Trying to decide between DF and D610, IQ differences

Started 4 months ago | Discussions thread
Luke Kaven
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Re: Trying to decide between DF and D610, IQ differences
In reply to Jack Hogan, 4 months ago

Jack Hogan wrote:

Luke Kaven wrote:

Jack Hogan wrote:

Luke Kaven wrote:

On my D800, if I shoot at ISO12800 at 1/80th, there is a bluish-magenta cast over the frame with local hotspots. You can't color balance this out. If I've been using live view, the effects are even more severe.

Everything below that is a matter of degree. At base ISO, it's negligible. I'd say up to ISO 1600 is pretty safe at handheld shutter speeds, and even a bit beyond.

Luke, what happens if you stop at ISO1600 (exposure at 1/80th as you would have it) and compensate for the lower brightness during conversion? Any ISO past 1600 is done digitally in-camera by the D800/D610 anyways, so unless you need a bright image SOC you might as well see if that gets rid of the cast.

Hi Jack,

As you say, since all gain past ISO 1600 is done with digital multiplication, there is no penalty for capping your ISO setting at 1600 and then determining later, perhaps much much later, whether or not you want to apply additional gain. The only penalty would be that your image review would be somewhat difficult to read. And so be it. Sometimes I think the "underexposed" version of the image is pleasing anyway.

Right. Have you tried to see what happens to your color cast if you stop at ISO1600 instead of heading to 12800? I am curious, but in theory nothing since multiplication is not too energy consuming/heat generating when taking average photographs.

If the color cast is due to heat buildup, my guess is that the culprit would be having the sensor on for a long period of time (more than a few tens of seconds) - as opposed to the ISO setting. So filming, prolonged LiveView or astrophotography may suffer, but not typical OVF photography.

I'm saying that ISO 1600 plus 3 stops of digital multiplication in post is exactly the same as setting the camera to ISO 12800 as far as thermal noise is concerned.

Unfortunately, it seems that heat buildup is nearly instantaneous.  I remember I was taking night shots handheld on the Brooklyn promenade one night.  I took around 5 shots in a half hour.  1/80th as I mentioned.  Lots of thermal noise pollution.

Then I tried running live view for one minute, and took another picture.  That was approximately twice as bad.  But after another minute or two, it was back to the previous levels.

I do agree with you in part that the amplification phase per se is not especially to blame.  It isn't purely "amp glow" that we're seeing.  Merely the act of using the sensor is enough.

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