The details shared here apply to the most recent version of Turbo. To keep your theme up to date, check out this helpful document.
While we always recommend uploading same size images (with similar aspect ratios) for your slideshow banners to ensure consistency (see our Image Size Guide here). In some cases, you might want to have a combination of sizes, or use both portrait and landscape images.
In general, the slideshow section's height is determined by the largest image's height! So if you try to upload different sized images, often there would be a large whitespace underneath the smaller images as it's taking the height of the tallest image:
With the 'adaptive height' slideshow setting, this now allows the slideshow height to adjust based on the height of the individual images in each slide! No more whitespace below.
To enable this setting, head into Customize > under 'Sections' > click into your 'Slideshow' > and enable 'Enable adaptive height':