Is ISO 400 stretched in PP the same or better DR than ISO6400 not stretched?

Started Aug 10, 2013 | Discussions thread
Per Baekgaard Senior Member • Posts: 1,269
Re: Is ISO 400 stretched in PP the same or better DR than ISO6400 not stretched?

Steve Bingham wrote:

DR is greater the lower the ISO. See the DXOmark DR charts. As ISO increases, DR decreases. Post has nothing to do with it. Hope this helps.


You're obviously fully correct -- but the particular application here the OP most likely has in mind is astro photography, where you need as much sensitivity "as possible" without compromising "too much" on DR.

If you stack shots of ISO400, you will have more DR than for stacked shots at ISO1600, but it depends on the particular scene whether you need it (i.e. which are the brightest stars or parts of the foreground you also want to include). At the same time you will however loose some sensitivity in the darkest parts.

At around ISO1200-1600 you have max analog gain applied and will get as much sensitivity for this type of application as the D800 can offer -- at the expense of a reduced DR.

Above ISO1600 you will not gain more effective sensitivity, but your DR will just decrease.

With a stable tracking, ISO1600 thus becomes the best compromise, and if your shot really "calls for" an ISO6400 exposure, you'd be better off (more DR and higher sensitiity) shooting it at ISO1600 and pushing +2 EV in post.

 Per Baekgaard's gear list:Per Baekgaard's gear list
Nikon D800 Nikon D500 Nikon AF-S Nikkor 70-200mm f/2.8G ED VR Nikon AF-S Nikkor 14-24mm f/2.8G ED Nikon AF-S Nikkor 24-70mm f/2.8G ED +17 more
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