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Zoom Blur

Posted: April 5th, 2025, 1:41 pm
by Marpel
A couple questions -

1. A little confused as to what ZB actually represents - Does it represent zooming a lens in or out (don't currently have a zoom lens handy to test out a real zoom)?
2. Flowing from first question - I have ZB'd an image which has walls (vert and horiz) and other objects and the zooming effect appears to "pull" and "push" (for lack of a better description) the walls/objects both away from and towards the zoom centre. Is there a way to cause the effect to act more like an explosion so the effect "pushes" everything away from the centre, so there is no zoom "stuff" emanating from the wall/object back towards the centre?
3. I am confused by the Help description, in particular in one sentence "...that simulates zooming the lens while taking a time exposure." Followed in the next sentence by "This effect differs a little from what you get using a zoom lens since....". Isn't "zooming the lens" the same as "using a zoom lens"? Or is it referring to something else?

And, just an FYI, I had set up a zoom with parameters on an image and wished to Reload Last Settings on a second image. Due to circumstance, there was a days gap between the first and second, so I was not completely sure of the Blur Slider setting, although it turned out to be 25%.

However, when I clicked Last Setting, the dialogue only changed the slider number, and the white slider remained at the far left end. Because that number coincidently was 25, I was a bit confused as to whether the Last Settings was recognized or if 25 was the default start point on the slider (had I set it to 39.6 as an example, I would have quickly recognized the difference). My confusion was further compounded by the fact that the + sign in the image remained in image centre and did not move to where I had previously placed it.

As the ZB takes a while on my computer, I immediately cancelled as I did not wish to waste time doing ZB with Default settings. When I did the whole thing again, the number changed as it should, but the slider did not move, and funny enough, the slider jumped to the 25% location immediately after the operation was completed.

Re: Zoom Blur

Posted: April 5th, 2025, 1:59 pm
by jsachs
What it is doing is to blur each pixel with the adjacent pixels, but only radially. You are right that this does not really simulate changing the lens focal length during an exposure which would blur only either inwards or outwards but not both. I could certainly add a setting to provide these other two options.

While PWP is recomputing the transformation, the controls may not be fully updated until the transformation is complete.

Re: Zoom Blur

Posted: April 5th, 2025, 8:12 pm
by Marpel
Thanks for the response.

Re: Zoom Blur

Posted: April 6th, 2025, 5:15 pm
by Marpel
Thought I would mention, I tried the new ZBs and the one I was most interested in, Zoom In, is great.