Want your telephoto lens to be a little MORE “telephoto”? Here is an option to consider. You could buy a teleconverter. This device inserts between your camera and the lens, and extends the effective focal length of the lens. Most often, you will find these as 1.4X and 2X teleconverters.
As with all things, with the benefit comes some tradeoffs. You have to be really careful in your selection of a teleconverter and read lots of reviews before purchasing, otherwise you could be really disappointed.
One tradeoff is you lose one stop of light with a 1.4X teleconverter and you lose two stops of light with a 2X teleconverter. Also, depending on the teleconverter, you’ll have varying degrees of degradation in image quality. With some teleconverters attached to some lenses, you might even lose other features like auto focus! So, before you buy, do your homework.
I thought I’d share some observations with a teleconverter I own. I use Canon cameras and they call their teleconverters “extenders”. (They just had to be different from everyone else, don’t ask me why.) I own the Canon EF 2.0X III Telephoto Extender for Canon Super Telephoto Lenses.
I happen to own these two Canon telephoto lenses:
I absolutely love both of these lenses. The 70-200 is literally one of my all-time favorite lenses I have ever used over my 40+ years in photography. And the 100-400 is an excellent lens for use in my wildlife photography, for example on our Rocky Mountain Photography Workshops we host in the Summer and Fall.
We shoot with both of these lenses, and sometimes use the Canon 2.0X Telephoto Extender on the 70-200 lens, to extend its focal length to 140-400mm. This really works pretty well.
I would most definitely not recommend you use the 2.0X Extender on the 100-400mm lens though. That is not a good combination, primarily because the auto focus system will not work, plus the images turn out a bit too soft. But the 70-200 is quite nice with the 2.0X Extender. If you shoot with the 70-200, you can keep the 2.0X Extender in your camera bag to boost the focal length when you need it without lugging all that extra weight of the 100-400.
Also, if you already own the 70-200, buying the Extender would be the cheaper alternative, rather than purchasing the 100-400.
When you use the 2.0X Extender on the 70-200, you’ll note that it shifts from being an f/2.8 maximum aperture to being f/5.6 (which is two stops down from f/2.8). That’s really not bad at all. It is comparable to the 100-400 which is also at f/5.6 when you zoom to 400mm.
Let’s look at the two setups side-by-side. The one on top is the 70-200 with the 2.0X Extender. The one on the bottom is my 100-400.
The overall length is about the same when zoomed to 400mm, although when zoomed down to their lower focal lengths, the 100-400mm is more compact.
Here are some comparison shots, done with these two combinations.
Here is a shot done with the Canon EF 100-400mm f/4.5-5.6L IS II USM Lens set to 400mm:
I noticed the 100-400 rendered ever so slightly warmer toned images compared to the 70-200 with the 2.0X Extender. I also noticed that the 70-200 at 200mm and adding the 2.0X Extender actually enlarged the image a little more than the 100-400 at 400mm. They were not exactly equal at effectively at 400m. I was really a little surprised at that.
When I cropped in closer on the two images, I found the 100-400 at 400mm yielded the sharpest results, but still the 70-200 at 200mm with the 2.0X was not bad at all. I consider the two scenarios to not be exact equals, but quite acceptable (enough that I own the 2.0X Extender and I intend to keep it.
Here is the enlarged cropped-in version of the Canon EF 100-400mm f/4.5-5.6L IS II USM Lens set to 400mm:
And here is the enlarged cropped-in version of the same shot done with the Canon EF 70-200mm f/2.8 L IS II USM Lens with the Canon EF 2.0X III Telephoto Extender extending the focal length to an effectively equivalent 400mm:
So, the bottom line is: I am pleased with my Canon EF 2.0X III Telephoto Extender at least when using it with my favorite lens, the Canon EF 70-200mm f/2.8 L IS II USM Lens! If I want the sharpest shots at 400mm with my Canon lenses, I’d have to go with the Canon EF 100-400mm f/4.5-5.6L IS II USM Lens.
Oh, by the way, make sure if you buy any of these items, note the “II” designations on the lenses and the “III” designations on the Extender. Those indicate different versions of these items. The “II” versions of my 70-200 and 100-400 are truly wonderful, outstanding lenses with excellent image stabilization. I am totally happy with both of these remarkable lenses.