Here is a Canon RF 100-500mm review. The recently announced Canon RF 100-500mm f/4.5-7.1L IS…
Photographer Dustin Abbott reviewed one of Canon’s affordable telephoto lenses, the recently updated Canon EF-S 55-250mm f/4-5.6 IS STM lens. While the EF-S 55-250mm f/4-5.6 IS STM is a budget lens, the optical performance of this lens is very good.
From the conclusion (emphasis mine):
If you have a limited budget but need a telephoto lens there is really no need to look any further. The Canon EF-S 55-250mm f/4-5.6 IS STM gives a lot of performance for its relatively low purchase price of right around $300. The redesign of its optics makes it a legitimate competitor of much more expensive options, and, while it may lack the higher grade build of those lenses, it is actually surprising how close this lens comes in optical performance. It really doesn’t have a lot of optical weaknesses other than being a little prone to veiling when the sun is in the frame (at telephoto lengths) […] The maximum apertures at most focal lengths suffer relative to competitors, but the great wide open image quality as means you don’t have to stop the lens down as much. The build quality isn’t impressive, but it’s not terrible, either, and the lens handles fine overall. I found the image stabilizer to be effective, and, while STM focus is not my favorite AF system, the lens performed quite ably in most situations.
You may watch the 12 minutes video above or head over to Dustin Abbott’s site for the review and a huge set of sample pictures shot in real world settings.