(Keith and Lethal: thanks for the info on the HDMI and HD-SDI recording options.)
...the biggest limiting factor in terms of image quality in sub-$10k cameras is typically the camera itself not the codec...
Interesting. So what I hear you saying is that, for example, the Panasonic HMC150 or Canon XH A1 would not look significantly better if they were recorded in, say AVC-Intra or ProRes 10-bit. I'm sure you're correct, but I never suspected this to be the case. Could you please expound on this point?
...most of what I've read puts video cameras between 320 and 640. I also don't know if adding gain in a video camera is directly comparable to moving up in ISO...
As said, ISO is a celluloid thing, and digital cameras only really have an equivalent. Not sure how accurately stated they are across the board.
I have no idea what the correlation is between celluloid film and DSLR sensor “ISO”, but I thought they were equivalent enough that one could use these numbers with a light meter and figure out what to set the shutter speed and aperture to. Am I correct here?
I’ve always read that 6 db of gain is one stop. What am I missing?
Lethal, where I’m really confused is when you say video camera sensors are between 320 and 640. For example, I’ve got a HF100, similar in functioning to a HV30. (It’s a mess to try to set exposure manually because I don’t always know if it’s adding gain. But lets say that, like a prosumer camera, I know how much gain is added and can even dial in a specific amount of gain.) If there is no gain added, is it already shooting at least ISO 320? It seems would need to factor this in if I were to make any sense of using a light meter (like dial in ISO 320 even if there were no gain). But I think I might be missing you here.
...as far as low light sensitivity goes, much of that is dependent the size of the imager and DSLRs have massive imagers compared to prosumer video cameras...
But your question of why a typical camcorder exhibits more noise than a typical DSLR is answered simply: it's all down to the size of the sensor.
Is it the size of the sensor or the size of the photosites? It would seem, for example if Panasonic would have just cut off about a third of the 5D Mk. II’s sensor and used it on its GH1, it would have been able to shoot ISO 1600 with minimal grain (albeit with plenty of jello). Would this be reasonable to expect?
It seems like there’s a bit of argument over the exact relationship between photosite size and sensitivity, with most saying that bigger is better and few saying not necessarily. Before I posted again I just read that the 5D Mk. II’s photosites are 6.25 microns in diameter (.00625mm), and it looks like the photosites on a three 1/3” CCD would be no more than 2.5 microns in diameter (4.8mm/1920 = .0025mm). So the photosites on the 5D Mk. II would have about 6.5 times the surface area of those on a standard 3CCD chip. If the relationship between photosite size (area) and sensitivity were linear, that would be about two and a half stops more ISO. Come to think of it,
if a 1/3" sensor had as much grain at ISO 270 as the 5D Mk. II sensor does at ISO 1600, the relationship between photosite size and sensitivity would look relatively linear. But anyway, there's no comparison. Darn.
Many thanks for your time,
Chris