If you are talking about the first post in the thread it is simply a crop from the first picture, that image was shot at 300mm no extender, Birding becomes an addiction for those of us who are weak minded and penny foolish. I remember wishing that I could afford the first Canon 100-400 and ended up with a good deal on a used lens here at the hog, later I just could not stand that the 100-400 II was better still so I saved and went without a few things and ended up getting that lens again here at the hog.... but that was still not enough, the next was the 500/4... and so it goes, now it was that the Mark II's and III's of Canon's big whites came out and they are better than the older lenses such as my 500.... I ended up with this 300.

The only thing good that I can say about this addiction is that it is better than becoming addicted to drugs and as expensive as it can become it is probably cheaper too.

That's a bit far for me, Haydon … I'm up at the furthest northern point of Fairfield County, just a stone's throw from Putnam County, New York, and about a ten-minute drive from Litchfield County. There are plenty of parks, up, this way, though … along with a very picturesque drive alongside rivers and brooks, where plenty of birds accumulate. Not to mention Putnam Lake and Ball Pond, which both have abundant proliferations of bird wildlife. Plus - Squantz Pond and Kent Falls - both State Parks.

Before buying this lens I did a bit of research on it, it is said by many that it is Canon's sharpest lens. I know that Regis who has owned many of Canon's long white primes had moved to this lens, after talking to him I went ahead and made the purchase. As far as the claim that it is Canon's sharpest lens? I don't doubt that may be true but it is also a pretty short lens for birding and nature so extenders will almost have to be used in many situations. I have been told that even with a 2X extender this lens is sharper than the Canon 600mm, I am not sure that I believe that to be true but I do believe that with the 2X extender this lens is still quite awesome. I own a 500mm mark I and can share some of the advantages of the 300mm lens vs the 500mm lens. Even with the 2X extender attached the 300 is much lighter and more balanced than my 500mm on the camera, while it is true that the 500 can be shot handheld it is a lot of work and not something that most would want to do for any extended period of time, the 300 however is not much different than using the Canon 100-400, a bit heavier but nothing like the 500mm. With a f/2.8 max aperture and Canon's updated focusing system this lens is quick to focus and is spot on.

As far as IQ, below please find an image of a Cardinal the first image is the image that the second image is cropped out of. You can see that even at distance where the subject is presented very small in the image that the amount you can crop is only limited by the sensor, the lens will out perform many of the sensors of the cameras to which it is mounted, this image came from a 5DSR, I am certain that the lens will out resolve the sensor on my 5DIV.