In this lesson Lauren Pierce reviews the finger spacing you need to play with great left hand technique on the double bass. She also teaches an exercise to help you solidify the finger spacing so you can consistently play with accurate tuning. The music she references is provided below this video. 

I hope you enjoy the video. It's taken from here 5.5hr video course 'Double Bass Left Hand Technique' which is a step-by-step method covering everything you need to know about the topic.