For decades now I’ve been filming stories and documentaries at Full HD 1920×1080 resolution. First with a pair of Sony HDV tape cameras, the venerable Z1 and A1, then with a pair of Canon XA-10 cameras which have been reliable, brilliantly designed and produced superb images and sound.
A few years ago I did a video review of an amazing camera, the Sony NEX FS700 digital cinema camera. It has currently been viewed 34,000 times and can be seen at https://www.youtube.com/watch?v=2HckBRsRr60
More recently I reviewed the Blackmagic Design URSA Mini 12K which is basically a cine camera on steroids, now surpassed by the 17K variant. See my video review here:
These were all serious cine cameras, able to process RAW video data and featuring extremely high quality image sensors. In various guises they have been used to produce feature films and TV series for Netflix and Amazon Prime. They are not toys as evidenced by their respective price tags. For example, the URSA MiniPro 12K retails for AUD$10,835, and that’s for the body only. Everything from the top and side handles to the shoulder brace, viewfinder, batteries and most importantly, the lenses, are all extras.
Nonetheless, having worked with 16mm movie film for years, and with 35mm stills since I was a teenager (and that’s a LONG time ago!), I kept wondering how I could get my hands on an URSA Mini of my own. Then I spotted what looked to be a truly amazing bargain on Facebook Marketplace. On offer was an URSA Mini 4K camera with many extras including four Canon lenses, four V-mount batteries and a four-battery charger. The battery charger and batteries alone retail for over $2,500 and yet the whole package could be mine for just $1,300. I think it’s called a no brainer. I bought the kit and thereby stepped onto a very steep learning curve.
Making sense of sensors and lenses
My Canon XA-10 Full HD video cameras each featured a 1/3” CMOS sensor that is 4.8mm wide by 3.6mm high, giving a total area of 17.3 mm2. By contrast, a frame of 35mm still film (ie Full Frame) is 36 x 24mm with an area of 864mm2 . My Pentax K5-II stills camera has the very common APS-C sensor at 22.2 x 14.8mm. Its sensor area is 329mm2.
Now, the URSA Mini 4K has a Super 35 sensor which at first I naively thought would be close to Full Frame size. That was not the case. I had been thinking of 35mm still film frames. Digging into it, I was reminded that, yes Super 35 is based on 35mm film but in movie cameras the film runs vertically, not horizontally. Thus the width of the frame is limited by the width of the film itself, minus the strips for perforations. Originally, 35mm movie film included a thin audio stripe. Super 35 removed that stripe to slightly increase the frame size to 22 x 11.9mm, an area of 261.26mm2.
In short, the sensor in my URSA Mini 4K is very similar to the APS-C sensor in my Pentax camera. Now the lenses that came with my URSA included a mix of Canon EF and EF-S versions, where the EF lenses are Full Frame and the EF-S lenses are designed for the smaller APS-C sensors. EF lenses will certainly work with the URSA sensor but they will effectively become about 1.5 times their designated focal length. So a 50mm lens effectively becomes a 75mm lens in the URSA.
I managed to find a pristine Canon L-series 70-200mm EF F4 zoom lens, also for a bargain price. On the URSA this is equivalent to 105 to 300m which is a very useful telephoto zoom range. Many years ago one of my fellow writers at Australian Videocamera magazine, Dr Frank McLeod, sold me a truly superb Raynox HDP 9000EX x1.8 tele-extender. This amazing piece of glass retails at around AUD$2,000 and achieves this magnification without affecting the aperture of the shot. For comparison, a Canon doubler will reduce the aperture by precisely two stops, which can be a serious limitation. So on my URSA, with its effective 105-300mm Canon lens, the extender takes it to 540mm which is a pretty serious telephoto lens.
Handling the data – Gigahertzes and terabytes.
Clearly, the Super35 sensor in the URSA is not physically huge. But is is populated with extremely high high quality sensing elements that process the data extremely efficiently. It can record at up to 4000 x 2160 pixels and record the CinemaDNG RAW data at up to 60 frames per second. The image quality is stunning. The downside is that the data rate is 265MB/second for uncompressed RAW video which means your recording media need to be appropriately huge and your computer needs to have some serious grunt to achieve good playback.
The URSA Mini 4K produces files that are actually streams of CinemaDNG still files. Imported into DaVinci Resolve, these appear on the timeline as a single CinemaDNG video file which plays smoothly and can be edited and enhanced by the immense suite of colour correction and other processing available in Resolve.
I soon discovered that editing these RAW files in Vegas Pro is not quite so simple. Vegas simply imports all of the CinemaDNG files as stills. The URSA Mini 4K was the first model in this series. In subsequent models, such as the Mini 4.6K Pro, right through to the 17K, the RAW video is stored in a new Blackmagic Design format, called BRAW. Vegas can definitely work seamlessly with BRAW files.
The workaround for me is to import the CinemaDNG video files into Resolve and work with them there, or to export them as BRAW files and then work with them in Vegas. The reason for mentioning this is that I’m still learning how to work in Resolve, but having spent 25 years working in Vegas, I’m just far more comfortable in that environment and can get from idea to finished video so much faster. Of course one positive consequence is that the individual CinemaDNG files make superb stills from your video.
CFast 2.0 cards
Later model URSA Minis have two CFast 2.0 slots for data recording as well as several other options including SDHC cards and USB-C ports. My URSA Mini 4K just has the two slots for CFast 2.0 cards. These cards are fast and come in a range of capacities up to several terabytes. The problem is that they are extremely expensive. For example, an Angel Bird AVpro XT 256GB costs $1,200 at Camera House, and a 512GB card is an astonishing $2,050.
There are cheaper cards available – not that much cheaper – but they will almost certainly not cope with the very data rates required in the URSA. What to do?
After some forensic searching I finally discovered a really good solution for storing ever larger amounts of my precious URSA video files. A Chinese company called Zitay produces an elegant solution. A blank CFast card fits into one of the slots in the URSA and is connected via a data cable to a tiny unit that houses an SSD high-speed memory card. It took some searching but I tracked down the card recommended by Zitay, which is a Samsung mSATA 860 NAND 1TB SSD. For the URSA, cards are limited to 1TB or they won’t be recognised. These cards come in several configurations but I finally found the correct one to fit the little Zitay case. It cost just $65.00, and the case, blank CFast card and cable cost just over $200.
The SSD card fits into a slot in the case and is then screwed into place and the cover attached. The little unit then screws onto any convenient socket on the camera. You can actually buy several of the 1TB SSD cards and swap them in the little case to gain even more memory capacity. Just replace the screws with Velcro tapes and the swap-over is simple and cheap.
With some trepidation I plugged in the fake CFast card and was relieved to see the camera light up immediately with the new 1TB of memory. There is an option to stop recoding after dropped frames and I turned this on to how how the system would cope. Recording at the highest level with uncompressed lossless RAW 4000 x 2160 video showed the SSD handled the data rate flawlessly. Recording time was 36 minutes on the 1TB SSD card.
A really useful high quality format would be ProRes Ultra HD at 3840 x 2160 HQ giving 92 minutes of available recording.
Dropping down to Full HD 1920 x 1080 – which is still the standard broadcast TV resolution – you get 367 minutes at HQ and a massive 547 minutes at 422 encoding.
The conclusion is simple: the Zitay SSD system, which cost just $260, works superbly and makes useful recording of even the highest resolution video affordable.
Conclusion
Cinema digital cameras like those on offer from Blackmagic Design make it possible to film extremely high quality video for a fraction of the cost that would have applied even ten years ago. The URSA Mini 4K is no exception. The later models offer even higher resolution and certainly include features that make their use even simpler but the key feature of the all of them is the stunning imagery produced by the Super 35 sensor.
When compared with the laborious workload and huge expense required to work with movie film, using the URSA Mini is child’s play. Add in the possibilities of slow motion and timelapse cinematography, all of which are easily achieved thanks to the incredibly user-friendly touch screen, and the only limit to what you can achieve is your imagination.
I once worked as Associate Producer on the IMAX feature film Australia: land beyond time. The 70mm film rolled horizontally through the gate so the frames are much wider than the film width. Each magazine holds up to 1500 feet of film but the film takes time to get up to speed and slow down, so the usable footage per load is typically just 2 minutes. That film stock alone will cost between $2,000 and $4,000 per load. Processing and the production of work prints and telecine transfers will add several thousand dollars per load. And the costs just continue add up when you include insurance and shipping for the film, not to mention that you can’t actually buy an IMAX camera; they have to be rented at thousands of dollars per day.
Given that comparison, I felt like kissing my URSA Mini 4K and racing out to make my next movie.
Dr David Smith is a film maker and author. His latest film is called Let the Shine; memorials in glass for military service from the Boer War to Afghanistan. It is available at the Department of Veterans Affairs website at:
https://anzacportal.dva.gov.au/commemoration/symbols/stained-glass-windows
David’s website is www.imaginaction.net.au
2 Comments
Great Article.
Thanks.
Dr Smith has a very good grasp of video indeed, and the mechanics that make it up.