Blurryeyed Loc: NC Mountains.

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.

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CPR Loc: Nature Coast of Florida

That is a very sharp shot. The lens is very capable.

kpmac Loc: Ragley, La

Impressive.

CHG_CANON Loc: the Windy City

My experience with both is the EF 400 f/2.8L IS II is a bit better ... but that would be splitting hairs finer than lines on a chart
And, the 400 puts you back into the size, weight and cost of the 500s / 600s.

olemikey Loc: 6 mile creek, Spacecoast Florida

I like it, if you don't like it, send it to me and I'll buy a Canon body to go with it!!!

Architect1776 Loc: In my mind

This is absolutely amazing.
That has to be one of the best demonstrations of the superiority of this 300mm lens. Can't believe it.
You did a great job handling the camera as well.
Please post other shots with this lens so I can vicariously enjoy it as it is not in my budget.

Chris T Loc: from England across the pond to New England

Neat shot, there, Blurry … so, it looks like a 300 is JUST the ticket for birding, then - huh?

Not sure I quite got your explanation, though. .. Is this WITH the 2x extender, or w/o it?

One more thing, Blurry … quoting you: "I am certain that the lens will out resolve the sensor on my 5DIV."

Have you actually TRIED this lens on your 5D4 yet, or not?

I would be most interested (as I'm sure would we all) to see shots taken with this lens, with BOTH your 5D4 AND your 5Ds R - side by side. Do you think that might be possible, Blurry?

Blurryeyed Loc: NC Mountains.

That shot is without the 2X, when I say out resolve, I am quite sure that you will see pixilation before loss of detail on the Mark IV, making that call based on what I am seeing on the 5DSR. I did some comparison shots of the back of a cloth backed patio chair with the 2X and without the 2X, I can post them here for you and let you be the judge... The first is a crop with the 2X and the second is without. You can download them and judge them for yourself... I figure that I will be using my teleconverters more often than not, but it is kinda a no brainer that the images are cleaner without them but 300mm is often just not long enough for birding, the big question for me is will I be using the 1.4X or the 2X as my goto converter.

With 2X

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RichardTaylor Loc: Sydney, Australia

From personal experience:
300mm can be ok for birds that are used to people. (Say in an urban enviroment).
However 400mm a is a much better starting point for a lot of birds. Sometimes, especially when shooting in the wild you cannot have too much.

Chris T Loc: from England across the pond to New England

Okay, Blurry - so, where's the one done with the 1.4x?

BTW - are you saying - we'd be SO uncomfortable, looking at a shot taken with this lens, and the 5D4 - it wouldn't be practicable - to even POST one?

Blurryeyed Loc: NC Mountains.

I also have a 500/4, the 500/4 is a bit much for handheld or a walk down a nature trail, set up on a tripod with a gimbal it is fine, this lens is much better for a walk through the swamp.

Blurryeyed Loc: NC Mountains.

I am not sure what you are asking, but I think that I was saying that the 500 is just too big for a nature walk, a bit uncomfortable to shoot handheld. The 300 with the 2X gives a 600mm f/5.6 that is still sharp and is easily handheld, the 500 really wants to be on a tripod with a gimbal. The 300 is without a doubt the sharper of the two lenses but tele extenders do impair the IQ, I have not yet done comparison shooting of the 300 with the 2X vs the 500 by itself or the 1.4X extender.... I have time but like I said, a 500mm lens is a big piece of glass and very imbalanced on the camera. The image below is the 500 with an extender. It is too much lens to take on a walk.

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Chris T Loc: from England across the pond to New England

Okay, Blurry … so - a comparison of the 2x and 1.4x extenders on the 300, is in the works, then.

Never mentioned the 500 … not sure how that mention got into this response. Perhaps, THIS part, should be directed at Richard, then - who DID mention the 500 - I believe.

But, I DID mention, for a second time, the idea of posting shots taken with this 300 and both cameras - so we could see what happens with the lesser RES camera (5D4) when the lens OUT-resolves the sensor.

Whoops!!! … Sorry, it wasn't Richard who mentioned the 500 - only you. Richard mentioned only that 400 would be more appropriate with birds. Actually, you'd have 420 with the 1.4x - which really isn't enough for most bird shots, IMHO - you really need 600 - don't you? (this particular shot, aside.)

It's a shame that 500 is too heavy to take on walks. That would be ideal, were it lighter - huh, Blurry?

Architect1776 Loc: In my mind

Just ignore Chris at this point is my suggestion.
Your photo looks great and the purpose of the post is understood by the rest of us.
Don't get into the weeds on the Chris crap.

TriX Loc: Raleigh, NC

It’s an excellent lens (my son has one) and I can attest to the fact that it works very well with a Canon 1.4x MkII or MKIII extender and the 5D4, but haven’t tried the 2X. I’ll be interested in seeing your comparisons...

Congrats.