Parallax sections - parameter

Hi!
I've found no detailed documentation how to use the positioning parameters in parallax sections (data-center and data-top-bottom)
My example:

<section id="page-title" class="page-title-parallax page-title-dark page-title-center" style="background: url('images/temp.jpg') no-repeat center center / cover; padding: 140px 0;" data-center="background-position: 0px 50%;" data-top-bottom="background-position:0px 100px;">

            <div class="container clearfix">
                ...
            </div>
        </section><code></code>

Positioning of image before scrolling is working, but while scrolling the parallax motion is way to fast.
Thanks for your answer!
Aixtreme

(of course source code without "``" which was added automatically while using the code tag)

Grmpf...

Thanks for your answer!
Unfortunately this is not working with your approach on my site.
While my first attempt with data-center="background-position: 0px 50%;" data-top-bottom="background-position:0px 100px;"
was moving to fast
(see https://www.aachen-acoustics-colloquium.com/relaunch/program.html)
now with your data-bottom-top=”background-position:0px 0px;” data-top-bottom=”background-position:0px -300px;”
there is no parallax motion while scrolling.
(see https://www.aachen-acoustics-colloquium.com/relaunch/program_test.html)
Any ideas?
Thanks for your answer!
aixtreme