I have been wanting to get an L lens for quite some time. I've been seriously considering the 24-105mm, but I'm not 100% sure I can truly be happy with f/4. So then I look at the 28-70mm f/2.8, and I can't justify the price vs the 24-105. I use the-digital-picture.com's Lens Image Quality tool as my guide for IQ, and I see little to no increase in IQ between the two (certainly not $1k worth).
A few months ago, I picked up a first version EF 100mm Macro for dirt cheap because the switch fort he AF/M was missing (I use my fingernail). It is truly an amazing lens. Every image seems to have that '3D pop', there is zero CA/fringing, sharper then a sharp tack, and great colors and contrast.
My other lenses are the kit 18-55mm IS II, which is a great lens for the money, but it's a little on the slow side at 3.5-5.6. The 55-250mm, which is also a great lens for what it is, but the same issues (speed). The 50mm Mk I (I hardly use it, but have to have it). The 85mm f1.8, which I abhor. The CA/fringing kills anything positive about this lens for me, and I haven't touched it since I got the 100mm. So really, I have two good kit lenses, and three 'standards' in the 'better' quality. I also have the Wigma (10-20mm), and a Tamron 200-400mm (decent, but not the world's best). Then I have a slew of MF lenses that are just awesome (Super-Tak 1.4, Biotar, Helios, S-K Xenon, and others that are just for fun).
I have read enough times hear and elsewhere that the 55-250mm when processed correctly, can hold it's own to the 70-200mm L. I honestly see very little IQ increase between the 18-55mm and the 28-70 or 24-105mm's. These two considerations make it very difficult, for me at least, to jump into the L ring circus. What am I missing about these lenses?
If the 24-105 (or the 28-70), or the 70-200 give results like the 100mm macro, I wouldn't think twice, and get them. But from everything I see and read, I think I would be disappointed.
Is there a lens or lenses that can give me what I found in the 100mm? While price isn't the end-all be-all, I wouldn't want to go over $2200 per lens.



At f/8 your not going to see too much of a difference, especially if your shooting buildings and interiors. You will however see a difference in distortion. 

