How to choose an arbitrary fps - frames per second

Question

I selected the Custom editing mode and still I can only choose some presets. I can't write 20 FPS for example. But I can choose 15 FPS.
In older versions of Premiere you could choose any fps.
Is there a way to use 20 fps in premiere ?
And to not make a new topic, is the empty spaces on the left of the tracks used for something ? I mean sometimes some kind of buttons or indicators appear there ? Because otherwise why is that space empty for no reason ? Seems like a waste
http://help.adobe.com/en_US/premierepro/cs/using/images/es_08.png

Answer 1

The "empty" spaces serve a purpose once you load a clip into the Source Monitor. They allow you to route the incoming video and audio to one or more destination/target video and audio tracks.
There is no direct way to create a sequence with the frame rate you want. I don't quite know why Premiere is limited in this regard, to the few frame rates that are there, but it is capable of creating a sequence with non-standard frame rates.
If you have a clip with a 20fps frame rate, and with all the other parameters you need, e.g. frame size, simply drag the clip to the New Item button at the bottom of the Project Panel. This will create a sequence that matches your clip, including the frame rate.
If you don't have a clip at 20fps, import another clip that has all the parameters you need, e.g. frame size, the right-click it and select Modify > Interpret Footage. Set the frame rate to whatever you need--in this case, 20fps--and hit OK. Now, follow the steps above to create a new sequence. Unfortunately, there is no way to save this as a sequence preset, so you might just want to create a project with a single sequence at this frame rate, which you can then import into your working project whenever you need it.
Here's proof this can be done:
Note that the time display will always be "Frames" since this is not a standard frame rate.