Let's have a look at the Canon Extender EF 1.4x II. It's a teleconverter that multiplies the focal length of a lens by 1.4. It turns a 300mm lens into a 420mm, a 70-200mm zoom into a 98-280mm, a 100-400mm into a 140-560mm, and if you attach it to Daniel Radcliffe he becomes Elijah Wood.
I was curious to see what it was like with my Canon 300mm f/4 IS. A 1.4x teleconverter turns the 300mm f/4 into a 420mm f/5.6, which is essentially the same as the Canon 400mm f/5.6, but with image stabilisation and a closer minimum focus distance. Are the results any good? Yes, surprisingly so, although I can't compare the image quality directly with a 400mm f/5.6 because I don't have one.
It's Brad Pitt, again, shot with a 300mm f/4 IS + 1.4x MkII at the 2019 Venice Film Festival.
These people were much closer, and didn't need teleconverters.
Teleconverters are controversial. There has always been something grubby about them. They're a lot cheaper than going up a focal length, and you can choose not to carry around the extra weight and bulk of a longer lens, but on the negative side they exaggerate a lens' optical deficiencies and add some of their own, and furthermore they take away some of the light.
A 1.4x teleconverter turns an f/4 lens into an f/5.6 lens and a 2x teleconverter turns the same lens into an f/8, which is awkward because some camera bodies have trouble focusing with dim lenses. If it's a bright sunny crisp clear beautiful lovely day and the birds are singing a pretty song and there's music in the air the loss of light isn't a huge problem, but what if you live in England?
What happens is that people buy the cheapest telephoto lens they can afford because they feel they need a telephoto lens, and then they decide to try out birdwatching or something, but the lens isn't long enough, so they buy the cheapest 2x teleconverter they can afford, and the end results look awful, so teleconverters get a bum rap.
You and I are not like them, we are better. I'm fortunate to have such good readers. For this post I used a moderately long teleconverter with a very good lens in optimal conditions, and the results were good, as I will demonstrate in just a few short paragraphs.
The MSC Musica. It has a giant video screen so that you can watch television while floating in the pool.
This is not Brad Pitt.
So far Canon has released three 1.4x extenders for the EOS range, alongside a parallel range of 2.0x models. The original came out in 1988; the Mark II version came out in 2001 and added weather sealing; the Mark III was released in 2010, and had a different optical layout and improved anti-smear coatings.
Each mark is apparently optically and electronically better than the last, although from the tests I have seen on the internet the difference is very small. The Mark II version stands out on the used market because it's not much more expensive than the Mark I, and it's the oldest model with a weather seal. The seal only makes a difference if the lens itself has rubber gaskets - the 300mm f/4 doesn't - but I have other lenses.
A 1.4x MkII attached to a 300mm f/4 IS.
Of note Canon's teleconverters only work with certain lenses. Consider the following image:
On the left is the 1.4x, on the right a Canon 100mm f/2, which would become a 140mm f/2.8 with a 1.4x teleconverter. As you can see the 100mm f/2's rear element is too close to the mount for the lens to physically connect with the teleconverter, and the pin arrangement is slightly different.
In contrast the 300mm f/4 has more than enough space for the 1.4x to fit, and it has the right number of pins:
There are complexities. Third-party teleconverters from Kenko and Sigma etc have a different physical design that will attach to the 100mm f/2, although I have no idea how well the autofocus works. Canon's extenders generally work with all of the longer L-series zooms and primes, but there are a handful of exceptions, notably the Canon 28-300mm f/3.5-5.6L, which has an inner lens tube that hits Canon's extenders when zoomed out wider than 50mm or so. Canon's Mark II 1.4x and 2.0x extenders can be stacked on top of each other, but I surmise that the results would not be pretty.
In theory the 1.4x reduces the camera's autofocus speed, but in practice with my 300mm f/4 the speed went from being very fast to being merely fast, so I didn't notice any difference. The image stabilisation continued to work.
What's it like? Is it sharp in the middle? Yes, or at least sharp enough. Contemplate the following images:
I have no idea who these people are. Perhaps they're famous in Italy. At the top is the whole frame at 420mm f/5.6 shot with a Canon 5D MkII, at bottom is a 100% crop, without any sharpening.
Here's St Mark's Square, also at 420mm f/5.6, ISO 100, with image stabilisation, off the top of my head 1/180th or so:
The lack of contrast probably has more to do with the dim light and distance than the teleconverter. The top-left corner has some CA, but with Photoshop it could probably be massaged into something decent, and it has to be said that unless you're doing astrophotography the corner will be out of the plane of focus most of the time:
The centre is fine, although again it might benefit from some sharpening, noise reduction, and a contrast boost:
The combination of 420mm and f/5.6 doesn't lend itself to blurring out the background, unless the subject is very close:
I mention that teleconverters exaggerate a lens' deficiencies. The 300mm f/4 IS tends to have purple-red colour fringing on high-contrast edges, and it's exaggerated with the teleconverter:
Incidentally in the background there's a car ferry. Venice's main island doesn't have cars, but the Lido that shields Venice from the sea is large enough to have roads and buses. If the residents of the Lido want to visit the rest of the Italy by car they have to take a ferry across the lagoon. Venice is massively awkward and weird and yet people go there, so it's a paradox.
Again, I have no idea who these people are.
Also incidentally telephoto and super-telephoto lenses are good for panoramas. You have to take lots of images to get any kind of coverage, but on the positive side the combination of consistent across-the-frame image quality, low vignetting when stopped down, low distortion, and flat perspective lend themselves to stitching images together. Just for the sake of heck I tried to capture an ocean liner off in the distance with three shots side-by-side:
You can see one of the joins in the left side of the main dome. I could have fixed it, but I didn't. Why? Nothing has a reason. It's all arbitrary.
Imagine being a waterbus driver in Venice. It requires a certain amount of skill, a certain amount of brute force, you can wear sunglasses, the scenery is nice, albeit that you probably aren't paid enough to live in Venice, so you have to get up at 05:00 every day and commute, and eventually all of the waterbuses will be automated, at which point you'll become an unemployed fat drunk, and then you'll die in an overcrowded slum far away from Venice.
But the same is true of everyone. We are a race of microscopic bugs that grow and thrive in a small puddle of water, but the puddle is slowly evaporating, and one day all of the puddles will be gone. The best we can hope for is to die before the end. What about f/6.3 or f/8 or the other apertures? I shot a few images stopped-down but the results were almost indistinguishable from wide open, and I couldn't be sure if the differences were because of the teleconverter or a shaky lens or slight differences in focus. Ultimately I conclude that with a 300mm f/4 IS the Canon 1.4x MkII extender is essentially transparent, e.g. it degrades the corners slightly but otherwise makes the image no worse, and you can shoot wide open without wasting your time.
