What are preview and blind
Preview and Blind are two different ways to work without actually outputting the values.
Blind
Blind is a simple way to hide the programmer from the output. When you press the Blind key you are hiding the current programmer values from the output. Then you can change the programmer values just like you usually do. You can then store your programmer content or you can press Blind again to output your programmer.
This can be used to store changes to cues in the background or prepare something in your programmer and then reveal it with a single press of a key.
If you have set a Programmer Time (Prog Time), then this will be used when enter and exit the blind.
Preview
The preview function is more advanced. This can be used to simulate cue transitions or to simply have a look at a cue without changing the output. Instead of hiding your current programmer from the output - and then turn off values you might have in the programmer - you have an separate hidden programmer. This can be used to program cues without changing the current output.
You enter the preview function by pressing the Prvw key and than a key associated with the cue list you want to preview. Then your Fixture views gets a red title bar and it shows you the cue content. You can then run cues in the previewer by pressing the small Go+ and then Prvw. This is a very nice way to make changes without disturbing what's going on on the stage.
While you are in preview you can still operate your executors as normally and run cues on the live output.
Follow the links below to learn more details about the Blind and Preview functions.