Sergey Block Posted May 10, 2015 Share Posted May 10, 2015 Hi! I have to shoot on Sony F5 in 240 fps in 2K. There are two options in 2K: center scan and scan full frame. To avoid cropping I have to shoot in "full frame scan" mode, but it's need a 2K low pass filter but I don't have such filter. Are there any filter on front lens (4x4, 4x5.65?) is used for this purpose? Thanks a lot for your help! Link to comment Share on other sites More sharing options...
Robin R Probyn Posted May 10, 2015 Share Posted May 10, 2015 No front filter for this.. your better off in centre scan.. thats 2K anyway.. centre crop from the 4K sensor.. to avoid any possible aliasing .. at that frame rate the f5/55 will only record in 2K.. Link to comment Share on other sites More sharing options...
Premium Member Mark Kenfield Posted May 10, 2015 Premium Member Share Posted May 10, 2015 Just test it. You may find that aliasing isn't an issue in full-frame 240fps, in which case you're fine to use it. If it is an issue, halve your focal length and shoot with the crop mode instead. Link to comment Share on other sites More sharing options...
Robin R Probyn Posted May 11, 2015 Share Posted May 11, 2015 (edited) Watch out for any light flicker too.. catches a lot of people out.. you,ll have to shoot XAVC with cards fast enough to handle the data rate. You should be able to rent the filter ? its easy to change yourself.. Edited May 11, 2015 by Robin R Probyn Link to comment Share on other sites More sharing options...
Sergey Block Posted May 14, 2015 Author Share Posted May 14, 2015 Thanks! Do you mean flicker shooting with HMIs? Will Flicker-Free mode on a ballast solve this problem? Link to comment Share on other sites More sharing options...
Robin R Probyn Posted May 15, 2015 Share Posted May 15, 2015 (edited) Found this on the inter web.. see below.. also for 240 fps you will need to shoot in RAW with the RAW recorder that fits V mount onto the back of the F5.. max to internal SxS is 180 .. HMI lighting that uses electronic ballasts will not flicker, but they can be prone to another artifact. This would be Arc Wander, as described in the previous passage, the hot spot of the electrical arc that travels in the plasmatic gas within the glass bubble moves back and forth between the two cathodes. The resulting effect appears as shimmer and colour shift. If one big light is used directly pointed at the subject, this effect can be quite obvious. If many lights are mixed together or if the light is punched through diffusion then Arc Wander can often be limited to an unnoticeable level. Additionally, Arc Wander is much more apparent in a dark studio scenario, when used outside to compliment natural daylight these effects can often be negligible. With the 300Hz and 1000Hz High Speed Ballasts it is possible to achieve high quality flicker free images at frame rates of 1000 fps and in many cases beyond even with a single HMI daylight source. This new technology supplies the lamp with a greatly raised square wave current rather than the typical 75Hz. High frequency ballasts are available for all wattages from 125 W – 18,000 W. It is recommended to still test the lamps at the shooting speeds required prior to a job. Edited May 15, 2015 by Robin R Probyn Link to comment Share on other sites More sharing options...
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