I think I have a solution:
In your personal style sheet page, assign the width & height to match your image dimensions.
Create an additional separate "class" on that top div that appropriates the space with spans...(Shown below)
<div class="span6 columns" class="carousel">
<div id="myCarousel" class="carousel slide">
<div class="carousel-inner">
<div class="item active">
Without touching the bootstrap.css, in your own style sheet, call "carousel"(or whatever label you choose) to match the width and height of your original pix!
.carousel {
width: 320px;
height: 200px;
}
So in my case, I am using small 320x200 images to carousel with. There is probably preset dimensions in the bootstrap.css, but I don't like changing that so I can try to stay current with future releases. Hope this helps~~