I shoot with Canon 5D Mk 2 & 7D. I have been told by 'experts' that we keep the ISO speed to the multiple of 160 e.g. 160/320/640/1280.
So, my question is, when shooting interviews outdoors in fluctuating lighting condition, is there going to be a noticeable degradation in image quality if one choses to vary the ISO to get the correct exposure instead of altering the aperture? The advantage would be that it won't change the DOF if we vary the ISO. BTW, I am in the PAL region and I always keep the shutter speed to 1/50th Sec.
When I shot with a 5d Mk 2, shooting with the ISO in multiples of 160 was key. Especially when filming indoor interviews. When I was outside (during the day), I didn't find it made a lot of difference.
The reason being is that when you shoot in 160 steps, you get the cleanest black you're going to get without a lot of noise. But when I was outside during the day, blacks weren't as important as when I was shooting an indoor interview, so I never HAD to follow the 160 rule because I didn't notice a lot of noise when it was bright out.
That said, I still stepped up the ISO by 160 and just used a VariND filter as I wanted to be sure.
I wasn't aware of the 160 steps. That's good to know. Also, on the 7D, stay below 1600. The 5D, you can push it up to 2000. The MkIII is really amazing. You can push it up to 7000 will just a little bit of noise.
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