Thank you for answers everybody, I understand GAS etc., however would you argue that if I bought a better lens like lets say 24-105L it would improve the overall quality and sharpness of images? Is that not a good addition to developing and appreciating photography more?P.S Forgot to mention I do have a very basic speed light with TTL, which does allow to create absolutely new edge of photography
That's a great question. Let's talk about lens sharpness.
You've got a Canon T3. That's a 12.2 megapixel camera.
Ask yourself these questions:
Do you make physical prints of your images or do you view them on a computer monitor?
How large are the images when you view them?
We'll just pick a few sizes. I have a 27" monitor ... which is a nice size monitor. The resolution is 2650x1440. That's about 3.8 megapixels.
If we print an 8x10 at 300dpi, that's 7.2 megapixels.
But you have a 12 megapixel camera. That means you are usually NOT using all available data when looking at images.
So back to the lens question. Is the 24-105 "sharper" then the 18-135? It turns out the "MTF" curve between the two lenses (the 18-135 "STM" is noticeably improved over the 18-135 non-STM) are very close. The "MTF" curve is a graph which plots lens sharpness at various distances from center axis out to the edge. It'd be hard to argue that the 24-105 is noticeably better. But the REAL question is not whether it's better... it's whether it is SO MUCH better than you'd *actually* be able to *see* the difference when viewing on your monitor or the prints that you produce.
And the answer to that question (would you notice the difference?) is ... not likely.
The 24-105 is intended as a "kit" lens for a full-frame body. While it works on a crop-frame body such as your T3, you'll find it's not very wide at the "wide" end of the zoom range.
The 50mm f/1.8 is "sharp", but has poor quality background blur due to it's 5-bladed aperture diaphragm. Also it's build quality isn't particularly good and it's focus motor is slow and noisy (not good for fast action). But its in-focus quality is just as good as the other 50mm lenses that are available. The 50mm f/1.4 is the favorite but it's not actually "sharper" in the in-focus areas... it's that it has a better build quality, a faster focus motor, and it's image quality in the out-of-focus areas is smoother.
The EF-S 55-250... now here's a lens I can completely understand wanting to upgrade. The 75-300mm probably has the reputation for being the most marginal quality telephoto zoom Canon makes... the lens is designed to be cheap and it shows in performance. The 55-250 is the EF-S budget zoom. It's actually a *little* nicer than the 75-300... but not much. The contrast is poor and frankly I actually gave my copy away -- I was never thrilled with that lens.
Based on how you describe your shooting, I'm not sure I'd be in a hurry to replace the 55-250 because it sounds like you very seldom are in situations that call for a telephoto zoom.