As requested Max I have posted this question in the Envision forum.
The standard height of the slide images used in the envision demo for the slider is 468px high.
I want the slider in my case to be displaying images that are 410px high.
What do I need to change to achieve this?
And will any changes be wiped out when I do any upgrades or can it be included in a child theme successfully?
Also - when I look at the Slider slides - the thumbnails do not appear but when I hover over them I get to see the images. I do not want to use timthumb.php re sizing as I am not convinced it is not a security risk still.