensure that the video levels in the finished programme don’t exceed 100%.
My preferred gamma is Hypergamma 4 (4609) as this gives the maximum dynamic range and gives a natural look, however the pictures can look a little flat so if I’m going direct from the camera to finished video without grading I use either a standard gamma or use the Black Gamma function to modify the curve. I’ll explain the Black Gamma in my next post.
There are 6 standard gammas to choose from. I like to stick with gamma 5 which is the ITU-709 HD standard gamma. To increase the dynamic range I use the Knee. The default knee point setting is 90, this is a reasonable setting, but if your shooting with clipping set to 100% you are not getting all the cameras latitude (the Knee at 90 works very well with clipping at 108%). Lowering the knee down to 83 gives you almost another stop of latitude, but you have to be careful as skin tones and faces can creep up towards 83%. It’s very noticeable if skin becomes compressed so you need to watch your exposure. This is also true of the Hypergammas and with them you may need to underexpose faces very slightly. The other option is to set the knee point to 88 and then also adjust the knee slope. The slope is the compression amount. A positive value is more compressed, negative less compressed. With the knee at 88 and slope set to +20 you get good latitude, albeit with quite highly compressed highlights.
If you want to play with the gammas and knee and see how they work one method you can use is to use a paint package on your PC (such as photoshop) to create a full screen left to right graduated image going from Black to white. Then shoot this with the camera (slightly out of focus) while making adjustments to the curves or knee and record the results along with a vocal description of each setting. Import the clips into your favorite editing package and use the waveform monitor or scopes you should be able to see a reasonable representation of the shape of the gamma curve and knee.
So my Gamma Choices are:
For material that will be post produced: Hypergamma 4609 (HG4)
For material that will be used straight from the camera: Standard Gamma 5 Knee at 90 with clip at 108% for non broadcast or Knee at 88 with slope +20 with white clip at 100% for direct to broadcast.
PMW-350 Aperture Correction what is it doing?
After completing the multi camera shootout at Visual Impact, one thing was bothering me about the pictures from the PMW-350 and that was the way the specular highlights in the tin foil were artificially enhanced. During the test the camera was set to factory defaults, which IMHO are too sharp, but the foil in particular looked nasty. Since then I have been further refining my paint settings for the 350 and looking at detail and aperture. Today I was replicating the tin foil test and looking at the aperture settings (not the knee aperture) and I noticed that turning aperture on and off had a very pronounced effect on highlights but a much smaller effect elsewhere in the image. Normally I would expect the aperture setting to act as a high frequency boost making subtle textures more or less enhanced, which it does, but the amount of enhancement appears to vary with the brightness of the image with specular highlights getting a really big hit of correction. If you look at the images to the left at the top you have aperture correction on at +99. There are big ugly black lines around the highlights on the foil and the texture of the carpet has been enhanced. To some degree this is the expected behaviour although I am surprised by how thick the edges around the highlights are, this looks more like detail correction (it could be “ringing”). The middle images are aperture off, not zero but actually off and you can see that the edges on the foil have gone and the carpet is no longer enhanced. The bottom picture though with aperture on at -99 though is very interesting as the carpet appears slightly softer than OFF, which is not unexpected while the foils is sharper than OFF and this is not expected. I don’t like this behaviour I’m afraid to say as a typical way to get a filmic look from a video camera is to turn the detail correction off to give a natural picture and then use Aperture correction to boost high frequencies to retain a sharp image. On the PMW-350 you can’t do this as this as a high Aperture setting will give you those nasty edges on highlights. So what can you do? Well the 350?s native, un-enhanced resolution is very high anyway so it doesn’t need a lot of correction or boosting. The default Detail and Aperture settings will give some really nasty highlight edges so you need to back things off. If your going for a filmic look I would turn OFF aperture correction altogether, for video work with pictures that have some subtle enhancement I would use Aperture at around -20, certainly never higher than -15 unless you like black lines around specular highlights.
My current prefered detail, aimed at giving a very slight, not obvious enhancement are are as follows:
Detail Level -12, H-V Ratio +15, Crispening 0, Frequency +30, White Limit +30, Black Limit +40 (all other detail settings at default)
Aperture OFF for filmic look, Aperture -20 for video look.
I have also made some changes to the Matrix settings. I have been finding the pictures from Sony cameras to be a little on the Green/Yellow side so I have tweaked things a little to remove the yellow cast and put in a bit of red, this is a subtle change but really helps with skin tones, stopping on screen talent from looking ill! These settings work in the PMW-350, EX1/3 and PDW-700.
On an EX1/EX3 this works best with the Standard Matrix, On a PMW-350 or PDW-700 you can use it on it’s own or mix it with one of the preset matrices as a modifier. User Matrix On, R-G 0, R-B +5, G-R -6, G-B +8, B-R -15, B-G -9
Have Fun!
PMW-350 sample footage from Norway
I have uploaded a further selection of clips from the PMW-350 shot in Norway to YouTube. It’s also on Exposure Room if you want better quality.
What is “Crispening” and how does it effect the picture?
What is “Crispening” and how does it effect the picture?
Crispening is one of the adjustments you can make in many of Sony’s video cameras that adjusts the way the image is sharpened via the detail correction circuit. On an EX1 or EX3 it is in the Picture Profiles section. If use wisely Crispening can be used to help deal with camera noise by making it less visible, thus giving a cleaner image. Crispening works across the entire luma (brightness) range. It’s really difficult to explain how the level adjustment works, it is a threshold adjustment for the detail circuit, but I’ll have a go anyway.
First off lets consider how the detail circuit works. The camera uses delay circuits to compare how the brightness (luma) levels of adjacent pixels are changing, both from left to right and line by line. If the circuit sees a rapid change from light to dark or dark to light (or light to lighter, dark to darker etc) the circuit regards this as an edge and detail correction is applied by brightening or darkening the transition, exaggerating the edge. This is seen in extreme cases as a black or white halo around edges.
On the EX cameras crispening works by adjusting the threshold at which the light to dark transition between pixels triggers the application of detail correction. So when you set a negative number, say -99 even the slightest luma difference between pixels will have detail correction applied. Set it to +99 and it takes a much greater luma change to trigger the detail circuit.
What you need to understand is that if you set crispening such that the threshold before detail is applied is 100mV (for example) then between 0v (black) and 99mV little to no detail correction will be applied, keeping blacks clean by not applying detail correction to any noise with an amplitude less than 100mV. But if there are subtle textures in the image, going say from 500mV to 599mV (mid tones) then no detail correction will be applied here either, so the image will appear a little softer, only larger luma changes of more than 100mV will have detail correction applied. These small luma changes can be anywhere within the full luma range and it is not confined just to the darker parts of the image.
Raising the crispening level setting to a positive number raises the threshold at which detail is applied to the image, so a high number prevents detail correction from being added to small luma changes. A negative number means that detail correction will be applied to smaller luma changes, this increases the appearance of noise but also makes textures appear sharper.
One thing to consider is that the noise the camera produces is not only in the blacks. If the noise amplitude (level) is for example 5mV, then if you have a subject at 500mV (mid tones) it will still have random 5mV noise added to it. It just tends to be that noise is most visible in the blacks as 5mV of noise on a 5mV (very dark) signal is modulating (varying) the signal by 100% so it’s quite obvious, however 5mV on top of 500mV is only 1% so less obvious, but still there and still visible.
You should remember that the cleaner you can make the recorded image the less stress there is on the codec. This in turn means less mosquito noise and macro blocking giving an image that looks cleaner still and grades better. I struggle to see the difference between crispening at 0 and at +20 in most normally exposed shots, but if I look closely I do see less noise in shadow and low contrast areas. Low contrast areas tend to have little detail anyway, so being able to clean these up a little helps in post production.
Sony have a PDF about it here:?http://www.sony.co.uk/res/attachment…6605183226.pdf
Just how big is the 3D market?
As you walked around the BVE show in London last week you could not help but notice that just about every stand had some kind of reference to 3D production. The impression given was that 3D is here, it is going to be huge and everyone needs to be able to shoot in 3D. But is this really the case? Certainly there has been a big increase in the number of 3D movies produced in the last 18 months and Avatar is now the largest grossing movie ever made, much of the profits coming from 3D screenings. Sky TV in the UK are starting a 3D TV channel later in the year and Discovery, ESPN and others have announced their intentions to launch stereoscopic channels. To add to all this the TV manufacturers are also bringing large ranges of 3D TV’s to market.
But before you all rush out and spend large sums of money on expensive 3D camera rigs you need to look more closely at what’s going on and consider who will actually want to watch 3D. Now I am a fan of 3D, don’t get me wrong and I do believe that 3D is here to stay, but as I see it, until display technology finds a way to eliminate the need to wear special glasses 3D is going to be reserved for special events, movies and spectaculars. Lets face it who’s going to want to have to put on a pair of glasses after a hard days work, just to watch the news or a soap. This is supported by Sky’s recent 3D seminar where they stated that they are only looking at showing 4 hours of new 3D programming every week and the only things they are looking for are movies, major sporting events, special events and one off, mega specials – “planet earth” type big budget docs. The rest of the week will be repeats and re-runs. So, in the UK it’s likely that there will be a couple of OB trucks kitted out for 3D for sports and other events filing a couple of hours a week leaving just two hours which will be split between docs, specials and movies.
Now Sky 3D won’t be the only outlet for 3D in the UK. There will be some corporate productions with budgets big enough for 3D and there will be a market for a few on-demand specialist channels and 3D BluRay’s and DVD’s but the really big market will be the 3D games market. Even so for most production companies, 3D could be an expensive mistake. Investing in expensive 3D rigs, pairs of cameras, 3D production monitors and edit systems won’t be cheap. In addition there is a whole new set of skills to be learnt, shooting 3D is very different to 2D. Perhaps (sadly) the real future of 3D TV lies not with true 3D capture and filming but with clever boxes like the JVC IF-2D3D1 2D to 3D converter which can take existing 2D material and convert it in to pretty convincing 3D for the price of a single pro camcorder. It may even be that one day all home TV’s will contain a similar converter and you will be able to watch whatever you want in Pseudo 3D at the press of a button.
So back to the original question, how big is the 3D market? Well I think it’s actually pretty small, probably best left to a few specialist production companies or 3D consultants and facilities companies. Certainly lots of 3D TV’s will get sold to affluent techno geeks and home cinema enthusiasts, but lets face it, HD was a hard sell and you don’t need glasses for that.
NextoDI Demonstrate writing to BluRay from NVS2500
At the recent BVE show in London, NextoDI were showing a demo of what will be available in the next firmware release, due around NAB time. The most significant feature is the ability to archive your material directly from the NVS2500 to BluRay!
You will be able to plug the NVS2500 into a USB BluRay burner and burn your files from the NextoDI straight on to BD-R discs!
So, no need for a computer or BluRay software, just the NextoDI and a BD burner. This makes the NVS2500 a truly pivotal device. You take your rushes in the feild, back them up on to the 2500, then plug in a BD writer and produce your archive discs. Remember that BD-R should have a shelf life of around 25 years. It doesn’t tie up a computer and there’s no reason why you couldn’t do this on location, the recommended LG drive even runs off 12v so you could do it in a car or running off another 12v battery.
As well as writing to BluRay the new firmware will also have the ability to recover some types of corrupt clips. To be honest, if you use SxS this should not be a problem, but it’s a useful tool to have. It will also reject bad sectors when writing to a hard drive thus reducing the risk of errors in the first place.
I know the NVS2500 is not the cheapest piece of kit on the planet, but it really, really, really is worth every penny. If you took mine away from me now it would be like cutting off an arm. It is one piece of the whole file based jigsaw that has really made my life so much simpler, faster, less stressful.
10/10 product, fantastic, excellent….
NextoDI Demonstrate writing to BluRay from NVS2500
At the recent BVE show in London, NextoDI were showing a demo of what will be available in the next firmware release, due around NAB time. The most significant feature is the ability to archive your material directly from the NVS2500 to BluRay!
You will be able to plug the NVS2500 into a USB BluRay burner and burn your files from the NextoDI straight on to BD-R discs!
So, no need for a computer or BluRay software, just the NextoDI and a BD burner. This makes the NVS2500 a truly pivotal device. You take your rushes in the feild, back them up on to the 2500, then plug in a BD writer and produce your archive discs. Remember that BD-R should have a shelf life of around 25 years. It doesn’t tie up a computer and there’s no reason why you couldn’t do this on location, the recommended LG drive even runs off 12v so you could do it in a car or running off another 12v battery.
As well as writing to BluRay the new firmware will also have the ability to recover some types of corrupt clips. To be honest, if you use SxS this should not be a problem, but it’s a useful tool to have. It will also reject bad sectors when writing to a hard drive thus reducing the risk of errors in the first place.
I know the NVS2500 is not the cheapest piece of kit on the planet, but it really, really, really is worth every penny. If you took mine away from me now it would be like cutting off an arm. It is one piece of the whole file based jigsaw that has really made my life so much simpler, faster, less stressful.
10/10 product, fantastic, excellent….
More PMW-350 Demo Footage.
I have uploaded a further selection of clips from the PMW-350 shot in Norway to YouTube. It’s also on Exposure Room if you want better quality.