Sooc shots of Osprey. Not sharp, Lots of noise

Started 3 months ago | Discussions thread
FingerPainter Forum Pro • Posts: 10,250
Why you got f/9 and f/8

Elliern wrote:

**One thing though, I always use f4 as you suggested and I just looked to be sure it hadn’t moved and is still on f4. So how is it possible for it to show as f8 and f9???

You seem to have been in S mode with a manually set ISO. In that situation, you do not set the f-number. The camera does. For the metering solution that the camera came up with, it couldn't get the image lightness it wanted at the shutter speed and ISO you set without stopping down to f/9 or f/8.  If you want to control both the shutter speed and the f-number, you need to use M mode. I'd suggest using M with Auto-ISO for shots like these.

Using f/9 with a 1" sensor is like using f/24 on a FF camera - it will result in a LOT of diffraction blur. That's the main reason your first image isn't sharper. The second image, at f/8, has almost as much diffraction blur.

The other problem you mentioned was noise. In general, you get noisy images when they don't capture enough light. By setting the ISO to a value of 400, instead of leaving it at the base ISO of 100, or using Auto-ISO, you told the camera to capture only 1/4 as much light as it could have. The result was an image that was noisier than it needed to be.

If you are going to be using an autoexposure mode (P, A or S), you might as well use Auto-ISO. It won't raise the ISO above base unless it has to. If you had used Auto-ISO with your choice of shutter speed, the camera would have used f/4.5 and ISO 100. This would have resulted in less noise and less diffraction blur.

As an advocate of using Auto-ISO, I'd say this was a classic example of the pitfalls of setting ISO manually. Because of a choice of too high an ISO, you got noise and diffraction that just didn't have to be there.  I guess people who dislike using Auto-ISO might say this is a classic example of choosing the wrong ISO value. Either way, with a small sensor-camera like your RX10IV, you need to very vary careful not to end up with too high an ISO value restricting how much light the camera can capture.

There was another factor contributing to the noisiness of the sky, however. With a bright blue sky, there isn't very much red or green light being captured, even with good exposure settings. On a small sensor like the 1" in your RX10IV, this will still result in a fair amount of noise. Even fairly simple noise reduction tools can address noise in a clear sky, as there isn't any detail to preserve.

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