For the majority of the time I have my trusty 24mm to 70mm Nikkor lens attached to my D3, great for for every occasion but rather too weighty for a day out with Mrs B, especially if shops are going to be involved.
This weekend we had an overnight stay in Bournemouth booked, the weather looked promising and I had seen that there has a huge deckchair on the beach that would have looked good in my photography portfolio.
Rather than packing the rather heavy zoom lens I attached my very under used 50mm prime lens, reducing the weight of the camera for the planned shopping element of our short break.
The downside of this lens is that to get closer or further away from your subject is that you need to move your feet but if that was good enough for Robert Capa it's good enough for me.
Using a 50mm lens on a full frame camera gives a very similar perspective to that of the human eye with little distortion or magnification to the final photograph.