When we walk into a shop (or virtually, into an online shop) to buy a camera, you are often presented with the options of "Body only" or "Kit bundle". Next, you will go to Google to search for opinion. Some people would say to get the body only and get a PRO level lens (A fast prime or a fixed large aperture telephoto lens) while others suggest to start off with kit lens to "test the water". After hours of researching, it turns out that there is no conclusive information.
So, the question is, what is the difference between kit lens and a PRO lens, if any?
Short answer: Oh yes! Of course there is a difference (maybe more than "one" in fact).
And the first and most obvious difference is of course: the price!
Let's look at the Nikon DX line as an example. (And no, we are not going to run image quality test, as there are millions of them available on the internet already)
One of the most commonly seen kit lens is the 18-55mm f3.5-5.6, which gives you a Field of View of 24-70 approximately on a 35mm format.
It costs around $120 AUD if purchased seperately.
This is certainly a good focal length range for daily use and truth to be told that if you are a beginner, you probably have no idea about what all those number means apart from your sales rep or your photography friend tells you that it is a 3X zoom lens - cool! No worries!
Now, for the PRO "alternative" (a very long shot), it is the 17-55mm f2.8 DX and it costs.....around $1700 AUD.
YES - you have not misread it nor have I mistyped it, it is indeed 10+ times more expensive: thanks to the fixed aperture and more superior glass quality and overall build.
One may argue saying the lens body build doesn't matter much because it is not used in a fight as a weapon, (oh and I don't really buy the "weather seal" gimmic unless you shoot a lot in rain or in windy place with sandy terrain) the special coating and glass quality can largely improve the image sharpness and reduce flare etc.
The fixed aperture can come in handy too because it can stay as f2.8 no matter which focal length you are using, while the kit variant will have the aperture closing down as you zoom in and hence, lose in light captured and slower shutter speed or higher ISO is needed for compensation.
A PRO level lens may also have a better/quicker AF system that helps you to not missing any (or as many) shots.
But let's go back to the point - it costs 10+ times more!
Here is the thing: Do not get carried away by the marketing.
The kit lens may be inferior to the PRO lens, this does not mean they are completely useless. In fact, kit lens is getting better and better these days that you probably cannot tell by just starring at a photo unless you are looking for it. There are many factors that often people suggest for making decisions on which one to buy, it could be budget, style, skill level etc.
While all of these are true, I would like to humble suggest one thing: your passion level.
A kit lens which worth $100 (Let's just round that off for easier calculation) will be worthed almost nothing when reselling as second hand; while a $1000 lens can last you for years and still hold its value at probably $900 after ten years. In both situation, you end up losing $100 however you gained many nice shot from the PRO lens.
Therefore, if you know you are going to get stuck into photography for years, get the PRO lens. It is well worth it; if you are unsure, then you probably are not passionate and determined enough and I would say a kit lens will serve you well.
Remember: kit lens does not mean they are rubbish! A Mitsubishi Lancer EVO X is a great car and is probably more than most people ever needed, but it can never beat a Ferrari Enzo.