Tom Yanowitz
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Everything posted by Tom Yanowitz
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Hi everyone, as I'm involved in low budget filmmaking, I'm interested in knowing what I can do lighting wise, when shooting in houses and just using the regular wall plugs, without the gaffer having to do any setup for bigger lights. It's a topic where I feel quite rusty. In the US, I believe your theoretical limit is 120v*15a = 1800W per circuit. In France, we can in theory go up to 230*16 = 3680W. 1/ At the rental place, is this effectively the thresholds that divide lights that come with regular plugs and lights that don't (32A only) ? 2/ Does that mean that some lights (for example a 2.5k) come with a regular plug here but not in the US ? 3/ What are the brightest lights that you know of that can be plugged into regular home wall sockets ? For some reason I have - for France - the 2.5kW HMI, but I don't know all the lights, and I especially don't know how far LEDs have come in the last five years. Given their efficiency, I suppose a 2K (actual, not "equivalent") LED Fresnel would have an amazing output, if that even exists/could exist. 4/ Do you have a set safety "wiggle room" in mind, for example you would remove 20% of these theoretical max output and end up with 1500W in the US and 3000W in France ? Sorry these questions are a bit all over.. Thanks a lot for reading.
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I'm suprised no one mentioned these lights so far on this forum. For their price they produce a quality soft light ! They exist in 60x60, 90x30, and 30x30cm I recommend ! But not being dedicated film lights they're not easy to put on a stand. Any creative electrician here could help me out on what kind of stand/accessory I could buy to be able to orient them as I wish easily (including "tilting" up and down) ? I have the 60x60cm version that weighs a good 5.3kg (almost 12 pounds). Here are some pictures of what they look like from behind.
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Here's the most simple way to view ISO for most cameras. If you shoot raw or log (or a log'ed RAW..) then you can view the ISO setting as nothing more than tweaking the luminosity of your image when grading. In most log/raw recordings, the ISO setting doesn't really influence what's recorded. What counts is the amount of light, the aperture and the shutter speed. You can try it yourself, pick up a camera, expose it for a given ISO, then don't touch at the aperture/shutter speed and record and different ISOs. Then color correct them all (maybe using exposure compensation LUTs) to the same exposure. It's likely they'll all look the same. The only thing that matters is whether you give the sensor enough light or not. I shoot s-log2 on my a7s 2 and the minimum ISO I can select is 1600, but most of the time I expose it at 200 or 400. Then during editing I have my exposure compensations LUTs. You can have any ISO selected on your Alexa, like 800, and decide you don't need that much highlight protection so you can shoot at EI 50 or 100, juste like in the 1960s. And you thus need much less NDs.
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Thanks for the answers ! Yes of course choice of color, lighting, and everything in front of the camera plays a part. Do you know a place where you can find what film stock were used at this era in this country ? And if film stocks were sometimes improved but kept the same name ?
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Hello, For a project I'd like to reproduce (or get as close as possible, even if you can still obviously tell) the look of black and white of the mid-60s 35mm. I will record color digital, so that film grain could either be the result of a LUT or visual effects. Think "Masculin Feminin", "Persona" (both from 66), so pretty noticeable grain, as much in the highlights as the shadows, plus the particular roll-off in the shadows as well. I'm afraid most film stock LUT offer mostly recent film stocks. Only clip I could find of decent enough quality to observe grain Thanks a lot!
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Just created a Youtube channel on digital cameras
Tom Yanowitz replied to Tom Yanowitz's topic in General Discussion
Thanks Tyler ! Indeed it was supposed to be in book form in the beginning (starting with my end of studies essay) but I thought I might potentially reach people more easily though 10 or so minutes videos. There will be a specific video on ISO of course :) ! I'll try to make more digestible visuals in the future for sure. -
Hello everyone! https://www.youtube.com/channel/UC4HtBBgGiacMtrgqOK1WClQ/videos A bit of shameless self-promotion here but it's closely related to this forum so I guess that's ok. I created a new youtube channel where I will try to study the technical side of cinematography under a 50% engineering 50% cinematography angle. I already uploaded a first batch of videos dealing with Dynamic Range. Any comment, good or bad, advice, outrage... is welcomed ! I love heated debates.
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Sony a7s II video compression
Tom Yanowitz replied to Tom Yanowitz's topic in Camera Assistant / DIT & Gear
Thanks for your answers ! Yes I know their is inter-frame Gop compression so the pixel weight I gave were more useful as relative values to be compared against each other than absolute values. Yes I agree those codec limitations are frustrating. But the a7s II performs surprisingly well in post for an 8bit files camera I found. -
Hi there, I'm asking myself some questions about compression in the sony a7s II's various recording formats and maybe some of you know the answer. I tried to calculate the mean (file) size of a pixel in the different formats to compare the amount of compression: 4k 30p 100Mbps : 3.33 Mb per image = 0.40 bit per pixel (on average, obviously) 24p 100Mbps : 4.17 Mb per image = 0.50 bit per pixel HD 24p 50Mbps : 2.08 Mb per image = 1.00 bit per pixel 30p 50Mbps : 1.67 Mb per image = 0.80 bit per pixel 60p 50Mbps : 0.83 Mb per image = 0.40 bit per pixel 120p 100Mbps : 0.83 Mb per image = 0.40 bit per pixel Is 4K 24p actually 80Mbps to have the same image quality as 4K 30p, or is it true 100Mbps an thus produce a less compressed image ? Same question for 24 and 30p 50Mbps HD. If 24p 50Mbps HD is actually 50Mbps, it means it's the format with the least compression with over 1bit per pixel on average. If the limiting factor of the camera is a data stream of 100Mbps max, why are there no HD 24/30/60p 100Mbps modes for better IQ ? Is it to keep consistency over compression levels across the various framerates even if it means sub optimal IQ ? But then the 4K 24p should be 80Mbps to fit the 30p compression ? 100Mps for all the different res/framerate combinations would allow the 60p to be better quality than the 120p, as it should, and also allow an even lower compression 24p mode (with over 2 bits per pixel) This would come in handy for specific shots where you'd want low compression over high resolution. Or am I just talking nonsense ? Cheers.
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A good related video
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The size of a mirror used for redirecting light
Tom Yanowitz replied to Tom Yanowitz's topic in Lighting for Film & Video
Thanks for your answers ! And also the semi-unrelated discussion that followed, which is interesting as well. -
Hello, I haven't had a chance to use mirrors on sets yet. My question is : if your goal is to reflect a light source onto the subject, to extend the virtual source to subject distance for fall-off reasons, or for any other reasons, how does the area of the mirror influence the lighting ? especially for Fresnels, or any relatively small and harsh sources ? Unrelated PS : David Mullen, please come and show The Love Witch in France, I want to see that film !!
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Yes we had two, a Classic and a Studio. So no internal RAW.
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I agree with you, once again, one most points David, and Anatole. First I'd like to point out I don't advise changing the aperture for every setup like a madman. One of the reasons you keep mentioning though is the need for a constant noise level. The reason I'm not 100% sold on this specific point is : on the one hand, noise level is almost not noticeable when you give a lot of light to the sensor. On the other hand, DPs seem to often get away with far more important changes from shot to shot. Like going from a wide to a closer shot on an actor : softening the light and/or the lens, adding fill etc... And ignoring this, it feels in the end the rating is a matter of taste : I found that the 7 stops of overexposure at 800 was mostly useless to me, I'm fine with 5, and that the shadow stops were not as good as I wanted them (and I also prefer having the least possible noise), while most DPs want to be safe highlight wise and have the supposedly film-like level of noise. Anyway, I don't know why I keep rambling on about this like a grandpa, my studies are over and I probably won't see an Alexa on a set for the next 5 years.
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My choice would depends on what you want to sacrifice. Great sensor but poor video file (hence poor postproduction) : sony a7s II Mediocre sensor but raw video file : blackmagic cameras
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I don't really like to separate the artistic side and the technical side for any job that blends both, like directing and DPing, but I'll do it for the sake of the argument. (And I also don't like saying this guy is better than this one but will do as well) I think all the following statements are true : 1/ Someone extremely knowledgeable on the technical stuff might never reach the level of someone else that is "just good enough" as a technician. 2/ The more someone learn about the technique, the better his work will be, no matter how deep he delves into it. example for 1/ GreatDP admitted he was far from being an expert on digital cameras. Doesn't matter if some averageDP is, he probably wont shoot pictures with the same overall quality as GreatDP , cause other things like composition and lighting are far more important. example for 2/ However, GreatDP suddenly passionate about digital imaging will shoot better pictures than before. If someone decides to and has the ability to master "both", you end up with Stanley Kubrick. This guy has wayyyy more tools at his disposal to tell his story precisely how he wants, than, say an actor recently turned director, who will rely extensively on his collaborators.
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How often do you end up in a situation were 1.2 ND, ~F/8 and 1/50 second still let too much light in though ?
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The more we talk about these "new" notions, the faster they'll enter the realm of basic technical photo/cinematography knowledge I think. That method would be ideal if manufacturers could allow us to display raw data on waveform monitors, but currently we only get access to a heavily modified (for display) data. For example with the Alexa if you record in arriraw, what you see on scopes isn't arriraw but LogC. So a middle gray exposed at ISO 800 with the camera on EI 800 will show up at 39% of the scope, but will be recorded at 15%. So on set monitoring is a bit unreliable in that way.
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So when some random dude on the web talks about ETTR evryone dimisses him as a clownn, but when John Seale does it (or accepts to do it), suddenly it becomes the new hip thing. http://www.avclub.com/article/read-crafting-mad-max-fury-roads-more-2000-visual--220462 Jackson even pioneered a brand new technique of overexposing all the daytime shots so they would look better when converted to night. BRAND NEW right... I'm not even sure what overexposing means with the Alexa. I'm guessing they're reffering to EI 800. EI 800 overexposed 2 stops is just EI 200 with the wrong metadata, it's also the same as EI 1600 at +3 or EI 50 at -2. So they shot their DfN at 200, that's it, which goes well for the high contrast high saturation night look they went with. For shots like this one, 5.5 stops of overexposure (ei 200) was probably enough. If it turned out some elements were going to be clipped, they would have close the aperture (= gone for a higher EI), that's how ETTR works. Maybe they did clip some specular highlights though :
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I came across this article recently.
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Ok but how do we define native ISO then ? Some propositions : - ISO at which the camera gives X stops of overexposure before clipping ? - ISO at which the camera has the same number of stops of over and under exposure ? This second points depends on what we include as dynamic range, which is, for the shadow end, pretty hard to do. You have the choice to end the dynamic range in two ways: above a given SNR level (hard), or below a given number of values per stop (more straightforward). Some examples with the Alexa : - native ISO 1 = I want 7 stops of overexposure = 640/800 - native ISO 2 = I want 5 stops of overexposure = 160 - native ISO 3 = I want as much DR in the highlights and in the usable shadows. 3A : usable shadows stops = stops with 16 values or more. So DR = 12 and the native ISO 3a is 250/320 (+5.5/-5.5) 3B : usable shadows stops = stops with 64 values or more. So DR = 10 and the native ISO 3a is 160 (+5/-5) The highlights stops each have about 500 values in arriraw.
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Wow really ? 65 footage flashed at the airport damn... Still I think that it could have looked great but given Iñárritu's new long and very complex shots style, 65 film would have been slightly too crazy no ?
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gobbledygook = ˈɡɒb(ə)ldɪˌɡuːk,-ˌɡʊk/ nouninformal language that is meaningless or is made unintelligible by excessive use of technical terms. example : 99% of topics dealing with ISO in the digital world are utter gobbledygook. ISO is an index that is supposed to help us link a camera sensitivity and a given exposure. It has no units. It has more to do with the DP's tastes than the camera. It is VERY different from the camera sensitivity itself, which can be quantified with precise units (electrons per lux.s, volts per lux.s...) There isn't any definitive standard for ISO currently. The most popular one being the REI, which is the contrary of a standard really (it allows each manufacturer to determine ISO numbers how the please). Hence there certainly isn't any native ISO for any camera. What do people exactly expect to be carried in the word 'native' anyway. The optimal ISO depends on the scene, it's light level, it's dynamic range, how clean you want your shadows etc More on all of this in my controversial topic How the alexa really works. http://www.cinematography.com/index.php?showtopic=70643
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Nice stuff man. I started to do sort of the same chart but focusing more on actual sensitivity and actual dynamic range rather than what is advertised (but that requires some testing) We could maybe join our work (j'habite à Paris aussi). The F65 is not Bayer but "Q67" (same thing as Bayer but rotated 45° so you get lines of green photosites) The Q67 sensor is 8K, but a 5.7K Bayer equivalent.
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Thanks for your posts David, Actually before my school I would only be able to shoot on DSLRs etc that you can't really grade. So when I entered the school I was telling myself "finally I'm gonna be able to shoot raw etc" But most of the students projects, even the ones with the Alexa, were recorded with the Rec709 LUT/space 'burned-in', so that we couldn't fix stuff in post, some projects wouldn't even have color grading. So I guess it was partly because they want us do to most of the image on set. Then grading is not just correction/ fixing mistakes of course and can be an extension of cinematography (like O'Brother). Damn pretty tough situation. What I hope we get in the future for digital cameras, is having B "specialty" low-light cameras, the same way we use specialty cameras for slow-motion, or "crash cams" etc nowadays Maybe the Canon ME20F-SH.
