Hosting photos on Amazon S3 is very inexpensive and delivers the photos quickly. (This option not available with Sytist Hosted, only when hosting Sytist yourself.)
How to set it up
Create an Amazon S3 account
First you need an Amazon S3 account. You can create one here: http://aws.amazon.com/s3/
Once you have created an account and logged in, in the AWS section go to S3 under "Storage & Content Delivery ".
Get your security credentials
You will need to enter in this information in your Sytist admin in Settings -> Photo Settings. Do this by clicking on your name in the upper right corner of the AWS console. Click on Access Keys and get your Access Key & Secrete Key. After you create an access key, download the file and save it to your computer. Open it in a text editor like note pad.
You will see 2 lines like this. You will use the content after the = sign
Create a bucket
A "bucket" is basically a folder in your Amazon S3 account. This is where the folders of photos will be stored and will be part of the URL (like s3.amazonaws.com/mybucketname/.....) .
When creating a bucket give it an unique name. Something like yourwebsitename. Use only letters, numbers and dashes and no spaces. Select a region closest to you and click create.
When selecting a region, you will need to refer to this page to get the "endpoint". Both the bucket name and endpoint will need to be added to your settings.
In Sytist, go to Settings -> Photo Settings
Under Amazon S3, enter in your access key, secrete key, bucket name and end point.
When entering your endpoint, do not add the http at the begining or a trailing slash.
Check the Enable Amazon S3 box and update settings.
Be sure to test by uploading just a few photos before uploading or moving a lot of photos.
Moving Photos to Amazon S3
There are 2 ways to move photos to Amazon S3.
1) In the upload photos dialog window, there is a option to move the photos to Amazon S3 after they upload. This will slow down the upload process slightly because once a photo is process (watermarked, resized, etc...) it then moves the photo over to S3 then deletes the created photo files from your server.
2) When viewing photos in the Photos tab of a page in the admin, there is a Move to Amazon S3 button. That will open a window where you can move existing photos to S3. This will move the existing photos to S3 and delete those files from your server.
There is also an option to move photos to S3 in the tray when selecting photos with the check-boxes.