D850 Read Noise Measurements at PhotonsToPhotos

Started Aug 27, 2017 | Discussions thread
Iliah Borg Forum Pro • Posts: 24,418
Re: Bummer. You really could have learned something in this post.

I think it would be more helpful for everyone if Iliah simply stated how to properly expose



Trial is fully functional for 30 days, usually that is enough time to check several cameras.

If i have to guess, D500, by default, has a lot of head room for highlights

3 1/3 stops from midtone to clipping in the green channel; that is the camera exposure meter is calibrated to put the midtone in raw at 10% of sensor saturation, and bump it close to 1 stop to map it to18% for in-camera histogram and out-of-camera JPEGs.

That is not even starting on white balance.

In a way, D500 has two base ISO settings, the other being ISO 400. At both settings the camera essentially "ISO-less". There is practically no benefit (in terms of image quality) for a raw shooter in using other ISO settings, the ISO vs. noise graph stays essentially flat between ISO 100 and ISO 320 and between ISO 400 and ISO 6400.

It makes sense to apply ETTR before setting ISO. First, one wants to maximize the exposure while metering at base ISO (100 or 400), and only after that to dial ISO in (because ISO is not a part of the exposure, and setting it first stands in the way of maximizing exposure).

In terms of acutance / resolution, it is sometimes useful to sacrifice DoF in favor of allowing more light, resolution drops pretty fast with underexposure. At 4 stops of underexposure (or for "correct exposure" at ISO 1600, if you like) the linear resolution at midtone is decreased by ≈20%, at 6 stops (ISO 6400) - by ≈35%; that is an equivalent of having a camera with half the megapixel count, and brings the question - what is more blurry and less pleasing (due to noise and artifacts), an image taken with the aperture opened 2 stops more than DoF suggests, or an image exposed 2 stops less, but taken at the "recommended" aperture.

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