forcegasil.blogg.se - Rawdigger image count

#RAWDIGGER IMAGE COUNT SOFTWARE#
#RAWDIGGER IMAGE COUNT ISO#

Determine the slowest acceptable shutter speed.

It’s interesting to think how one might take photos with a true ISO-invariant camera. Part of the reason I asked is because of ISO-invariance. Let me know if I misunderstood or made incorrect assumptions. Of course, if one has an EVF, one could just look at the histogram to avoid losing of highlights. I never really spent much time thinking about what the meter is actually doing.

#RAWDIGGER IMAGE COUNT ISO#

So, if base sensitivity is ISO 100 with a 12-bit sensor, then ISO 200 would support only 9 stops of underexposure, ISO 400 would support 8 and so on. As another corollary, every ISO step reduces the dynamic range in half, which is the equivalent to dropping a bit. This would not be true for a 14-bit sensor, of course, as it could go 12 stops down. If a meter reproduces 18% gray as 18% gray and if my camera uses a 12-bit sensor, then 10 stops below 18% gray will yield 0, which is the end of the line. It looks like one could go another 1/3 stop above this. Raising this by 2 stops gives me about (184, 184, 184). So, in an 8-bit image generated from the unadjusted RAW file of my white surface, I would expect to see an RGB value of around (46, 46, 46). I then read the pixel value of the unadjusted image–what is the pixel’s luminance value? I see some web says saying that meters assume they meter an 18% gray surface and then provide an exposure so that the result is 18% gray. Let’s say I have a white, evenly lit surface, meter it and take a photo based on the reading. It’s interesting to hear that this exposure could be calculated as between 1⅔ and 2 stops above the exposure selected by spot-metering the brightest spot. Given this, the goal might be to ensure that the brightest spot in a scene does not exceed the maximum photon count supported by the sensor at a given ISO. ISO affects this only in the sense that, since the photon count is multiplied, the dynamic range is reduced–the maximum possible photon count is reduced by half for each ISO step up. In a very simplistic sense, sensors are basically photon counters and count up until they can’t count any higher. This is an interesting observation and I am trying to make sense of it.

#RAWDIGGER IMAGE COUNT SOFTWARE#

It is imperative that you do not exceed that over-exposure limit as there is simply no data to recover and no amount of “magic” in any software that can help. RAW files may support up to 10 stops of under-exposure but they will only support between 1⅔ and 2 stops of over-exposure.