Banding on Z9

vtpeters wrote:

JimKasson wrote:

vtpeters wrote:

MCLV wrote:

As I described here https://www.dpreview.com/forums/post/65887363 , using mechanical shutter will blur the banding. For f/2.8 and assuming shutter location 4 mm in front of the sensor plane we get a diameter of light cone of 4 mm / 2.8 = approximately 1.4 mm. Therefore, blurring caused by mechanical shutter would be roughly 1.4 mm / 24 mm = 5.8% of image height and 1.4 mm / 24 mm * 2000 = 117 pixels of the original image. Hence, I simulated how the image would look if a mechanical shutter was used by applying a linear blur of 117 pixels in vertical direction. I then applied layer mask around Yngwie, so he is not completely blurry. You can see results below.

I'm trying to figure out the math and hope you can help me with that.

1. Fictional distance between shutter and image sensor: 4 mm
2. Diameter light cone: The outcome of 1. dividend by the aperture = 4 mm / 2.8 = 1.4 mm (rounded at 1 decimal)
3. The outcome of 2. revideer by the physical hight of the image sensor =
   1.4 mm / 24 mm = 5.8 %
4. The outcome of 3. x the horizontal size of the (RAW) photo =
   5.8% x 8256 = 478 pixels

So I need to apply Motion Blur at 90 degree of 478 pixels on the full resolution RAW file (and mask out everything that does not need to be blurred) to get the desired result.

Did I get the math (and where the numbers come from) right?

MCLV did his calculation for an image the size of the one you posted, which was 2000 pixels high.

You did your calculation for the size of the raw image, but you used the wrong dimension. You should use the height of the image. The shutter travels in the short direction of the frame. In that direction, the Z9 raw image is 5504 pixels. 5.8% of 5504 is 319 pixels.

Jim

You're right. My mistake. Thank you.

4. The outcome of 3. x the vertical size of the (RAW) photo = 5.8% x 5504 = 319 pixels

Yes, you got it right. However, for the purpose of postprocessing, you can select any amount of blur that will provide desired effect, you don't need to limit yourself to any calculated value.