consistent behavior or treatment
In photography, being consistent means creating images that look similar. Maybe we shot them with the same camera and lens, maybe we made them look that way in post-processing.
Let's talk about consistency, when we should be consistent and when it's ok to switch things.
I am a big believer in telling stories through a collection of images, be it in a zine, book or exhibition. Let's call it a project: a vision we have, a message we want to deliver, something we want to tell.
Generally speaking, I want to make all the images in a project look very similar, to have the same aesthetic. Otherwise, it might confuse the viewers.
Think of a book: all the words, letters and sentences are the same color and size. Only titles are different to make them stand out, to mark an end and a beginning. All the pages follow the same layout as well. It'd be too distracting otherwise.
There are a few things we want to keep constant or very similar: if an image is monochrome or color, the amount of grain, the contrast, the aspect ratio.
We can emphasize the importance of an image making it bigger, spanning through two pages, for example, or even changing the aspect ratio just for that one.
Different projects might require completely different approaches, though. I believe it is ok to not be consistent between projects: one could be in color, shot with a phone; the next one could be in monochrome using a medium format camera.
If we pick up a different book, we don't mind to see another font being used, more or less margins, a different size altogether. As long as it's kept consistent through the whole book.
I try to apply the same principle to my photography: to be consistent in a project, treating all the images the same way, so they form that body of work where none of its components is more or less important but just another piece of the puzzle.
That's what consistency offers: being able to create a cohesive collection of images that tell a story.