vaga Posted August 15, 2015 Share Posted August 15, 2015 Plaiades Full Show MusicHall NX1: http://youtu.be/_buW5dRZv6cWithin the first few minutes of this video you can see examples of the color clipping phenomenon described in another thread regarding the a7s. What is happening and why exactly does it happen? How can you mitigate this blue clipping effect if you're shooting a concert or live event with similar lighting? Quote Link to comment Share on other sites More sharing options...
sunyata Posted August 15, 2015 Share Posted August 15, 2015 Yea, I tried to help Kristopher with this issue, but the problem was basically unrecoverable. I did make him a LUT though, which just turned the blue spot down to look less saturated while trying not to affect skin tones. Others have suggested avoiding the problem by shooting white balance higher than 5000k and turning PP off. Assuming you were also using SGamut, my best guess is that your problem lies there, specifically it being too wide in the blue corner when scaling into sRGB, and with a lot of blue LED light in your signal -- see image below -- If you look at the problem with a scope, it's not actually clipping blue, it's red and green that are dropping to zero past a certain threshold; blue still has data. That makes sense if you consider how wide SGamut is in B. I also suspect it's the reason people are having other color problems shooting log with the A7s. Another more analog solution could be to use a blue blocker (orange) filter to avoid triggering or overrunning the threshold and then color correcting for the orange in post. Nick Hughes and TheRenaissanceMan 2 Quote Link to comment Share on other sites More sharing options...
Policar Posted August 15, 2015 Share Posted August 15, 2015 Additive imagers (slide film, digital) increase saturation as brightness approaches 100%.Negative imagers (color negative film) decrease saturation as brightness approaches 100%.The Alexa clamps saturation at its highest at 30IRE then gradually decreases it as it approaches blowing out. There's a custom SLOG3 for the F5 that sort of does this, Canon Log and WideDR sort of do this, and Red's new color sort of does this, too. Arri still does it best.I'm not smart enough to figure out the correlation between those gamuts and saturation clamping, but the a7s blows out to ugly colors unless it's white balanced to that one particular color. Sorry.This is why I've always liked Canon's cameras and the Alexa. Great color. TheRenaissanceMan 1 Quote Link to comment Share on other sites More sharing options...
vaga Posted August 17, 2015 Author Share Posted August 17, 2015 Lol. Nice discussion. Very informative. I like how we automatically started talking about Sony stuff when the original video posted was from the Samsung NX1 I've always wondered how color spectrums that are wider than the visible spectrum display colors! I know human eyes can sometimes ssee supersaturated colors, but that's because of nerve fatigue basically. Quote Link to comment Share on other sites More sharing options...
sunyata Posted August 18, 2015 Share Posted August 18, 2015 ha.. you referenced the a7s video and I figured you were dealing with the same camera. What is the gamut and mode you are shooting in? Quote Link to comment Share on other sites More sharing options...
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