X-Pro 1: No exposure compensation in Auto-ISO - is this a bug?

Started Feb 5, 2013 | Discussions thread
nixda
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Re: X-Pro 1: No exposure compensation in Auto-ISO - is this a bug?
In reply to wchutt, Feb 6, 2013

wchutt wrote:

It is not a bug or oversight. In manual exposure mode you manually adjust the aperture and/or the shutter speed to change exposure with your fingers. The using the EC dial is redundant and unnecessary.

You are confusing exposure with ISO. Only shutter speed and aperture determine exposure. In digital cameras ISO just changes the exposure index. Changing ISO lets you use higher or lower shutter speed and aperture combinations. But the only the shutter and aperture control how much light reaches the sensor. ISO does not change how many photons are converted to voltage at each sensor site. ISO multiples the actual photon counts either electronically or mathematically so in-camera jpeg rendering is convenient. ISO does not not make the sensor more, or less efficient. It appears to change the sensor efficiency so the photographer enjoys more flexibility.

This is explained here

http://www.luminous-landscape.com/essays/dxomark_sensor_for_benchmarking_cameras2.shtml

but you have to scroll down to the last third if this very long article.

Auto ISO is useful. If you want to keep the shutter speed fixed to freeze motion and also maintain a constant DOF, then Auto ISO is a convenience - you don't need to go into the menus to change the exposure index.

Here is the behavior on the X-E1. I don't have an X-Pro1, so someone who has one needs to check this:

When Auto-ISO is selected in shutter-priority mode, EV Compensation through the EC dial changes aperture; when ISO is maxed out, then ISO changes.

When Auto-ISO is selected in aperture-priority mode, EV Compensation through the EC dial changes ISO, not shutter speed; when ISO is maxed out, then shutter speed changes.

When Auto-ISO is selected in manual mode, EV Compensation through the EC dial changes nothing.

So in fact, Fuji already allows ISO compensation through the EC dial, but only in aperture-priority mode.

This behavior is inconsistent, at best, and not what one would necessarily want. For example, when shooting HDR (in aperture priority), one would need to remember to set the ISO explicitly. Fair enough. It could be that Fuji is so confident in their sensor that they thought it would be acceptable to ramp up ISO before reducing shutter speed. However, in shutter priority, they thought it would be perfectly fine to have the EC dial adjust the aperture.

Go figure.
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