20mm vs 20-50mm comparison
Here is a brief comparison for you between the 20mm and 20-50mm. I used a tripod, shot RAW, processed both images exactly the same. I cannot tell the difference between the 2 shots in terms of IQ, colour, or sharpness. There is a very slight difference in the overall field of view between the 2 lenses, which I would attribute to the zoom elements of the 20-50. I find the 20mm is excellent a close focusing though.
The third pic is my trusty old Nikon D50 with a Tokina 20-35mm lens which I picked up for less than $100; however it is an monster of a lens and I could easily use it as a deadly weapon, or do bicep curls with it to get a good workout. The processing with this pic is identical to the Samsung ones.