Sorry by this specific question, but I'm pretty crazy here looking for a difference. I've got to buy a lens tomorrow (I leave my country in 2 days) I could see the difference between 55-250 and 70-300, and looking in my country's ebay site, I can found that there is a significant price difference between the Canon 70-300 IS and Canon 75-300 IIi USM Ultrasonic (the second one is half the price)
So... my questions are grouped because I think it them have relation:
1) What is the reason for the price difference?
I think it's because the second one doesn't have IS. Is that it?
2) Is the IS significant at 300mm with 4.0/5.6 ? Some sources said yes, while others said that it doesn't matter. :S Examples in similar images will be really preciated! I couldn't found them in google, I just found examples for L and not L
3) What is the difference between 70 and 75?
By the way, I found that they all have IS in wikipedia :S I really don't understand this. I've got a Rebel T3i.
I found finally a comparison: http://www.dpreview.com/products/compare/side-by-side?products=canon_75-300_4p0-5p6&products=canon_75-300_4p0-5p6_is
And a guy who buys both recommends (for the price) 55-250 IS and the 75-300 without IS. What is the better suggestion, since I can't afford the 70-300 IS right now?
UPDATE 2: The 55-250 lens is EF-S while other ones are EF. Should I take this into consideration?