Nice article on why to shoot RAW...

Started Oct 11, 2007 | Discussions thread
Sam Jones Regular Member • Posts: 344
Re: Absolutely Correct

Bill Janes wrote:

RomanJohnston wrote:

ISO 340 isnt optimal...just where you want to stop cranking up the
iso because EV adjustments in RAW match or do better than shooting
the higher ISO.

100 is still optimal.

If you expose at unity gain, rather than a higher ISO, then you can
increase exposure in the raw converter when needed and get the same
results as exposing at higher ISO, but you will have more highlight
headroom as Roman points out.

If you expose at unity gain, rather than a higher ISO, then you can
increase exposure in the raw converter when needed and get the same
results as exposing at higher ISO, but you will have more highlight
headroom as Roman points out.

http://www.clarkvision.com/imagedetail/digital.sensor.performance.summary/index.html

Bill Janes

Bill,

In layman's terms lets say for examples sake that at 200 ISO a full aperture of F1.4 requires a shutter speed of 1/8 to expose an important highlight reading somewhere between 250 - 255.

I wish to increase the shutter speed to 1/30 for less chance of camera shake.

1. Should I increase the ISO two stops to 800 ISO and set the shutter speed to 1/30?

or

2. Should I expose at 200 ISO F1.4 at 1/8 sec, thus underexposing by 2 stops, and increase the exposure in ACR by two stops?

Working out manual exposure techniques and adjusting an incident lightmeter/spot meter to each sensor from GM ColorChecker tets, whether very close to 255 (within 1/10th of a stop for normal), or routinely over at +1/3 - +2/3 and recovering highlight data is not an issue for me but sensor science (unity gians, etc) goes over the top of my head as a photographer.

I have heard arguments for underexposing and making large gamma moves in RAW converters but I see ugly noise in the shadows (ACR V4) although the tonal range is less damaged.

I do understand that as the ISO is boosted the tonal range is squeezed and the highlights are affected - less headroom.

Is it to be method 1 or 2 above?

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