amfoto1 Loc: San Jose, Calif. USA

Hi Danny,

It depends a great deal upon which 70-200mm f/2.8 lens you have. If it's a Canon lens, there have been four versions (as well as three f/4 versions).

If it's a Canon lens and either the original non-IS version or the first IS version, I would expect image quality to take a pretty noticeable hit. Those two versions of 70-200/2.8 simply don't work very well with a teleconverter, IMO. I used the 1st IS version for many years (great lens on its own), experimented with 1.4X II on it, and found the IQ largely unusable.

The Canon EF 70-200mm f/2.8 IS USM "II" is another matter. It appears to work well with the 1.4X III (and probably the 1.4X II). Perhaps it's because the 70-200mm f/2.8 US "II" has fluorite added (the earlier lenses didn't use it). But for whatever reason, that lens works better with an extender. I don't have that combo personally, but have seen a lot of nice shots done with them.

If you have the latest EF 70-200mm f/2.8 IS USM "III", I have no idea. That lens is relatively new and I haven't seen much done with it yet. In all likelihood, it will work well with a 1.4X extender.

But, IMO, simply buying the EF 300mm f/4L IS USM may make more sense. With the Canon 1.4X III costing $429, you're already a long way toward purchasing the prime lens instead. It's close to halfway toward the typical selling price of a used one in reasonably good condition.... Or about 1/3 the way toward buying a new one. BTW, the 300mm f/4L IS works very well with a quality 1.4X, as a 420mm f/5.6 combo with image stabilization (the excellent Canon 400mm f/5.6L doesn't have IS, unfortunately). I see very little loss of image quality using a 1.4X II on a 300mm f/4L IS.

EDIT: Whoa! You have the EF 100-400 II? You might not need a 70-200 at all.

For many years I've been carrying a 70-200mm f/2.8L IS practically any time I'm out shooting. It's easily been one of my most used lenses for 15+ years. It's certainly been my most used zoom. (So much so that I bought a 70-200/4L IS as a backup). But since getting the 100-400 II I've been seriously considering not carrying a 70-200 at times. There's just so much overlap between them. I've been pairing up the 100-400 with 24-70 more often and don't really miss the 30mm "gap" between them. When I don't need f/2.8, I often use an EF 28-135 IS USM instead (lighter and smaller, but just as good image quality and performance as 24-70 or 24-105L). Obviously, if you want to be able to use the lenses on both FF and crop cameras, you would want to stick with EF instead, but for use on crop camera only I'd also certainly consider either EF-S 18-135mm IS USM or EF-S 15-85mm IS USM... or if a faster lens were needed, EF-S 17-55mm f/2.8 IS USM.

You mention but don't specify which 5D or 7D camera. On 5DIII or IV, or on 7DII, autofocus is possible with 1.4X on the 100-400mm (those are "f/8 capable" cameras). But on earlier 5D models or the original 7D, the lens/TC combo is not able to autofocus (those are "f/5.6 limited" cameras).

I actually now use the 70-200mm f/4L IS I bought as backup, more often than the f/2.8 lens. This is simply because the f/4 lens is about 2/3 the size and weight. It's also very sharp and top performing (fluorite, 3-4 stop IS, fast USM). I haven't tried the 70-200/4L IS "II"... but would assume it's very good too.

jeep_daddy Loc: Prescott AZ

I have the 70-200 f/2.8 Mk II and a 2x Mk III and a 100-400 Mk II. I traded off using these at a raptor free flight show on my 5D Mk IV and the 100-400 Mk II smoked the 70-200 with a 2x in both picture quality, focus speed and focus accuracy. I won't be using the 70-200 with the 2x any more. I do use it on my 500mm f/4 lens once in a while when needed if I need the extra reach but not very often.

imagemeister Loc: mid east Florida

I think it is time Canon made a 1.7X extender !

..

LarryN Loc: Portland OR & Carbondale, CO

I use the combination on a 5DIV & it works great.

DeanS Loc: Capital City area of North Carolina

Chris, we should meet for lunch soon.

Dean

TriX Loc: Raleigh, NC

You’re right Dean, I’ll give you a call after the weekend...

Chris

DeanS Loc: Capital City area of North Carolina

👍👍👍

Danny Nash

All replies are deeply appreciated! One can’t go wrong with this group of photographers!

Have a blessed weekend!