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Guillaume Cottin

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Guillaume Cottin last won the day on July 22 2013

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About Guillaume Cottin

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  1. OK, I was really expecting someone to bring up that sort of thing when I added the Alexa chart. I was tempted to write " I am not trying to compare Alexa vs Blackmagic blablabla", but I thought it was so obvious that it would be an insult to the reader's intelligence, so I wrote instead " Adding some info" and "to have a reference point…" which, I thought, already conveyed the idea that I am not directly comparing the two. But it wasn't obvious enough so let me make it very clear. The subject is how to manage the limited highlight latitude of the BMPCC. The Alexa is the gold standard in highlight latitude. That's why taking that camera as a reference makes sense, but of course whatever tweaking or workflow we are able to invent with the Blackmagic won't match it anyway. Also, the Alexa handles the ISO changes quite similarly to the BMPCC yet with better allocation yet only 5 or 6 stops of overexposure latitude at some settings. That is why it is interesting to see both charts. As for iPhones: isn't there a Godwin law for cinematography that says "As an online discussion on cameras grows longer, the probability of a comparison involving iPhones approaches 1"?
  2. Adding some info. To have a reference, here is the same diagram for an Alexa. (source: Arri). The Alexa has 1.5 stops more DR than the BMPCC4K and its range is better balanced. I would be interested in seeing an over/under key light test at 1000 ISO and exposed for 2000 EI (either with a light meter or by using a custom viewing LUT). If the noise is OK and the image doesn't fall apart, then on paper it should give a nice balance to the BMPCC4K, at +6.3 stops over and -6.8 under.
  3. Hello everyone. Reading the manual of the Blackmagic Pocket Cinema Camera 4K (what a long name…) I stumbled upon this very interesting graphic: As we can see, the curve resets at 1250 ISO to adapt to the new sensor amplification. We can also see that the dynamic range is inferior at the 3200 ISO setting and beyond which is not surprising. What I want to talk about here is the significant unbalance between highlight and shadow latitude especially at lower sensitivities. Shooting at 100 ISO for example, feels like a terrible idea with only 2 stops of DR in the highlights, and a ridiculous 11.1 stops under middle grey. I haven't seen or read anyone talk about it online yet. Maybe people just always ETTR and may therefore never notice this as they never refer use middle grey as a reference. Rating the camera at 1000+ ISO (400 ISO native), gives the more balanced DR at the expense of noise. I have noticed some harsh video-like looking clipping in the otherwise great looking demo footage of the camera. Rebalancing the dynamic range by rating it at a higher ISO might help with those highlights. But then Blackmagic specifically advises not to shoot at 1000 ISO and instead switch to 1250 ISO "for cleaner results". So far this is all on paper because I don't have the camera and the footage Blackmagic provides is not sufficient to completely evaluate this topic. So I am wondering if any of the early birds and owners out there already tried "pushing" the sensor, and if the tradeoff of noise vs highlight DR is acceptable when doing so.
  4. I am surprised that no one mentioned yet the quite popular Astera AX-1 pixel tubes. They're essentially RGB LED tubes. They are rentable and it seems like they can be a great tool for this job.
  5. That's probably because many people, including me, will use the word "translite" as a generic term to describe a backdrop. I've never heard "digital vinyl", I'd call the type I was describing a "day to night translite".
  6. Hi Translite backdrops can be lit from both the front and the back. Light it from the front and you get your daylight scene. Light it from the back and the light passes through all the little windows in the buildings, which are actually semi-transparent, and so this reads as if the windows were lit in the night. Combine both for dusk/morning/etc... As for the choice of sources, it can be anything. Traditionally open face fixtures and molebeams. Kinoflos or space lights.
  7. Skypanel or good olde Kinoflos since you say you are on a budget. Also they are lighter than a Skypanel.
  8. Thanks Chris. Same for the XT Plus or just the SXT Plus? I am wondering in what cases you'd want to use the UMC-4.
  9. A little treat for the francophones in this forum ;-) http://www.youtube.com/watch?v=rrbXkUvOTVg
  10. Hi Connor, check out Secced as well
  11. Hi there, Do you know if the Arri/cForce motors are directly pluggable into an Alexa (S)XT Plus? Does it take a special adapter cable? Thanks
  12. Does the SmallHD 503 have OLED panel?
  13. How funny is that, I was gaffing yesterday and we created a very similar look. We taped RGB LED strips to the low ceiling, they gave us the exposure base as well as a subdued key. Then some strobes and source fours (you can also use par cans) and a bit of haze. Arri L7-C, sky panels and others are more expensive but great. I'd go rent theater lighting for a fraction of the price as you don't need color accuracy. Mirror ball works well with a source 4 or a dedolight These are the basic ingredients, but how you arrange them is really up to your artistic taste
  14. What about HDR monitors and projection? It opens up some creative possibilities in a theater, may change the way you expose
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