300mm f2.8 IS vs 400mm f4 DO WIDE OPEN

Looking at buying either the 300mm f2.8 IS Mk1 (not the new Mk II too expensive) or the 400mm f4 DO. I currently have the 70-200mm f2.8 IS MkII with the 1.4X MkIII TC and I am looking to replace my older 400mm f2.8 Mk II non IS lens because it is too heavy to carry far. I am thinking of the 70-200mm with the 1.4X gets me to 280mm and the 400mm DO with the 1.4X would get me to 560mm, and that is what I have right now as far as focal length and I am Ok with that since I can usually get quite close to wildlife. The problem I have is with light, for much of the year it is less than ideal so that is why I want and need a fast lens. Wanted to see what people thought of using their 400mm DO lenses at f4 (WIDE OPEN) at f4 and how it handled the 1.4X wide open at F5.6. I know the 300mm at f2.8 wide open is sharp and it handles the 1.4X nicely, but I think I would like the added focal length. I always shoot raw so the contrast issue of the 400mm DO lens should not be an issue if there is any. The 500mm would be nice but I want a lens that is smaller, doesn't take up the whole bag and is light to carry, I am often hiking in the mountains or snowshoeing through the woods, so weight is the main issue.

it's light vs focal length. you'll have to decide which is more important. i'd go with the 300, that lens is one of their best.

Upgrading body is another option.

Talaska wrote in post #13718913
weight is the main issue.

Which would point towards the 400 - over half a kilo (1.3 lbs) lighter.

I don't normally link to the digital picture samples but it's worth taking a look.

300+1.4x vs 400 DO, both wide open: http://www.the-digital-picture.com …omp=0&FLIComp=0​&APIComp=0

Looks much the same, DO a touch better. DO certainly better at the corners but on an APS-H body shooting wildlife I assume that wont matter much.

300+2x vs 400 DO+1.4x, both wide open: http://www.the-digital-picture.com …omp=0&FLIComp=1​&APIComp=0

DO perhaps a little better in the centre but worse in the corners in this instance.

Keeping in mind that those are from a 1Ds3. You'll have more dense pixels than that so pixel-level sharpness on your body wouldn't be quite as good as those samples.

Based on those it's a close call IMO, especially if you factor in a little sample variation. What that doesn't tell you:
- How the AF compares in those various combinations
- Dimensions/weight/etc
- The fact that the 300 F/2.8 can also be used as a 300 F/2.8. If light is fading you can drop to 300mm and try and get closer or just go for a looser composition.

I can't speak to the 300/2.8L but my 400/4DO takes the 1.4x Mk III really well. It is acceptably sharp wide open and very sharp when I close it down half a stop.

I find the IS is ok (iirc its second generation) but I get far better results if I use a monopod or a Wimberley Sidekick when I'm in a hide.

The 70-200 /2.8L Mk II also works really well with this tc however it was not quite as sharp as my300/4L.

If portability is really of great concern to you, I suggest you consider the 400DO.

I went through similar debate recently (see here: https://photography-on-the.net …howthread.php?t​=1132716); eventually I got the 300 f/2.8 II.

The 300 f/2.8 II is the smallest and lightest of the L superteles (you may argue that 300mm is not really "super", but it is one of the "big whites" nonetheless), but it is not small or light. The older version is even a little heavier.

The 400 DO is really a very portable lens; with a quality 1.4 TC, it should be very capable. Once my wallet has repaired itself , I may grab a used copy.

I'm not familiar with the 400 DO but the 300 wide open is excellent. When I attach a 1.4 tc quality stays high. One of Canon's best.

Thanks everyone for the reply's. It was nice to see the test results and the reply's from those of you who own this lens. I think I am going to try the 400mm DO because of the weight and also being able to go to 560mm with the TC. I know the 300mm would be sharper but with a 1.4X TC attached the straight 400mm will have better IQ, and if I need f2.8 I will use the 70-200mm. Now to start looking.

Please let us know how you get on. My friend is seriously thinking about selling her 300 f2.8 and getting the DO instead.

phreeky wrote in post #13724709
I don't normally link to the digital picture samples but it's worth taking a look.

300+1.4x vs 400 DO, both wide open: http://www.the-digital-picture.com …omp=0&FLIComp=0​&APIComp=0

Looks much the same, DO a touch better. DO certainly better at the corners but on an APS-H body shooting wildlife I assume that wont matter much.

300+2x vs 400 DO+1.4x, both wide open: http://www.the-digital-picture.com …omp=0&FLIComp=1​&APIComp=0

DO perhaps a little better in the centre but worse in the corners in this instance.

Keeping in mind that those are from a 1Ds3. You'll have more dense pixels than that so pixel-level sharpness on your body wouldn't be quite as good as those samples.

Based on those it's a close call IMO, especially if you factor in a little sample variation. What that doesn't tell you:
- How the AF compares in those various combinations
- Dimensions/weight/etc
- The fact that the 300 F/2.8 can also be used as a 300 F/2.8. If light is fading you can drop to 300mm and try and get closer or just go for a looser composition.

Having used two 400 DOs and owning a 300 2.8 IS, I'd say that the 300 2.8 is sharper at f/4 with a 1.4x attached. Contrast is obviously better on the 300. My first 400 DO was pretty bad, and the most recent copy was very good--still wasn't as sharp as the 300 @ 420mm.