I know similar threads have been posted before but I really feel I need that extra push from all of you. Although price is always a concern for me, I do not want to make my decision based on price alone.


I am leaning towards the f/2.8 but only because I fear that I will always regret not having that aperture if I get the f/4. Outside of that however, I feel that the f/4 has many advantages :
  • Lighter - 26.8 oz / 51.9 oz
  • Cheaper - $1,100 / $1,700
  • Arguably Sharper - "Stopping down from f/2.8 to f/4 will show a difference - and will make this lens very close in performance to the remarkable Canon EF 70-200mm f/4 L IS USM Lens at the same aperture."
  • 4 Stop IS as opposed to 3 Stop IS



At this point I can't say that I "need" the low-light performance of the f/2.8 but when investing this much money I want to cover all of my bases.


I am currently saving up for this purchase and will not be buying either lens in the immediate future.


Current Equipment
  • Canon EOS 50D Digital SLR
  • Canon EF-S 10-22mm f/3.5-4.5 USM
  • Canon EF 24-105mm f/4 L IS USM
  • Canon EF 100-400mm f/4.5-5.6 L IS USM
  • Canon EF 50mm f/1.4 USM



Future Equipment
  • Canon EOS 5D Mark II Digital SLR



Having just reread my very lengthy post it appears that I need to be convinced that the f/2.8 is the right way to go


Oh yeah, either way I want IS so the non IS versions are not on the table.