Constraints on thought

I was having a conversation today about constraints. Most of the time we're in a world where we need to deal with them all the time. Constraints can be external, things like deadlines or stuff that's imposed on us that are out of our control. Many times they are internal.Things are done in a certain way because, many times, that's just how they've been done. There might have been a good reason for it at some point, but those reasons may very well not apply anymore. Other times they are bourne out of the styles at the time.Let's take an example: portraits.Everyone knows that to take a pleasing looking portrait you need to pull out a short telephoto, perhaps an 85mm or something nearby.Well, why is that?Because it makes shots that people expect to see in a portrait. It's easy and low-stress. It makes a generally flattering image with facial features flattened a bit. But it's also not creative. Get a good lighting setup and basically anyone can take the same shot.What about other ways of doing the same thing? Same only different that is.For me, I tend to gravitate towards the highly unconventional 35mm portrait because it just feels more intimate. Sure, the background isn't as blurry, and the features of your subject could be stranger (but only when compared to the "normal" portrait). But it's a different look. Hell, I've done portraits at 21mm before too.The subject has to be sharp.Or does it? What if you can pick a slightly different focus point, but keep the subject the same?Or blurs from motion?All of these are ways that we can subconsciously limit our options.Sometimes the box we need to think outside of is really something that we've built ourselves.