When it comes to frames and lenses a lot of things are needed to be considered terms of their relationship and the most popular one is the crop factor. So what is this cop factor and how does it affect the relationship/ results of camera lenses.
This is something that you can see. Do you notice that when you are shooting with full frame versus smaller size sensors using the same lense that you will get different results when it comes to focal length? (distance from the subject). This is not because of anything other than the crop factor.
The ideal: The ideal one is the full frame 36x24mm sensor, let’s consider this as a standard, this is because the crop factor doesn’t sit in unless you go for smaller size sensors like semi-professional cameras and micro 4/3s. So it’s like this; if you have an APS-C sensor for example, crop it by 1.6x. So whatever the lense you are buying you are going to multiply the lens focal length times 1.6 which is going to give you the exact focal length that you will get for APS-C sensors.
So if you put it like this: if you’re using a full frame and you have a prime lens (50mm), when you take pictures you will get the same 50mm result. But if you’re using semis the 50mm will become 80mm, if you want that effect where you need to be nearer, you either buy a smaller lens or move closer to the subject.
Why it matters: When people say that this is just a minor adjustment it’s not because distance is everything. It’s very important and the sooner that you will know this the sooner that you will be able to adjust accordingly and make better decisions and better shots. Aside from this is the technical specs of your camera versus the technical specs of your lens. Like how many FPS, ISO, megapixels and many more. All of these thing you will need to consider (and people tell us photography is easy?)
The fact is that you don’t even have to memorize all of this, what you need to do is understand it. Because by understanding you will be able to think about what can work and what can make better results. Like, what is the best lense in low light for example? The answer is not necessarily buying a very expensive lense, sometimes all you need is the nifty fifty(50mm wide aperture lense) very cheap and very efficient.