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Jan Sandvik

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  1. I think it's the small imperfection in the shape of the dish that will make seams and other small imperfections disappear. I also find solar cookers interesting as a starting point, something like this: (looks relatively easy to put on a light stand) https://www.sunshineonmyshoulder.com/sun-chef-review/ Here is a big one, about 6 x 6 feet (wonder if the seams will show up in the light?) https://www.amazon.com/Rectangle-Concentrating-Temperature-Environmental-Protection/dp/B081P35BJR/ref=sr_1_1
  2. The commercial solutions seem to be either expensive/heavy and smaller in size. I have experience in using parabolic silver umbrellas in photography, they produce a beautiful light. But they aren't as effective since their shape isn't close to perfect, and the catchlights and reflections look ugly.
  3. I thought this DIY Perks build was very interesting. It's a parabolic satellite dish covered with a mirror surface. It's used with a COB led to create some parallel rays of light. To my eye it looks very much like sunlight. There are also some interesting theory in the video. https://www.youtube.com/watch?v=6bqBsHSwPgw To skip to the part where you can see how the light looks, skip to 8:50 http://www.youtube.com/watch?v=6bqBsHSwPgw&t=8m50s I thought this was very interesting, used satellite dishes are practically free and the thing could be lit with just any COB led. Does a
  4. Thanks Satsuki and David, really good suggestions. I think I'll test some gel (like 1/4 CTB) and make it dirty (I don't have clear gel!) and see how it looks. How would a glass gobo with really scratched surface look when projected from a Leko?
  5. I was searching for some "emulation" in case I don't have a window at all, and I would not like to use big and heavy real glass windows. Maybe a thin plexiglass with frosting spray could work.
  6. Thanks for the suggestions... I was looking for something more portable and easy to store solution. If I used plexiglass instead of real glass it could work. My initial thoughts was to experiment with some semi-transparent plastics and maybe tear some holes and see how it looks like. Some sheer curtains could also work, but they often look too even or they have some repeating pattern.
  7. How would you emulate the light coming through an old dirty window? Do you have a standard solution? (I'm not talking about the window frame but the texture) Preferably something that would not burn in front of a tungsten light, but a "led version" would be interesting too.
  8. I wish I hadn't thrown my old rear projection television away. It would have been interesting to do some experiments with the fresnel(?) screen material in the front of the television. I'm not sure how it worked, but it did "aim" the projected image forward since it definitely had a limited viewing angle especially height-wise. Has anyone run any tests how those screens work with light?
  9. Thanks, David – your explanation makes sense. I need to experiment with a 82B filter I have buried somewhere, and compensate by opening the aperture a half stop instead. But there are special situations that still baffle me: I'm shooting with a Blackmagic Pocket cinema camera 4K which has a dual native ISO feature. I have a gut feeling shooting 1250 ISO (low end of the high ISO range) with a blue filter could result in cleaner images than shooting at 800 ISO (high end of the low ISO range) without a filter. But this is a special case and would need some testing, it also alters how tonal
  10. I have found that shooting at 3200K and even lower (household bulbs seem to be more like 2700...2900K) create a lot of noise in the blue channel compared to shooting in daylight. Have you done tests where you put a blue filter (like 80C) on the lens and to compensate for the 1 stop loss of light double the ISO? Will this cause just more noise overall? (of course this depends on the camera and ISO + other factors) I really need to test this myself at some point,
  11. Here is a video that might interest you (Grip Tips: Ep 66: Break test "Wall Spreaders"
  12. I don't know if this helps at all, but... Some years ago I attempted to make an incandescent bulb (~2700K) look like sodium lights. I did this just by using a grey card and my eyes, so it was not scientific or accurate. I ended up stacking Lee Bastard amber and Pale Yellow. With a different camera the results may look totally different. Anyhow, here are the results:
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