Sunday, 16 August 2015

Yongnuo Extender EF 2X III

Last month I went off to the Yeovilton Air Show, where I photographed the last Vulcan as it swooped and dived and climbed and banked and yawed and oscillated and rolled and tacked and eddied and wafted and roared and fluttered and flitted and flipped and flopped and wiggled through the air like a great green greasy greasel. The longest lens I own is a 70-200mm f/2.8 IS, which is fine as far as it goes - but 200m isn't really long enough for aeroplanes.

A Yongnuo 2X III, yesterday

There is a point when every man ponders the question of how to go longer than 200mm. Buy a good lens and put a teleconverter on it? Buy a crap lens, and put a teleconverter on it? Buy an old manual focus 300mm lens (and put a teleconverter on it)? Splash out on a 400mm f/2.8 that you'll never use, teleconverter? Buy one of those big long Sigmas?

Buy an APS-C camera and do lots of cropping? Buy an old manual focus 300mm lens and put it on a Micro Four Thirds body? Move closer to the subject? SELECT solution || ' and put a teleconverter on it' FROM options;

I call it "Lupita"

As I contemplated these options I cast my mind back to Roy Batty in Bladerunner, desperately pleading with the man who designed him, trading scientific-sounding gobbledegook about genetics in the hope of living for a few more years only to be told that his predicament was hopeless.

Some barriers cannot be surmounted with guile or trickery, you really have to spend a fortune or admit defeat or settle for second-best. Even billionaires are unsatisfied with their yachts, and when an ordinary man such as myself looks at his car or his wife he sees the Lamborghini Huracán he does not own, and also the pile of letters from Rachel Weisz' solicitor threatening legal action if he continues to hang around outside her house.

It won't fit a 50mm f/1.4, or any lens that has a protruding rear element. The extender comes with a compatibility chart which essentially lists all of Canon's posher telephoto primes and zooms from 135mm f/2 up.

Extenders also multiply the f-stop. The 135mm f/2 becomes a 270mm f/4, the 70-200mm f/4 becomes a 140-400mm f/8. Some of Canon's cameras have trouble autofocusing at this smaller aperture. On an APS-C camera the 70-200mm f/4 becomes a 224-640mm f/8 that might not autofocus any more.

The EXIF data recognises the 400mm focal length, but I'm not sure if the Yongnuo extender is transparent to the camera's electronic brain.

Yongnuo is based in Shenzhen, just across the border with Hong Kong. A long time ago neither you nor I would have heard of Yongnuo; the company's products would be imported by a made-up brand like Palinar or Rokinon or Hanimex or Prinz or whatever, but Yongnuo appears to be very confident and sells products under its own name via the internet. A few years back it made a splash with its manual flash guns, and recently it has branched out into lenses; copies of the old Canon 50mm f/1.8 and 35mm f/2, and the 2x extender that I'm writing about now. Or at least physical copies, the optical designs appear to be original.

Physically the extender resembles the modern Canon 2x III, fiscally it's half the price. It seems to be made out of tough plastic, although I'm not sure. It could be some kind of polycarbonate. The surface has a mild version of the speckled texture that Canon uses. The body doesn't rattle or creak and it's held together firmly with screws; there's a rubber weather gasket on the camera-facing end. The O in YONGNUO is made to look like aperture blades, so plus one for trying to establish a brand identity.

On a vintage 5D MkII. Handholding the stack is tricky but not too awkward - the extender doesn't weigh very much, the overall length is similar to a 400mm f/5.6 or the 100-400mm extended out a bit. If the oxygen tanks in the camera blow up my plan is to retreat into the lens, and then use its thrusters to put me on a trajectory back to Earth.

The serial number suggests that they haven't made very many. Mine is #479, the only other photographs I can find that show the serial number are on shopping sites in China and Poland, #223 and #396 respectively, so perhaps Yongnuo has only sold five hundred extenders. You could probably use this to work out how much money Yongnuo has made from selling them; you can work out a lot by studying serial numbers. The extender emerged at the beginning of 2015. It doesn't have an official UK importer. I can find very little about it on the internet so I was curious to see how it performed, in the middle, stopped-down. Airshows are all about centre sharpness stopped-down, because you're photographing aeroplanes outdoors in bright daylight.

Here's the difference between 200mm and 400mm, wide open:

The extender introduces a teeny-tiny amount of barrel distortion.

Now, I could spend hours of my life testing the extender at different focal lengths and apertures and distances and so on. Hours of my life that I should really spend boning up on SQLite. I bought a 2x extender so I could have 400mm, so for the purposes of this test I'm only looking at 400mm. What I want to know is whether the image quality at 400mm with an extender is better than simply doubling the size of a 200mm image with Photoshop.

So, in each of the following comparisons the image at the top was shot at 200mm and then doubled in size with Photoshop; the image at the bottom was shot at 400mm with the extender.

First, wide-open, f/2.8 at the top and f/5.6 at the bottom:

The 70-200mm f/2.8 IS is really good - the MkII version is apparently even better, but the original is no slouch - and even wide open at f/2.8 the image quality is great in the middle. You can see that the grain is larger but otherwise the extender is pointless at f/5.6. You get a tiny amount of extra detail but the image has a soft glow.

Now let's try f/5.6, f/5.6:

Which again doesn't make the extender look very good. But let's try stopping down a bit, to f/8, f/8:

That's more like it. The difference is slight, but at f/8 the extender does indeed deliver more detail, at the expense of some colour fringing. How about f/11?

Even better. At f/11 the extender justifies its existence. I'm utterly uninterested in the corners of the image at 400mm but just for the heck of it the extender improves from bland to average, here at f/5.6, f/8, and f/11:

On the off chance I happen to be photographing the Earth from space, and I need extreme corner sharpness, I would use a different lens (or ask the pilot to get a bit closer). Autofocus performance on a dull day seemed to be no slower or less accurate on my 5D MkII, although on my ancient infrared 10D it needed a nudge before it went all the way to infinity.

So, what did I learn from this? The extender turns my super 70-200mm f/2.8 into a decent 400mm f/8, for one-half the price of a Canon 2x Extender, or one-sixth the price of a 400mm f/5.6. But the proof of the pudding will be in the eating, and in this case the eating will be... pointing. It at some planes.