Canon 300mm F2.8 USM IS Soft focus

[limvo05]

Hello,

While searching for a great deal on the Canon 300mm f2.8 IS mark I, I came across a few reviews suggesting soft focus issues with this lens. I was wondering if anyone experiences the same? Is this an inherent problem with this lens or luck of the draw? Below are some of the comments found on B&H site.

Unreliable and soft focus

Bymurphyslaw

After owing this lens for more than 3 years and struggling with the soft focus issues, I am now convinced that this lens has inherent quality issues and even after a tune up by Canon, i am still seeing soft focus issues inconsistently. I tried the several lens tests on a tripod, however, could not get a consistent result. Now looking at others who have similar issues, I am convinced that this is a faulty product, or atleast I have a lemon. Shame on Canon for producing such flawed products in the top of their product line.

------------------------------------

I was excited to have this lens, as a wedding photographer working in many low light situations --- my excitement was VERY quickly dashed. I used this lens at 1 wedding, and while I managed SOME photos that will be salvaged, the majority of the shots were MUCH softer focus than I want for my clients. Canon makes amazing equipment that I stand behind 100%.....THIS Canon lens is NOT something I can get behind.

[ebiggs1]

"There are times when f2.8 vs f4 does make an important difference:"

Absolutely and exactly why you buy the lens that fits your requirements and needs. The main and only most important consideration. 

[ebiggs1]

"That said, have you seen what they do with your luggage?"

I worked for and traveled for a large maybe the largest photography company there is.  What I have tried to advise you is from that experience. I know one of my co-workers that lost all their gear on one trip.

Canon makes these kinds of lenses especially for that kind of work. Canon is well aware of baggage handlers and shippers believe me.

I have seen guys throw their big lens in the case and not from an inch or two but feet away.  I have seen guys sit on their lenses and more.  The average Joe just does not need that kind of build.

[Waddizzle]

"Depending upon the body, a f2.8 or faster lens will activate dual cross point sensors in the AF array providing for the highest AF performance from that lens/body combination."

I don't think f/2.8 is set in stone.  Before I gave it away to my son, I think my EF 24-105mm f/4L IS USM would enable, let's call it wide aperture mode, with my 6D.  The firmware seems to make exceptions for many of the f/4L lenses.

Note, this does not mean all f/4 lenses, just the Canon L glass f/4 lenses.  I guess I need to look it up to confirm if the 300 f/4L activates the f/2.8 wide aperture mode, but I would strongly suspect that it would.

Just like teleconverters are designed to work primarily with telephoto primes, the firmware allows exceptions with many L glass telephoto zooms, like the 70-200s.  Activating "wide aperture mode" is permitted in firmware with many f/4L lenses.