Hi InaLisa
A couple of comments on your testing.
First of all the 75-300 does take some beating at the 75mm end of range but it's sharpness does fall off dramatically at the 300mm end.
Shame you did not compare both at 200mm.
The 70-200 L f4 shot to my eye does have the edge on the other 2 shots especially as the lens was wide open @ f4
You will probably find that the 18-55 & 75-300 sharpness sweet spot will be in the range of f8 to f11. The 70-200 L f4 should start to really shine at f5.6.
another factor that expensive lens will have over the 18-55 & 75-300 is reduced colour fringing in bright contrasty shots. ( often seen with trees against a sky or white object is really bright sunlight) The sharpness across the frame ( edge to centre ) will be more consistent.
If the latter are not your problems then concentrate on getting the best out of your exsisting lens. I feel it is better to go through the learning curve to get the best out of your lens and know when and why it has let you down. That way you will understand what a better quality lens is doing for you.
Having better equipment does not gaurantee 100% results if you don't know how to use it.
|