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Michael Rodin

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    Cinealtas & Arri SR line

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  1. The Meteor 5 I see in the 1978 Volosov textbook is a little different with cemented doublet and a planoconvex in front. The 'main lens' is what focuses light on film, the other part is a small Galilean telescope of variable magnification.
  2. Etendue is a pretty fundamental thing, certainly not limited to imaging or focused light. You can think of it as 'spread' or 'divergence' of light. Or you could think of brightness as a 'conversion multiplier' to get luminous flux of a beam with a given etendue. It's ddФ = L*ddG for any point emitting or receiving light. If we integrate it over the directions of rays (to get dФ, full flux from a single point) and then over the surface of light source/receiver, we'll get flux Ф, which's basically power in either watts or lumens (for visible spectrum). Since it's obviously dW/dt, W for energy, i
  3. https://en.wikipedia.org/wiki/Etendue to get one started. As a quick rough guess, to get illuminance E(L) at distance L you'd have to integrate Intensity(r)*cos(angle with the normal)*dx/(r+L)^2 over r, which's a radius of a large light source. Then you can make some series expansions that will show E(L) is close to inverse square law and approaches it at big enough L/r. It's simple like this if every point of the large source emits a wide enough (and uniform over angle) cone of light that its rays reach the observer at any distance. The ideal case is a lambertian source - a fra
  4. Lamp power is P = U*I = U^2/R. Resistance of a wire is R = 4*r*L/(pi*D), where L is length, D is diameter. Resistivity r (in Ohm-meters) depends not only on the alloy, but on the temperature as well, which complicates things a lot.
  5. Добро пожаловать, Дмитрий! I'll name mostly Russian books. Topics 1-4 and 6 are all dealt with in paraxial optics that are covered in every book on lens design and geometrical optics. You'd look in broad all-round textbooks for the basic stuff: Заказнов, Теория оптических систем. Русинов, Техническая оптика Malacara brothers, Handbook of Optical Design Smith, Modern Optical Engineering Mouroulis, Macdonald, Geometrical Optics and Optical Design Topics 11, 12 and 14 are represented in lens design/synthesis books where merits of different lens formulae are
  6. A thin negative per se is nothing new of course, but the latest fad is underexposure plus low contrast, or "low-con low key" (which already sounds absurd). I'd guess it's a byproduct of soft lighting everything - when there's a small tonal scale and spill everywhere, you're tempted not only to remove fill, but also to bring the key down too much when you're shooting night. Thus only the specular highlights remain in "plus" zones over gray. While there is place for murky images (you may want the subject to kind of gradually come out of darkness instead of showing a clear silhouette and fe
  7. 1. Yes, a B&W image is technically a little different. On color film, image is formed by dyes that are released when the developer is oxidized by exposed silver grains. So it is on some more recent B&W stocks like Ilford XP2. But we tend to use older stocks where the image you see is actually made of sharp "cubical" silver grains. While these emulsions are technically inferior, you'd likely prefer their edge effects and grain as it provides a sort of "dithering" to image, fooling the eye into seeing texture and sharp contours that are actually missing. 2. You're either shoo
  8. It's much harder to produce a decent image on a 3-chip 2/3" imager than on the 35 mm format. FFD is huge in proportion to typical focal lengths (48 mm vs a moderately wide lens of 10 mm), and you need a rather radical retrofocus design to project an image that far from the last surface. Correcting distortion is a real challenge with retrofocus formulae, and pretty much every aspect of engineering these lenses is harder compared to symmetrical designs - thermal, tolerances, etc. These designs are particularly sensitive to tilt and decentering of elements, which means more time spent tuning them
  9. In converging rays, a prism will introduce spherical aberration and astigmatism as well.The larger your aperture is, the wider is the cone of rays pointing to the pixel and the steeper is the angle they converge at. Since spherical grows rapidly with aperture (not linearly, but rather a bit faster than (aperture diameter)^3), visually it kind of unexpectedly kicks in after being very mild in the lower range of apertures.
  10. The lamp will last much (couple orders of magnitude) longer if powered on with a dimmer. Quartz lamps, no matter the wattage, practically never die from age - it's inrush current and shock/vibrations that break them. Abruptly turning a larger light off also causes arcing in the switch - hence there are no mechanical switches on the 20K.
  11. DeSisti fresnels and parlights, LTM Cinepars, LTM Prolight fresnels, open faces by Rolf Bloessl made under the brand of Cine-Mobil rental. With Arri you pay premium for 'Arri' letters. There are also riskier variants like "Юпитер МГЛ". In any case, consult with a gaffer before buying.
  12. Speaking about bi-color - does it actually save time? I don't find myself constantly readjusting CT - at most, I'd change gel once after looking in the monitor. Neither do I understand the need for battery power here. LEDs, with few exceptions, don't have the output to be used on EXT, even on a cloudy day or with an overhead silk you need at least a 200W HMI parlight to do something with contrast - and a 200W can be battery powered too. At 100 lm/W it's just as efficient - and much, much more efficient optically. In an interior, you'll have a couple of 16A circuits in newer buildings and 10A i
  13. In grip&electric, the grip part plays a larger role in shaping an image than the electric. Do you have a minimally decent grip package available to you? Before investing in lights, I'd get a couple flags, a cutter, a floppy, a diffusion frame, C-stands and a combo with a small boom. Of course, there's never enough grip hardware, but such a set fits into a car and allows you to shoot interiors with some spill/contrast control. The second thing I'd get is a small to medium sized Chimera with a grid. It doesn't actually do anything special and can be replaced with a frame and flags to co
  14. There's a popular misconception that video (especially if not debayered in camera) somehow stores 'raw info' about the scene and can be color graded to any palette and tonality while a negative image somehow has a color palette 'baked in'. Actually, it's rather the other way around. Film's main properties - sensitivity, contrast, grain structure (grain size statistics & edge effects) - can all be manipulated with exposure, latensification techniques and development. On top of that you still have color correction - printer lights and digital grading. A video camera sensor is stu
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