InspektorGadjet
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JodyB Posted at 12-2 05:44
I'm sure it's already been covered somewhere, but I think it'd be a good thing if someone did a write on on this forum as to the use of filters. When to use them, when not to use them and which one to use for what situation. Thats my problem. I don't know anything about photography and I know there is quite a few experts on here that if they shared even just a little bit of their knowledge, the photo newbs like me could benefit very well.
Hey Jody I will try to explain.
Long story short, there is a technique in film industry, or better said, a standard called the "180 degree rule".
This "rule" states that , if you want to get that cinematic look, the shutter speed of the camera has to be 2 times the frame rate of the movie you are shooting.
So if you are shooting 2.7K at 30FPS the ideal shutter speed is 1/60th of a second.
If you here in PAL system in Europe, is 25FPS so the ideal shutter speed 1/50th.
Film industry 24FPS, shutter speed of 1/48.
This creates a motion between frames, like some blurynes when objects move, that has a feel associated with movies.
Now if there is a lot of light, and you are already at 100ISO (you cant go lower) your shutter speed will have to be maybe let say 1/200 or more, so everything will be too crisp. In order to get that 1/200 down closer to the ideal 1/48 or 1/50, let say you have to go down 3 steps, so you will use a ND8 filter, to "turn" the light down.
Another reason why ND filters are used is because, let say you have a very nice 50mm 1.8 aperture lense for your camera, that 1.8 creates nice "bokeh" effect, which is the out of focus background, in films this is a desired effect, you want the subject in focus and the rest out of focus... well if there is too much light, you will have to change either shutter speed (but you go out of the 180 degree rule) or you have to change the aperture, but you want that out of focus elements! so you use ND filters to darken the light that reaches the sensor.
Couple of useful links.
Neutral density filters names and numers explained:
https://shuttermuse.com/neutral-density-filter-numbers-names/
The 180 degree rule explained:
https://www.polarprofilters.com/ ... speed-affects-video
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