What would you choose? f/2.8 or 400mm

Hello PotN.

Was hoping to get some peoples insight.

I'm looking into buying a new lens soon and I'm torn between two options.
I currently own the Sigma 70-200mm 2.8 OS and it's my most used lens. I love taking wildlife photos, Zoo photos. Even taken nice portraits with this one.

I'm finding though I would like more reach. I have been drooling over the 100-400mm for a long time. I've borrowed the lens before and I did love it. F/5.6 though seems pretty limiting to me, as I often shoot at f/2.8 - 4 on my current lens.

I've also thought about selling the Sigma, and replacing it with the Canon 70-200 2.8 mrk II and a 1.4 TC. This would give me almost 300mm.
According to this comparison, even with the TC the 70-200 is optically better then the 100-400 at 300mm f/5.6.
Does this seem accurate to people who own the lenses? And what would the quality be like with a 'cheaper' TC option? Would the higher quality remain throughout the focal range with the TC on?

So basically, what do you think would be the best option?

Replace the 70-200 with the 100-400 and sacrifice aperture?

or

Replace the 70-200 with the Canon mrkII with 1.4 TC and sacrifice 100mm, but keeping the ability to go back to f/2.8 when the situation called for it?

Thanks for your input

if you like taking wildlife photos, and that's the majority of use the lens is going to see...go for the 100-400L...don't be afraid to bump up the ISO, and you should be fine with f5.6

Keep the 70-200mm, add the 100-400mm
If you can afford the Canon 70-200mm MkII, than you can add the 100-400mm without selling the Sigma you have. No?
A used 100-400mm is about $1,200.00 ish?

Different lenses, and yes you'd miss the f/2.8
And no, using the zoom with a 2X is not as good as the 100-400mm.

CyberDyneSystems wrote in post #15948574
If you can afford the Canon 70-200mm MkII, than you can add the 100-400mm without selling the Sigma you have. No?

I could keep it, but I think it would end up collecting dust if I owned the 100-400. Every situation I use the Sigma, I think I would choose to take the canon over it. It would be too much weight for me to take both : (

CyberDyneSystems wrote in post #15948574
Different lenses, and yes you'd miss the f/2.8
And no, using the zoom with a 2X is not as good as the 100-400mm.

Yeah, doesn't look like the 2x creates great IQ, but I was thinking just the 1.4x to bring the 70-200 up near 300mm instead. On the lens comparison site I posted above, the tc option was optically better then the 100-400 @ 300mm, assuming it was an accurate representation of the 2 lenses.

Well, if that's the case, than definitely get the 100-400mm.
There's only one way to get 400mm @ f/2.8 and that's a whole other ball game!

By the way, I used to have a 70-200mm f/2.8L IS for events and performance photography, but I like my faster primes, so I sold it.
I kept my 100-400mm for wildlife, and love it.

placidbabe wrote in post #15948594
...the tc option was optically better then the 100-400 @ 300mm, assuming it was an accurate representation of the 2 lenses.

Really, this comparison is pointless since you're just not going to use the 100-400 at 300mm very often and the 70-200 + TC doesn't go to 400mm. If you're going for reach, you get better optical quality and performance out of "native" focal length than by throwing TCs into the mix; especially with zooms.

Feel free to browse through the birds/wildlife images linked from my sig. I shoot 98% of my stuff with the 100-400 and it hasn't let me down yet.

Don't worry so much about f/5.6 being too limiting, either. I shoot in the Pacific Northwest and we don't get "good" lighting here too often, but it's mostly more than sufficient, along with some higher ISOs.

At little more than the 70-200l II you can pick up a Sigma 120-300 OS. This solves both sides of the equation. This comes with a big weight cost. I only use this lens when I know I will have a need for it. In fact I am now saving for a more portable everyday zoom to complement it.

For this reason the idea of keeping your siggy and adding the 100-400 makes sense. No need to take both along every time, just choose based on each occasion.

Good luck!

General rule for a wildlife lens: Get the longer lens even if it is slower.

StarBlazer wrote in post #15948707
At little more than the 70-200l II you can pick up a Sigma 120-300 OS. This solves both sides of the equation. This comes with a big weight cost. I only use this lens when I know I will have a need for it. In fact I am now saving for a more portable everyday zoom to complement it.

Haha. I literally don't think I'd be able to lift that one.
This is where you can't have it all XD


I think I will end up buying the 100-400mm. I mean, I have been in situations where I've been at f/2.8 1/100sec ISO 3200, so the f/5.6 would have been limiting. However, I guess that doesn't happen enough to not get the lens. It is just comforting to know it's there when I need it. But I do think I would use the extra 200mm a lot more then needing 2.8.

I think deep down I did want the 100-400. I just loved it when I had borrowed it. (Though when I used it, bright sunny conditions : P )
It's nice to know other people agree it will be the best lens and I don't think I'll have regrets.

I'll be buying one within the next 3 months Thanks everyone for the help!

If the primary use of the lens will be for wildlife, then reach outweighs faster aperture, IMO. The 100-400L is my "go to" wildlife lens. With the improved high ISO performance of newer camera bodies, the f/5.6 aperture @ 400mm is not as limiting as in the past.

I still own a 70-200 f/4 IS telephoto, as well, as this is used as more of a general purpose, lighter weight telephoto. However, whenever wildlife is a primary focus, I always pack the 100-400L and leave the 70-200 at home.

I have a Sigma 70-200 f/2.8 OS HSM and 100-400L. Completely different lenses for different purposes. I also challenge your assertion that the 70-200 II w/1.4x TC is sharper at f/5.6 & 300mm than the 100-400L. Post some evidence, please.

Which would be better, 100-400 or a 400 f\5.6?

Hulka wrote in post #15950905
Which would be better, 100-400 or a 400 f\5.6?

I may as well do it. Better for what?

Hulka wrote in post #15950905
Which would be better, 100-400 or a 400 f\5.6?

At 400mm the latter; anything in between...

sorry better overall at 400.