crazydaddio Loc: Toronto Ontario Canada

I have the C not the S.
When I did my research (Google), there was some debate about whether the S was worth the penalty of weight and almost double the cost...went with the C. Consensus feedback had the S better at 600mm but otherwise was negligible.
100-400 (either I or II) will have better IQ and at F4 ... better versatility in lower light.
The Tamron G2 feedback suggests its better than the C and almost as good as the S at 600mm....but with a slight cost increase.

In general 100-400 F4L ii is the best choice in my opinion IF you have the cash.
If you are just shooting BIF or sports on sunny days the Sigma C is a great choice for the price.
70-200 on an extender is the cheapest option but much debate about flexibility, AF stop-loss, actual IQ etc. As some have noted, Regis has taken some spectacular pics which for me settled the debate about sharpness. AF, flexibility, camera body etc etc remain.

Net: If you want good IQ at 400mm for the lowest cost get the 2x iii extender(assumes you have already spent the big bucks on a 70-200 2.8). If you want extra reach, with guaranteed AF on all bodies, get the Sigma C or Tamron G2.
Biggest cost, best IQ and most reach, crack open the kids piggy banks and get the 100-400mm L ii and the 2x iii extender. It will work all the way to 800mm on center AF pt on your 5DmkIV but I cant comment on how fast the AF is. (My C is very fast on both my 70D and 5dMkiv. Shot football, BIF etc and it was excellent....and on the 70D its over 900mm equivalent!

If you want to break your back ...get the Sigma S :-)


....so much fun deciding....

Attached a photo. 150-600mm SigmaC, 70D, f6.3, 2000ISO, 1/1600 350mm equivalent, cropped about 40%.

billnikon Loc: Pennsylvania/Ohio/Florida/Maui/Oregon/Vermont

I never have liked extenders of any kind, If I were you I would go with the Canon 100-400 II version, it is an outstanding lens, and I am a Nikon guy, wish they made one as good.

Architect1776 Loc: In my mind

I have the 2x and the 100-400 MII. If you can afford it get the 100-400. Focuses to slightly less than 3' at 400mm. That is approaching macro capability and far better that any other zoom in that range and that includes the 70-200 lenses too.
The 2x on your 70-200 will work very well with virtually no loss of quality with the MIII version so you can save a lot of money to get 400mm. The problem is you need to change lenses with the 2x to get 400mm where with the 100-400 you get nearly the same range of focal lengths in one lens and no changes required. Keep the fast 70-200 for low light but I would go the 100-400 if budget allows and it will become your go to general purpose telephoto lens except in limited dark situations.

Largobob

Good basic information. Thanks for sharing.

imagemeister Loc: mid east Florida

Yes, since you already have the 70-200 BOTH extenders are viable and, they need not be Canon extenders ( $$$)

markngolf Loc: Bridgewater, NJ

I use the 2X III with the Canon 70 - 200 f/2.8 II. IQ is still excellent.
Mark

ronjay Loc: york Pa.

I shoot the 7d markII with the Canon 100-400 II great images with a min 32 inch focus. I also have tha 1.4 III extender. Which really draws draws it closer. I see no IQ loss and is lighter than my Tamron 100-600 lens. Also great auto focus with the extender at f/8. Winner winner !!

Notorious T.O.D. Loc: Harrisburg, North Carolina

Notorious T.O.D. Loc: Harrisburg, North Carolina

The 100-400 II only has a magnification ration of 0.31... not near macro. But you can get some fairly good close up shots if you are willing to crop. I do the same with my 70-200 and the 2.0 TC III. The one thing that I don't really care for on the 100-400 is the external zoom...but it is an excellent lens and value.

Best,
Todd Ferguson

jeep_daddy Loc: Prescott AZ

Ditto!

I have this combo and it works excellent.

I also have the new 100-400mm Mark II lens and it's great too.

Either way you go, you can't go wrong. With the 1.4x III on your 70-200mm you'll have a 280mm lens at f/4 which is a little shy of the 400mm you'd get with the long lens.

TriX Loc: Raleigh, NC

The 100-400L MkII is a fabulous lens and an improvement over the MKI, but if the 2K$ price is unworkable, consider the MKI version. It is a push-pull zoom (which you either like or you don’t), and not quite as sharp as a MKII, but it’s still an excellent lens and be had used in the $1,000 range.

amfoto1 Loc: San Jose, Calif. USA

It depends A LOT on which 70-200mm f/2.8 you have....

The non-IS and the original IS do not work all that well with teleconverters. With those 70-200s even a weaker magnification 1.4X, including high quality TCs like Canon's own, will make for a combo that produces more marginal image quality. On both those lenses, I wouldn't recommend 2X at all.

The 70-200/2.8 IS "II" is another matter... It works very well with a good 1.4X and a lot of people find image quality acceptable with a high end 2X (such as Canon's "III").

Either version of 100-400mm used without any teleconverter would give better image quality, no doubt about it. But as an f/5.6 lens from around 300mm and longer (f/5 between roughly 135mm to 300mm, f/4.5 at 100mm), you are losing 1-1/3 to 2 stops of light, compared to your f/2.8 lens. This might be a real consideration if shooting indoors. The f/2.8 lens will focus faster and allow for higher shutter speeds and/or lower ISOs. I use the 100-400mm "II" primarily outdoors in good daylight.... when I'm shooting indoors in more challenging light I switch to f/4 and f/2.8 lenses.

You would be wise to keep your 70D for this use, regardless what lens you choose. Or upgrade to an 80D. The APS-C cameras essentially give a "free 1.6X teleconverter". By "free" I mean there's no light loss.... f/2.8 is still f/2.8 with it. If you were to crop your 30MP 5DIV images to the same dimensions as the APS-C camera, you'll be left with an 11 or 12 MP image. Using the APS-C camera instead gives you 20MP (or 24MP in the case of the 80D).

BTW, adding a teleconverter also slows AF a little (1.4X) or a lot (2X)... which can be problematic with active subjects.

crazydaddio Loc: Toronto Ontario Canada

unlucky2 Loc: Hemet Ca.

The canon 400L 5.6 without IS can be found for around $800 and will solve the reach problem on both your cameras. The Yongnuo 2x III is a knock off of the canon 2x III and costs less than half. The 100 - 400 mk II is sharper than any of the 150-600 weighs less and has a minimum focal distance of 3'. So as to image quality.... the 100-400 is hands down the better

Same bird (American Kestrel ) 7d with 400 L 5.6 and Yongnuo 2xIII on 7D (f11 iso around 250) and 100-400 mkII on 5DSR crop to same size image

(Download)

Retired fat guy with a camera Loc: Colorado

I just posted this, to a should I get a 1.4 or a 2 earlier.
If you want to keep your images sharp, do not buy a extender. I had both, a 1.4 and a 2. The 2 was awful and the 1.4 was nearly as bad.
Save your money, buy a good pair of comfortable shoes, and walk closer to your subject. You will save yourself a whole lot of anguish.
I used mine with a Canon 1Ds Mark lll, a older camera, but still a pro body, and a 300 mm non IS L . Which according to all that is holy, sharper than the IS. A pretty good combination for a tack sharp image. And, without the extenders it is. With them Trash.
There is no way to recover a bad image, photoshop can do only so much. I know I have tired.
Oct 14, 2017