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Michael Rodin

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Michael Rodin last won the day on July 11 2018

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  1. If there's a lab not too far away I'd do a strip test and expose/filter based on the measured density curves. Expired fast film isn't as predictable as old slow stock. That said, low-contrast negative like Vision 3 can tolerate virtually any amount of overexposure. You can literally shoot 7 stops over and get an image (although scanning negative this dense is problematic to say the least). I'd expose expired 5219 at EI 100 or denser if I had to shoot without testing.
  2. Rays don't converge to an intermediate image anywhere in the lens, and in any system the aperture stop is a place where rays are not focused. So the front and rear parts of, say, a symmetrical Planar/Double-Gauss lens aren't independent in a sense an objective and an eyepiece of a telescope are. Two halves of different lenses will still focus light at some distance. Even in wide retrofocus lenses components before and after the stop are both low-power positive (converging). You can get a very soft image with severe aberrations if you're lucky; more likely the spherical will be so bad you'll hardly see an image. Actually, some lenses do have independently corrected components that can be used separately to an extent. Some tele zooms consist of a quasisymmetrical "main lens" and a variable afocal converter (a variable-magnification galilean telescope in substance). A lot of wide-angles are basically a quasisymmetrical lens with an afocal converter. But the components aren't separated by the stop - it's always inside the "main lens".
  3. It's an Apollo 6000. I'd inspect the springs that hold the globe - they get cracked sometimes. That ballast was made by IREM of Italy. As far a I remember, there were even two-phase (2L+N+PE) balasts in the wild. Is your one- or two-phase?
  4. What happens to light in dielectric medium like glass is interesting and you don't actually have to delve deep into QED to explain the basic phenomena. There's a Ewald-Oseen extinction theorem in wave optics that explains whats' happening. Briefly put, the light wave doesn't slow down coming from air into the glass. It stubbornly continues to propagate at the same speed for a while. Doing so, it forces the medium's atoms' electrons to oscillate at the same frequency (it's more complicated really, but a crude approximation works at our visible wavelengths) and generate "secondary" waves (and then "tertiary" and so forth since one dipole excites the other) propagating backwards - thus we have a reflected wave - and forwards. Waves from each atom add up with phase shifts - because they were emitted from different points in glass. There in the sum we have a wave just like the incident one but with the opposite sign, so the incident wave is canceled out. The rest, when summed, looks like a wave propagating slower by a factor of refractive index. And you can view wave optics as "statistics of many photons": while in quantum we're talking about the probability of finding a single photon somewhere, in wave optics we're dealing with an EM wave formed by myriads of photons carrying an energy proportional to their number. Don't take is as legitimate definition though as it's very, very inaccurate. Many concepts (diffraction et cetera) are similar, but they're applied to different objects in QED and classical ED. Feynman's books are brilliant by the way, all of them. And used to be very popular on the other side of the curtain too.
  5. Old Arri Apollo fresnels have actually got better photometrics than newer Compact and D-series thanks to bigger lenses. Color depends solely on the globe, and these lights use the ubiquitous double-ended HMI. Beware of old Arrisuns - the 575 with a PAR36 and the 1200 with a PAR64 lamp. Both globes are extremely rare and a conversion to MSR is usually not worth it.
  6. No - it's the other way around. Rays from a point in object space fill the entrance pupil. Then rays going out of exit pupil converge (not perfectly because of aberrations) on the image plane (again, not exactly a plane because of astigmatism/field curvature). In measuring - none. Theoretically iris can be placed anywhere - but depending on the opening size it'll be either pretty useless (it'll only contribute to vignetting) or, if closed down enough, become the new aperture stop. Depth of field is proportional to 1 / (entrance pupil size). Depth of focus is proportional to working f/number, which depends on pupil magnification (but pupil magnification is a big deal only at close distances).
  7. Only with external recording through SDI. 900R is basically a 900/3 in a smaller DVW970 casing with a built in serializer for SDI output.
  8. Properly stored F64D is fine and holds up well against newer stocks. It has noticeably less latitude than Kodak '03 as it's slightly more contrasty and doesn't go up to very high (say, 1,5-2-2,4 RGB, which is hard for telecine and non-HDR scans anyway) densities like '03. It's grainier too. But one can argue the warm hues are more lifelike compared to Kodak ochre/carmine/cadmium palette. If you come across F64D, do a sensitometery test. If it's still got some 20...30 ASA and tolerable fog, color should be OK.
  9. LAD is basically a quick one-measurement check for under-/overdevelopment. Originally intended for color neg. As far as I remember, Kodak recommended slightly different gray patch densities for various stocks, all of them around 0.8-1.2-1.6 RGB Status M. For B&W, 0.7 over base and fog sounds like a safe grey density. Optimum exposure depends on the post process (and, to some extent, the stock) though. In the photochemical world, a "correctly" exposed negative would print at midrange printer lights. DI is much more complicated and you have to test to figure out the densities that yield the best scan.
  10. Are we talking about debveloping Kodak Vision film cut into 36-exposure rolls for shooting stills or processing film footage at home? The latter just isn't possible without a machine.
  11. I had a Blackmagic CD with older (around 2005 I suppose) drivers and codecs. I recall they worked in Adobe software and VLC. Could upload it here in a couple weeks.
  12. How much stops there are between 0 and 100% is limited your camera's signal to noise ratio. Say, an F900 had, as far as I remember, 54 dB, which means you won't ever distinguish more than 9 stops in the 0 to 95 (or wherever the knee circuit kicks in) IRE range. 6dB equals a stop. Then you add 3 stops (=800%) of range cramped in the highlight (say, 95...105) region nonlinearily - either using knee or with some gamma that has a shoulder (like a film H&D curve). In the latter case it's a bit more complicated since the whole "percents" terminology comes from the world of broadcast-legal video that doesn't necessarilly get color graded.
  13. It's a static detail shot, isn't it? Does anything moving obscure the image in the viewfinder? You could shoot the image in the telescope separately with the exact focal length needed to get the right image scale far enough from the eyepiece, and composite it into the shot. As to focusing, the image of the moon will come out of the telescope in practically parallel rays, which means focusing the taking lens around infinity. And the focusing distance for a (split) diopter will be 1/D if we need parallel rays after it. A short-focus single-element diopter might unacceptably degrade edge definition and introduce CA though.
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