I am a prime lens advocate and user. This was almost exclusively the case and one of the reasons I switched to M43 (smaller lenses and cameras allowed the use of multiple, matched cameras and lenses).
There has been a subtle shift in my thinking. This is worrisome, as I stand by what i believe, that prime lenses have a lot of advantages both practically and philosophically.
better habits of visualisation and “in mind framing”.
better understanding of chosen focal lengths and their potential applications.
more involvement with subject and composition.
better compositional skills
increased immediacy (less lag in the compositional process).
lower profile, smaller and less obvious/intimidating.
generally sharper and cheaper than a zoom.
more realistic understanding of the “character” of a lens (often ideally suited to the job the designer intended it to do).
increased awareness and urgency.
Zooms have obvious benefits*, but these are (I feel) often false benefits for street shooting. The added choices in perspective and magnification come at the cost of more choices (composition confusion), a slight disconnect to the subject and a little added lag when zooming to compose. I really believe that a practiced hand, in tune with the focal lengths they use regularly, will get the shot, often more creatively, than the zoom user.
Compositions are very personal things. Making a composition with a fixed perspective allows the mind to concentrate on the frame at hand, moving the available subject matter into a suitably balanced shape. This is especially true of perspective and depth, which changes as much as magnification when the focal length is changed. Zooming promises the potentially perfect composition, which in my case causes “paralysis by analysis” rather than clarity of thought. This has possibly come from my own habits, but it seems inherently natural.
Primes remove a lot of the “flat footed” framing that zooms can make us all guilty of. We have a lot to think about when framing on the fly. Subject placement, timing, exposure, depth of field and focus. Add in zooming and there is tangible added lag time for the process.
The self regulated fix for this is to pre-zoom to a marked focal length (often one end or the other) and leave the lens there, effectively treating it like a clutch of primes. This is what I am considering for my own work. The problem with this, is getting to grips with the various focal lengths (fluid for 12 to 40 or 24-40 equiv as opposed to a fixed 35/90 equiv.). This is a lot of variety in perspective and field of view. Another issue is the temptation of using available focal lengths that do not suit my ideal for street (distortion added by a wider than 35mm equivalent).
The lure stems from a “one camera, one lens” dynamic, but the reality is, I would likely only use one end or the other, so the added weight and reduced speed would likely impede rather than help.
*When shooting measured, time rich landscapes, their features are perfect, but for near instant street images it just adds one more element to be controlled.