slide width, height

This isn’t how Meteor Slides works. The slideshows are fluid and will scale down to fit smaller screens, but they need to have a max height and width to work properly.

but if i leave the width and height blank, shouldn’t the slider scare 100% left and right. what its doing currently is scaling the width of the image, so if my image is shorter than the screen width you have a empty space on the right

No, that’s not how the jQuery Cycle script that powers the slideshows works. It’s not just automatically 100%, it needs exactly pixel value dimensions, which is why those settings have default values. And for the responsive scaling, it scales the slideshow based on the image size.

Really to get the best quality you want to size your slide images to the max dimensions you want, set the slideshow dimensions to that size, and make sure that everything matches exactly. If you blow up the slide images beyond their standard size, they are going to get blurry and just not look good.

There are other slideshows that are made specifically for 100% width and height, like fullscreen or background slideshows, but these generally work best with high rez abstract photos that will scale well even when blown up.