Hurricane Rig FAQ’s
Q: Why not use a twin lens camcorder to shoot S3D
A: A professional twin lens camcorder is going to be considerable investment. Many production companies already have one or two suitable camcorders so the overall investment needed is a lot lower. In addition the fixed lens separation of most twin lens camcorders restricts the range of scenes and subjects that can be shot, so they are less flexible. It’s very common to shoot S3D with the cameras set to just 30mm separation! The Panasonic 3DA1 has a lens separation of approx 3.5″ (70mm) so this restricts it’s use (for good 3D) to subjects that are between around 12ft (4m) and 40ft (12m) away. A mirror rig does not have this same limitation as the camera separation can be adjusted all the way down to zero if necessary. Typically large screen 3D productions will use interaxials (lens separation) of between 1″ and 2″ (25-50mm).
Q: Why do I need a mirror rig, why can’t I just mount two cameras side by side?
A: For some subjects, such as scenic panoramas or distant objects you can use side by side cameras indeed, the Hurricane Rig can be used as a side by side (SBS) rig. But generally when your subject is close (<10m, 30ft) to the camera you need to have the lens centers closer than can be achieved with side by side mounting. It’s common to use effective lens separation (Interaxial) between 60mm and 30mm. There is a general rule of thumb for 3D that states that the closest object in your shot (including the ground) can be no closer to the cameras than 30 times the distance between the lens centers. So if your cameras are 100mm (3.5″) apart then the closest thing you can have in the shot needs to be at least 3m (10ft) away. This rule of thumb comes form stills photography where the print size would be no larger than an A4 page in a magazine. For video applications with screens much larger than that, realistically this rule should be more like 90 times the interaxial, so you more often than not need your lens centers closer than 2″ (50mm).
Q: How easy is the Hurricane Rig to adjust and how quickly can I set it up?
A: From fully broken down for shipping to ready to shoot should take considerably less than an hour. Depending on how much you break the rig down, it can take as little as 15 minutes to set up and align the rig. There are five principle adjustments on the rig. Camera height allows for differing camera/lens heights such as when using an EX1 and EX3 together. Once set this is unlikely to need further adjustment, however when comparing rig specifications do ensure that whatever rig you choose it has the ability to adjust camera height. If you do not have the ability to set this you may end up with Vertical Disparity issues, especially if the rig uses camera tilt to adjust for tilt errors as this is rarely done at the nodal point and will induce height errors. Camera Roll: Again, once set for your camera’s this will only rarely need adjusting. It is done via two thumb screws on the lower camera plate. Mirror Tilt: This can be adjusted to compensate for any camera tilt or lens centering errors and is done with one simple thumb screw at the top of the beam splitter box. As the mirror tilt is correctly centred on the rigs optical axis, mirror tilt will not introduce the vertical disparity errors often introduced through the use of non-nodal camera tilt. Convergence: Allows you to ensure the cameras are parallel for calibration and then can be used to adjust the toe-in and convergence point if you shoot converged. Again this is an easy to adjust thumb screw with a locking ring. Typical adjustment range is 1 degree of toe out to 4 degrees of toe in. Interaxial: This is the one that you will be using a lot to set and re-set the camera separation. This is a small hand wheel with direct calibrated scale. In mirror mode the convergence can be adjusted between zero and 110mm (4′) and in side by side mode you can go from 110mm (depending on camera width) to 400mm (16″).
Q: How easy is the rig to transport?
A: The Hurricane Rig was designed with air travel in mind. I was fed up with paying lots of excess baggage to lug around a bulky beam splitter rig. The Hurricane Rig weighs approx 7kg and packs down into a single small pelican style case (1600 Pelican case). The mirror box folds flat. Typically I can get a pair of XDCAM EX cameras and a rig on most flights without paying excess baggage!
Q: Do the cameras need to by synchronised?
A: Short answer: yes, you will need to have at least one genlocked camera to sync it to the other camera or an external sync source, or use LANC equiped cameras and a 3D Lanc controller. Long answer: If there is not a lot of motion in the scenes you are shooting then you might get away with non sync cameras. Don’t be fooled in to thinking that you can correct for miss sync in post as this can only adjust whole frames and the cameras may be running only half or some other fraction of a frame out of sync. More info on the important subject of camera sync by clicking here. Stop Press! A work-around has been found that enables you to get a pair of Canon DSLR’s into reasonable sync for 3D production.
Q: What cameras can I use?
A: You can use any pair of cameras that will physically fit on the rig. Ideal cameras are Sony EX3’s (or EX3 plus EX1R), Sony F3, Canon XF105, Sony HDC-P1, SI-2K mini, Red Epic, Red Scarlet (if it ever appears), Canon H1’s, JVC 790’s and many many others. You can also use DSLR’s but please see the note above about camera sync. maximum camera/lens weight is approx 8kg total, or with the optional bolster kit approx 7kg per camera (14kg total). The Canon XF305 can also be used but the protruding microphone restricts how wide you can shoot.
Q: What is the Field of View and what lenses can I use?
The rig will accommodate cameras/lenses with a 70 degree horizontal field of view in most cases. For a full frame 35mm sensor camera this equates to about a 17mm lens. You can go fully wide with an EX1 or EX3 (5.8mm, 1/2″ sensor) without any part of the rig or camera appearing in the frame. This is a good figure for a rig of this type. Typically beyond a 80 degree FOV the lens of the opposing camera will come into shot with almost any mirror rig due to the geometry of a 45 degree mirror system. A bigger mirror won’t actually help.
Q: What is the light loss?
A: As the mirror is a true 50/50 mirror then each camera only gets half the light, so the light reaching each camera is reduced by 1 f-stop. It is impossible to design a mirror rig with less than this, the light is after all being divided by two, I would be very suspicious of any rig with anything other than a 1f stop per camera loss.
Q: Can you teach me how to use it?
A: Yes! There have been and will be workshops around the world on an on-going basis as well as additional on-line resources on this site. We have an ever expanding network of trained dealers around the world that should also be able to assist with training and advice.
Q: Is it good enough to make a movie with?
A: Absolutely and in fact it already has! The Hurricane Rig has been used as the primary rig on several features as well as second unit on others. Use the right cameras and there is no reason why the rig can not be used for a block buster movie. A pair of Sony PMW-F3 35mm cameras would be an excellent choice for low budget movie production. Our mirror is very good and it is the mirror that ultimately governs the image quality. The rig has also be used to shoot several 3D cinema commercials.
Q: Can I zoom with it?
A: Yes you can, but you might not want to! First you will need to find a way to synchronise the two zoom lenses. This can be done with most newer 2/3″digital broadcast zooms. Fujinon now have available special matched pairs of lenses for 3D applications. But it is hard to do with smaller compact camcorders as the lenses do not normally zoom in sync (we are working on a solution) and as a zoom lens changes focal length the center point shifts slightly which will miss-align the cameras. Besides which zooming in and out in 3D is not a pleasant effect as the zoom magnification will foreshorten the image while the 3D depth increases. It’s a pretty nasty effect and probably best avoided if you can. Best to shoot one shot, then re-frame and shoot the next which is easy enough to do.
Q: Is the mirror delicate?
A: The mirror is made from optical grade white water clear glass, so drop it and it will break. The mirror coatings on the surface of the glass are to military spec, so gentle cleaning is not an issue provided you follow our cleaning guide included with the rig. In addition the mirror frame assembly will give the mirror some protection during transit and every day use. If treated with respect you should not break it. The mirror is however user replaceable, replacement mirrors are available for $500 USD approx.
Q: Why is the reflected camera mounted below the mirror instead of above as on some other rigs?
A: Several reasons: This rig is optimised for use with lower cost cameras. These will often have CMOS sensors. This orientation of the cameras will minimise any miss match between the scanning of the CMOS sensors. Some “over the top” configurations will exaggerate these errors and make the material un-useable when the rig is panned or if anything moves through the shot due to the skew of the two CMOS cameras going in opposite directions . This layout works very well with Stedicam type devices and tends to work better with smaller and lighter tripods. If you put the reflected camera above the mirror the whole rig becomes very top heavy and will want to tip forwards very easily. It also raises the center of gravity and as a result a larger, more expensive tripod is required. Our rig can be used with most mid range professional video tripods and this helps keep the overall cost of ownership down.
This is a budget rig, how do I monitor my 3D?
I strongly recommend Transvideo’s range of highly portable 3D monitors. These have an excellent range of features and are excellent tools for serious S3D production. However, they are high quality, premium monitors and as a result come at a premium price. You could consider renting one. There are however a number of other options including new lower cost monitors coming to market very soon.
One of the lowest cost monitor solution is to use a Black magic HD-Link 3D (or AJA Hi5) to combine the two HDSDi outputs and give a DVI output (requires a cheap Display Port to DVI adapter). This can then be fed into a Zalman ZM-M215W 21.5″ or ZM-M240W 24″ 3D passive monitor (make sure it’s the newer 1920×1080 model, not the older one). You can then use cheap RealD glasses. The BlackMagic box can output HDMI or DVI so it will also feed almost any professional or consumer 3D monitor. The JVC 46″ 3D monitor is very good and uses passive glasses, but you could also use a consumer 3D TV with passive (LG, Samsung) or active glasses (Sony, Panasonic). The cameras must be genlocked correctly for this and most other 3D monitors to work correctly. One way to monitor on location or with non-sync cameras is to use a Laptop PC with a pair of USB capture devices such as the startech or EasyCap DC30 (typically about $30 US each). On the PC you install stereoscopic multiplexer http://3dtv.at/Index_en.aspx and this will allow you to combine the two feeds and view via anaglyph and many other options. If you use one of the new Acer 3D or Sony 3D laptops you can view the image in 3D using active glasses.
What Upgrades and Options are Planned?
We have a full range of exciting upgrades planned for the Genus Hurricane Rig. One promise is that all rigs will be upgradable, so you can rest assured that even if you buy a rig now our future options will still fit. Our planned upgrades are a special large mirror box for film and movie applications. Full FIZ (focus, Interaxial, Zoom) motorisation options (both low cost minimalist and high end precision). Shoulder mounting kits and even a system to allow motorised correction of zoom offsets. We are also looking at a full de-polariser system and non-polarising mirrors. We welcome suggestions and feedback from our customers.
* Subject to change.