How to Make a Slideshow on Tumblrby Andy Walton
Tumblr slideshows allow you to display multiple images as a single blog post. Creating slideshows is especially useful if you want to post a group of related pictures -- for example, photos you took at a particular event -- without putting each image into its own individual post. Tumblr automatically creates slideshows when you create an image post that contains more than one image.
Sign in to the Tumblr Dashboard.
Click the “Photo” button to begin creating a new photo post, and then click on the photo upload box to browse for images.
Select the images you want to include in your slideshow, and then click the “Open” button to return to the Dashboard and upload the images to Tumblr. Click the “Post” button to post the images to your blog.
Click on your Tumblr profile pic to open your blog page, and then click on one of the images in the new post to load the slideshow window. You can scroll through your images manually by pressing the arrow keys on your keyboard.
Animated GIFs cannot be over 1MB in size or more than 500 pixels wide. GIF files that don't meet these constraints display as static images. Tumblr supports JPG/JPEG, BMP, GIF and PNG files of less than 10MB in size. Most Tumblr themes support images of 500 by 750 pixels. To avoid automatic scale-down after you upload your photos, keep your images within that limit.