Moderately better image and other benefits

John Crowe wrote:

Fair enough. I did love my much less expensive 400/2.8 for 14 years so I did not mind only using it for 2 months of the year. It certainly is not a lens you pull out for the heck of it.

I have noticed a lot of conversation about sharpness. For the record 400/2.8 lenses are much sharper than 300/2.8 but they are also much heavier and much more expensive and as you say much more limited use.

I had the 400mm f2.8 Mark I for a few years but I sold it because I hated to see the thing sitting around so much. I dragged the heavy lens to volleyball games and shot from the rafters even when my 300mm was easier to use and more practical for that purpose.

When you can, I have found it is worthwhile to stop the lens down one additional stop when using teleconverters, even if it means nudging up the ISO by one stop. You essentially get the lens back to its bare sharpness while losing a bit in ISO. When doing so the 300/2.8 becomes a 420/5.6 or 600/8 depending on teleconverter. Even without teleconverters I try to stop down one stop if I can shoot at the same ISO, since these supertelephotos do get even sharper when closed a bit.

Unfortunately our multi-use field has a lot of clutter in the background (cars, fences, power lines, field maintenance equipment, etc.) that I would really like to throw out of focus as much as possible.

While the ultimate test on how useful a lens is, is in actual use and seeing real world comparable results, the best way to test for sharpness is of static subjects under good light and from a tripod with confirmed manual focus. I always test first and then look for improved results in real use.

But if I don't get improved results in real use, then why waste my time doing irrelevant tests? I have taken literally tens of thousands of sharp action photos with other lenses so why wouldn't I get sharp action photos with this lens?

I am sure you will enjoy putting the newer 300/2.8 to good use!

It will be doing exactly the same stuff the older 300mm f2.8 was doing. I am looking forward to it being lighter since that old lens get very heavy to pick up by the fourth quarter of a basketball game.