Which size is it best to shoot at? I just got my HDMI cable (cost only $5 after instant rebate) and played with the camera connected to my TV and the videos showed in crystal clear quality on my HD TV and they took up the full screen estate, while the photos did not because they were shot in 4:3. My videos are set to the lowest res and no I am not gonna set them any higher because I like having lots of disk space available. I wont do anything with the videos but play them back and they play back really clear in HD. Camera can shoot in 4K however.
I’m not sure I totally understand your question. Are you talking about photos?
In general for photos, the ideal shooting aspect ratio is the aspect ratio of the sensor. Other aspect ratios are cutting off part of what the sensor is able to see. Having more image data available in the original file gives you more control over cropping in post. It’s always easy to throw out image data in post, it’s not possible to get it back if the sensor never recorded it.
From your other threads and posts, you don’t seem to be in a place with your photography where you want to do a lot of editing in post. Which is fine. That might come later or it might never be something that interests you. Again, fine.
But even the most basic file viewing software on a Mac (Preview) allows cropping of a JPG and saving the cropped image (ideally using Save As rather than Save so you still have the original to work with if you don’t like your crop).
The Photos app (also free on a Mac) gives you even more editing tools which may be useful to really bring out the best in the images you are creating with your new camera.
The general rule for most photographers is to capture the most data possible at the time you press the shutter button. This gives you the most options to “fix” or adjust an image in post.
You seem to be really excited about using a “real” camera as opposed to most people just using a phone camera (a comment from your zoo thread). I understand that file size and storage are concerns for you.
You will have to decide where your happy medium lies. I only shoot in RAW on a full frame sensor and would never capture a pic with any in-camera cropping. But I don’t care about file sizes and I expect to spend some amount of time in post to get my images to look just how I want them to. While that’s right for me, it may not be right for you. Which is fine.
You should keep in mind that this is a photography sub-forum. Most regulars are passionate about photography and care about image quality. Most regulars are willing to put at least some time/effort into editing potential “keepers” in post. This is going to potentially influence some of the replies you receive to your threads/posts.