I have always enjoyed hearing the various misconceptions concerning the Zen idea of no mind. So many folks in the west and not a few who are spiritual leaders consider no mind to be referring to not using your mind at all, I have even seen it referred to as a person being stupid or a dolt.
Probably the closest we can get to it in English is, no preconceived notion. It can also be referred to as no second or third thoughts concerning a course of action. However, like most things Zen, if it is to be apprehended at all, it is with the spirit or being rather than the critical mind. Again this falls short, so I will leave it at that.
You can see why this would be attractive to the martial arts practitioner. How many of us at a crucial point in time have hesitated while making a decision? This is a dangerous thing to do when a sword is slicing through the air toward you.
It is really easy to overthink some things and the ego can get in the way as well causing us to worry more about how we might be perceived than what is actually going on.
A friend once asked me a question while we were on a rafting trip. He asked if I ever meditated and I replied, of course, I do it a lot. I asked him what he was looking for that he thought he might find in meditation. He told me that he wanted to focus his mind more and be of one mind. He wasn't sure he had ever experienced that. I told him meditation was great for that but I also asked him he by chance had any extraneous thoughts while we were going through the class five rapid just upriver. The thought for a while and said nope I was pretty focused.
I personally find the state of no-mind is harder to achieve when I am pondering life's questions and directions than when engaged in martial arts or in class five rapids. Of course close to 50 years training in the martial arts helps and many years on the oars as well but still, it is harder when one is thinking of something as open-ended as life and one's direction through life.
So again photography helps. We usually have a bit of time to get a shot when shooting some things, others like street photography, weddings, performance, well that takes quick and decisive action. So let's consider shooting a landscape. Normally you have a couple minutes before the light changes too drastically although this is not always the case. So in those two minutes, you can bog yourself down with decisions, composition, settings, the idea of what you are trying to convey and so on. Here is where I say know your technical stuff so well you don't have to think about it then listen to your heart, it will guide you.
I am really fighting the temptation to go into some lengthy explanation here that I am quite sure would not help anyway. So, when something moves you to shoot, look, feel and try and capture that feeling in the viewfinder then shoot. I think you will be happy with your results.
Know enough about the spiritual life not to get into trouble then relax and don't overthink. No Mind.