In 2011, I worked on developing a shooting methodology to handle Parallel Stereoscopic 3D acquisition for onthe-fly shooting by only adjusting the interaxial, and having convergence track proportionally to the interaxial distance. The technique is based on Le Méthode Dérobé. The Methodology for shooting involves offsetting the infinity background divergence by means of Horizontal Image Translation on an Overscanned sensor. This method allows for reconvergence in post without image magnification and was key to the success of Stormsurfers 3D, utilising the Silicon Imagine 2K camera, Cinedeck, Bartech remote focus and Heden motor.
Originally posted on CML – 28th June 2011 Tips on the Element Technica Dark Country Rig I have been with using the DC rig as one of our many system for “Stormsurfers 3D”, I can advise a few caveats. Please bare in mind that In some cases we have re-engineered the rig to meet our needs.
1. The motor which attaches to the Interaxial teeth is linked directly to the floating plate – so be careful aligning and then engaging the motor – it will shift your alignment. We created a separate mount which sits on the floating plate to eliminate this/
2. The 4-way adjusters – The brass screw push down and the stainless steel pull up. Always have an allen key in your back pocket.
3. Creating a zero point requires a little fiddling – line up the lenses through the mirror and adjust the side screw to create an end point, then adjust. The camera facing down can be locked tight, yet be a few degrees out – make sure to line it up flat.
4. focus – we engineered a device which sits around the SI-2K with the motor at the rear and a shaft which engages our lenses – you will need to do this manually.
5. Blackout, Blackout, Blackout – make sure that sucker is light tight – look through the front – if you can see anything that is not black – cover it.
6. Filtration – we created a drop down mattebox solution with custom drop in filters.
7. As Campbell mentioned – create some flags to surround the front.
8. If you are using the cinedeck, pull it off the physical rig so you can see it all the time.
9. Pulling interaxial for Parallel shooting. I am using a modified variation of the Derobe method, which I don’t think has been in this manner before – shooting parallel with HIT. I align everything to zero – then horizontally translate to a percentage I want as my infinity point positive disparity. Then by dialling in the interaxial you will have your depth budget with your converged element as your “near” element, the further the “nearest” element –he greater the interaxial. I have marked up a bartech follow focus and labelled distances so that I can pull interaxial on the fly. It works really really well. The HIT metadata will transport direct into Neo 3D.
10. Due to the limited IA capabilities (55mm), we have chosen to shoot with an 8mm for the majority of the observational documentary elements – this yields very good roundess from about 25mm onwards.
11. Iris – this is a tricky bit. We use a number of techniques to cope with the situations we are shooting in, creating a similar system to the focus was not cost effective, and required a major redesign – version 2.0 perhaps…. . Exposing with the sun rising, with two surfers who are just wanting to get off the boat ramp and start surfing. Occasionally setting gain to +6db and setting it back to 0db as it gets brighter. Otherwise setting lens stops with more controlled situations, having the flip down matte box allows us to access the iris of the top camera quickly, then tuning the rear camera for matching exposure using the histograms.
12. The less expensive mirror on the DC rig does exhibit some colour and polarisation issues – we have used one of the 1/4 wave filters to assist with polarisation – the rest is dialled out in Neo 3D for editorial.
13. An obvious one – shoot alignment charts and colour charts at the header of the reel – My preference is to have an A1 black and white checkerboard with siemens stars in the centre and corners.
14. Adding filters directly to the lens – with most lenses suitable for this rig, they are 34mm screw in at the front – filters are very difficult to come across (at least in Australia) – Anything wider than a 12mm will exhibit some vignetting – hence why we have chosen front filtering.
15. Make sure your SSD’s are fast enough with the SI-2K – we use the Crucial C300 256GB. SSD’s specifications are not what they say they are – I cannot press upon you enough this issue. Beware of gain – it will significantly increase your data rate. Do NOT use filmscan1 in 3D mode. A great way to test an SSD’s capabilities is to place the camera at 2K with 12db gain in filmscan2.
16. Black balance may appear on your screen every now and again – be mindful and have lens caps standing by. If a camera tells me to do one – I do not argue.
17. We have been using the Cineroid viewfinder and have been pretty unimpressed so far with the results – still researching better alternatives.
18. If using in handheld mode – try to balance the unit so that the weight is just forward of the operators shoulder. We created an extended plate with battery mounts at the rear to power bartechs and balance the rig inwards. We have also created a mount to allow for a Easyrig and be clear of all the necessary bits to take out the slight top heaviness of the rig.
19. If using C-mount lenses, beware of different magnification of each lens, also beware not to overtighten/undertighten which can cause the same issue. We machined some IMS mounts for some non-Linos lenses which 1st AC Rich Kickbush has been able to collimate beautifully.
20. Use a Heden motor for the interaxial, the M-one is a little too torquie. BTW – we are using analogue motors only and have refined a system which works really well.