Can't zoom slider
On mobile, tablet and other touch devices the drag option makes the touching action to be different on a slider, to manage the slide switching rather than allowing zooming on it. You should turn this option off, if you would prefer zooming on a slider.
Problem with zooming
A slider's responsive behavior is different from the responsive behavior of a simple image, so when you are zooming them, you cannot have the same result. A slider is responsive, an image isn't. Responsive means, that your website has 100% width of the browser and all your contents will adjust to this width.
No matter how wide the screen is, the slider will never have a bigger than 100% width.
When you go to an image's url and just start zooming it, the image goes out of screen, so it will have more than 100% width.
A scrollbar appears, as the content is not adjusted to the new screen's width.
Options you can adjust
On the Size tab you can find a Limit slide width option. Leave it being turned on, as this limit's your slider to use its Slider size - height as the maximum height. That way as you zoom out to make your contents smaller, the slider will go smaller too.
On the Size tab at the Layout for the Fullwidth and Boxed layouts you can find a Min height setting. You should use it, to not let your slider just go smaller with its original ratio. This way as you zoom in your contents to become bigger, the slider will become bigger too.
The boxed layout gives you an option to make your slider non-responsive. The Upscale makes your slider to go bigger from the given Slider size value, and the Downscale option will let your slider go smaller.
We really don't suggest turning off the Downscale value, as on mobile phones you will need the slider to go smaller, to have a responsive slider.