Canon 300mm 2.8L IS mkII with the Canon 1.4x mkIII and 2x mk III teleconverters

Almost all of my wildlife photography (Red deer, Wils Boar, Roe Deer mainly) is in the woods (Europe e.g. Ardennes, Eifel etc) under lower light conditions, often at dusk and dawn. I am using a Canon 7D. I use often the Canon 400 f5.6 a good, but given the conditions, perhaps not the ideal kit.

I am considering to purchase a Canon 300 mm 2.8 L IS MK II with the 1.4X mk III and 2X mk III teleconverters.

Can anybody comment on the performance of this lens, especially with the 2X MkIII teleconverter under lower light conditions? (Most of the images I have seen are made under rather bright conditions). I appreciate that AF speed will be affected (compared to the "bare" lens), does it compare to e.g. the AF speed of a 100-400?

Your inputs are appreciated!

I just recently sold my 300mm f/2.8L IS II but I did use it for about a year with a 7D with the 2X III TC almost exclusively. I also have a 100-400L mounted on another 7D. The 100-400L focuses much faster than the 300L IS II w/2X III TC combo. I was going to try the combo on a 1D mIV to see if I could get a little faster focus for Bird in Flight but decided instead of spending another $3000 for another camera I would sell it and just live with 100-400L. Most of my shooting was early morning or towards evening and I did not see much difference between the 300L IS II and the 100-400L as far as low light focusing except that is was slower. I did find that my image quality with the 7D really started to suffer at the higher ISO's in lower light when needing to keep my shutter speed up. The 4 stop IS of the 300L IS II is very sweet for hand holding and when in shooting in lower light with lower ISO's as long as you have a subject willing to hold still. I tried using it with a 1.4X III TC but never could get acceptable image quality with that combo. When I had the 300L IS II and 2x III TC my 100-400L hardly was ever used except for Birds in Flight. If I could have had a little faster auto focus without having to spend another $3000 I might have kept the lens but I have to admit it sure is nice having that money back for use on other items with a higher priority.

I use the Canon 300mm F2.8 IS Mk1 on my 1D4 with extenders and find it to be an excellent lens. I use a mk2 1.4 extender and a Mk3 2x. With the 2 x extender the AF is noticeably slow, but has proved very accurate, naturally the AF is progressively better with the 1.4 extender or bare lens.
In the case of lower light shooting I find the 300 F2.8 IS Mk1 with the 2 x Mk3 extender is not the best combination, in good light it compares reasonably well with the 600 F4 L IS Mk1 but lags further behind as the light drops. I would expect the Mk2 300 to be a little better but any improvement will be marginal. If you really need these longer focal lengths (and can bear the cost + weight) have you considered the 500 or 600 F4 lenses? A new or used 500 F4 Mk1 or 2 may be just the tool for the job?
I use the 2 x Mk3 extender on my 300 when I cannot get my 800 to the required location due to its bulk and weight, the 300 + 2x is a compromise - but a useful one.
Hope some of the above helps.

I used the extenders on my 300 and was happy with the results. I mostly shot with good light especially using the 2x. Since then I bought the 500 as it is better suited to my wildlife shooting. I do miss the 300.

Just a thought, but have you considered a better low light camera? I have a 7D and a 6D and if I need to shoot in less than ideal light, the 6D is my choice hands down. This was shot handheld on a cloudy day with the 6D and stacked Kenko 1.4x and 2.0x TCs on my 400 5.6. Focal length is 1120mm. ISO 3200, f16, 1/1000s. Manual focus, of course. (But with just the Kenko 1.4x converter, which gives 560mm f8, the 6D will autofocus.) This is also a hefty crop.

Having said all that, the 300 f.28 IS you're thinking about has one huge advantage, and that is the IS. I'm not going to BS here. If I could afford the 300 f2.8 IS and the two Mk III Canon TC's, I'd dump the 400 5.6 in a nanosecond. But you'd still be wowed by the low light performance of the 6D with that shiny new lens.

agv8or wrote in post #16028577
The 4 stop IS of the 300L IS II is very sweet for hand holding and when in shooting in lower light with lower ISO's as long as you have a subject willing to hold still. I tried using it with a 1.4X III TC but never could get acceptable image quality with that combo.

That's interesting about the 300 II and 1.4xIII. I've read a couple of user reviews saying the same thing. In a similar experience I tried both the 500f4/1.4xII and 500f4II/1.4xIII combos. I believe the old combo offered a slightly sharper image. I didn't have the new combo very long, and didn't MFA.

agv8or wrote in post #16028577
I just recently sold my 300mm f/2.8L IS II but I did use it for about a year with a 7D with the 2X III TC almost exclusively. I also have a 100-400L mounted on another 7D. The 100-400L focuses much faster than the 300L IS II w/2X III TC combo. I was going to try the combo on a 1D mIV to see if I could get a little faster focus for Bird in Flight but decided instead of spending another $3000 for another camera I would sell it and just live with 100-400L. Most of my shooting was early morning or towards evening and I did not see much difference between the 300L IS II and the 100-400L as far as low light focusing except that is was slower. I did find that my image quality with the 7D really started to suffer at the higher ISO's in lower light when needing to keep my shutter speed up. The 4 stop IS of the 300L IS II is very sweet for hand holding and when in shooting in lower light with lower ISO's as long as you have a subject willing to hold still. I tried using it with a 1.4X III TC but never could get acceptable image quality with that combo. When I had the 300L IS II and 2x III TC my 100-400L hardly was ever used except for Birds in Flight. If I could have had a little faster auto focus without having to spend another $3000 I might have kept the lens but I have to admit it sure is nice having that money back for use on other items with a higher priority.

This is very interesting and it conflicts with what I have experienced with the 2x III. I used this extender (very briefly) with 200 2.0 (quite similar focus and IS systems with 300 2.8 II) and on my 5d mark III, it focused extremely fast, it could track fast moving objects easily and the image quality was pretty good. You stating the big white is slower than 100-400 to me sounds like it is your 7D that is not up to the job rather than the lens itself. The 300 Mk2 is in a league of its own and I'm surprised you are even comparing it to a zoom that costs nearly 5 times less. Something does not add up.

Perfectly Frank wrote in post #16058439
That's interesting about the 300 II and 1.4xIII. I've read a couple of user reviews saying the same thing. In a similar experience I tried both the 500f4/1.4xII and 500f4II/1.4xIII combos. I believe the old combo offered a slightly sharper image. I didn't have the new combo very long, and didn't MFA.

The 1.4x III with 300 Mk2 should produce fairly sharp pictures.

TheLensGuy wrote in post #16058533
The 1.4x III with 300 Mk2 should produce fairly sharp pictures.

Should? Fairly?

Use a 6D, 5D3 & 1DX with a 300 f2.8 II + a TC III u shouldn't have any issues with AF or quality issues. I shoot a lot on handheld I didn't experience softness but I didn't get to shoot them in very low light but my guess is it depends on the camera in such cases. 300 to 500 to my understanding are handholdable to most photographers who owns them.

I use the 300mm f2.8 IS version 1 with the 1.4x II and 2x III with very good results but the AF is faster with my 1D4. Like anything else you do get better with the lens the more you practice. The 1D series does in my experience drive the lens AF the fastest but that should really not be a surprise as the top of the line AF is in the 1D series cameras. The more challenging the environment the more the 1D AF speed will shine.

TheLensGuy wrote in post #16058533
The 1.4x III with 300 Mk2 should produce fairly sharp pictures.

??? The 1.4x II with the 300 IS MkI does produce very sharp pictures.

Of all the supertelephoto upgrades (to the MK IIs) the 300 f/2.8 would be the last one I would choose. Only a slight improvement in IQ and roughly the same size/weight. (Also you can't remove the foot on the new version.)

The Canon 300mm 2.8L IS mkII is one the best single-lens iv used due to its performnce and versatility for bird photography as its extremely sharp, light and fast AF and performs suberbly with both extenders whilst maintaining AF and IS.

Its a no bainer and well worth the investment.