ISOless sensors, read noise and photography - many questions!

Started 11 months ago | Discussions thread
boardsy
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Thanks Russell - my non-scientific example...
In reply to RussellInCincinnati, 11 months ago

RussellInCincinnati wrote:

OK Alan, have put the time in studying the sensorgen site. IF you don't get color casts/banding during your raw post-processing brightening, it appears that there is no point in ever manually setting a Nex C3 to above ISO 800. Because if you do, you are just amplifying "the noise" as much as the brightness and not really getting anything that you couldn't get in post-processing with a lot more finesse and options. Will be checking this out, the practicality of staying at ISO 800, at least with Lightroom 4.4 for Windows if not RawTherapee and LightZone (i.e. latest dcRaw).

Said another way, you might as well brighten a C3 raw digitally, at your leisure if there's not enough light for ISO 800. Just let the raw file "look superficially dark" and figure you'll brighten it in post-processing.

Of course one downside of not setting ISOs above 800, just underexposing, is that you don't get a nice review of the image in-camera, it will always look grim in the playback menu.

With the Nex 7, a quite different sensor in so many ways, there is no point in setting ISOs above 100, if once again your post-processing does not introduce banding or color casts. At least in the narrow sense of noise in a low-light image, you might as well take super dark ISO 100 photos on your Nex 7 and brighten'em in post processing.

Thanks Russell (didn't know you were still lurking around these forums by the way, been a while since you were in the NEX forum?!), good detective work!

Here's a random example of a shot I under-exposed at base ISO200, around 1/30 hand-held, f2 on the FD 35/2 + Lens Turbo focal reducer, just to preserve highlights and see how it turned out after RAW pp in Adobe Camera Raw. The result is pretty good I think, and brighter than the scene was; sorry I didn't take a high ISO shot for comparison, or note how under-exposed I shot it!

It seems you could use high ISO purely to focus and compose (like an open aperture!) and then bring it back down to take the shot!

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Regards,
Alan
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