Alan's Blog




Super Telephoto Lens Cheap!

How would you like to buy a £12 000 super-telephoto lens for your camera for only £400?

I kid you not!

Even I don't have a great need for an 800 mm lens – and even less use for a lens with a focal length of close to 1300 mm so I certainly can't justify spending £12K on the Canon EF 800mm f5.6 L IS USM lens – and Canon don't make a 1300 mm lens (although, in years gone by, they did make an EF 1200 mm f5.6 L USM lens which weighed 36.37 lbs / 16.5 kg) and if they did it would be sold for some unimaginable figure.

However, all is not lost.

Many years ago, in the film camera era, I purchased a Mamiya 645J SLR camera with a wide range of lenses. I still have that camera and its range of lenses, from very wide angle 35 mm (equivalent to an approximate angle of view of a 21 mm lens on a 35 mm camera) right through to 300 mm. You have to remember that the 6 cm x 4.5 cm film size is about 2.6 times larger in area than 35 mm film size (36 mm x 24 mm). This is important. The 6 cm x 4.5 cm film format is a true format size, unlike the digital cameras bearing the '645' logo which have sensors way smaller than the measurement implies.

Now we come to the interesting part. If I used my 300 mm Mamiya 645 lens on my full-frame Canon camera it will give me an equivalent focal length close to 500 mm. The magnification factor between the two sizes is approximately 1.6x. This is because the image circle of the Mamiya lens is so much bigger than the full-frame Canon camera and therefore only the centre part of the image circle is used to illuminate the Canon sensor – and this is usually considered to be the part of the lens that produces the best image quality.

With that in mind, I recently bought a (second-hand) Mamiya 500 mm f5.6 lens for the 645 format (which, of course, fits my film camera perfectly) and an adaptor to permit me to fit it to my Canon camera. This gives me an equivalent focal length of 800 mm on my full-frame Canon camera and around 1300 mm on JP's APS-C camera sensor. I paid around £350 for the lens and £50 for the adaptor. £400 for an 800 mm f5.6 lens for my Canon – instead of paying £12 000. That's got to be a good deal. I might add that on the Micro-Four-Thirds sensor size of my video camera it will be the equivalent to a focal length of 1600 mm. Sturdy tripod needed! Of course, the cheaper lens set-up has no image stabilisation and no auto-focus – and the aperture has to be set manually – but why would I want to pay an additional £11 600 for those facilities? I have a rock-solid tripod and I can easily focus manually and set the aperture – no problem. The weight of the Canon 800 mm lens is 4.5 kg (approx. 10 lbs) which is almost double the weight of my Mamiya lens.

There are some super lenses out there on the second-hand market that cost a fraction of their new price and a fraction of the price you might need to pay for your digital camera lens. Many of these lenses can be adapted to fit your digital camera and, although designed for film, will work more than adequately on your digital camera. They won't give exactly the same results as a lens designed for digital cameras as they are designed with film characteristics in mind.

Lenses designed specifically for digital sensors direct the rays of light onto the sensor at as close to 90 degrees to the sensor as possible – i.e. perpendicular to the sensor. Film isn't as fussy as a digital sensor and the rays of light coming through the lens can hit the film from a much wider angle and still produce a good result. However, the difference in real world photography is minimal in practical terms. Also, the resolution of film isn't as high as modern digital sensors so the lenses may not be as 'tack' sharp. Again, this is unlikely to be noticeable in practical terms, particularly if you buy lenses that were designed for larger format film sizes where you will be using the centre portion of the lens's image circle.

Before you rush out and buy a range of lenses, do consider that many of your normal automatic functions won't work, which will slow you down when taking photographs (not necessarily a bad thing!). You have to make sure you can live with your purchase before you rush out and buy. I bought this 500 mm lens from the London Camera Exchange. They had two of them in stock at the time I bought mine. Don't all rush at once!

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