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June 19, 2008
[ BACK TO THE FUTURE ]
REMEMBER THE GOOD OLD DAYS (cue violins) when you bought your first single lens reflex 35mm camera? Remember how it came from the box with one lens already attached – a fixed focal length 50mm affair, with a maximum aperture of somewhere between f2.8 and f1.4?
In those days zooming was done by foot, move in for a close-up, go wide by stepping back. And focussing was done with a smoothly damped ring around the lens with a good grip for the fingers.
We were reminded of the olden days when we went snapping with the Olympus E-420 (see today’s review) fitted with a 25mm f2.8 lens (RRP $350). This little tacker is really small – a mere 23mm protruding from the camera body. It is pin sharp and free of distortion. It reminded us of how good a simple prime lens can be.
The thing is that a 25mm lens on a camera with a Four Thirds sensor has the same field of view (FOV) as a 50mm lens on a 35mm film camera, so it is truly analogous to the kit lens of the past. F2.8 is a modest aperture for such a lens, so it can be kept small.
According to Wikipedia (tinyurl.com/yd4h7m) the “normal” lens is that which produces images that look natural to the human eye. Oscar Barnack, the Leica creator, settled on 50mm as the focal length that produced the best compromise between sharpness and the natural perspective when used with 35mm film.
Canon ($150) and Nikon ($235) have 50mm f1.8 lenses in their catalogues which are the least expensive lenses they make. Even though these do not have the same FOV as a 50mm lens on a film camera they seemed worth a try. Because the DSLR sensors are smaller than a 35mm film frame there is a multiplier factor that must be applied to calculate their FOV in film terms. The Nikkor 50mm behaves like a 75mm on a digital camera and the Canon looks like an 80mm. To get the equivalent FOV of a 50mm lens we would need to use a 35mm optic, but they are not cheap for either camera.
It turns out that using a 50mm lens on a DSLR is still a joy. The FOV of a slightly longer lens is better for portraits. And the advantages of the simple prime can still be enjoyed.
Anyone who has only used zoom lenses will be surprised at the sharpness of the prime. Generally speaking a cheap prime will have better contrast and colour than a zoom. And it is faster, which means that the viewfinder image is brighter. Very few people have zoom lenses with maximum apertures of f1.8, but such speed is par for a simple prime.
Prime lenses, unlike zooms, have virtually no distortion. Straight lines near the edge of the image will be straight, not bowed in or out. And they are compact and light because they are mechanically simple. Manual focussing is generally easier, although in this respect the Nikkor is the standout lens, better than the other two. Minimum focus distance is 45cm on both the Canon and Nikkor and a little closer on the Olympus, making them decent macro lenses.
Some change is not for the better. Zooms are convenient but primes are sweeter.
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Posted by terry at June 19, 2008 12:35 AM
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Comments
G'Day Terry,
You are dead right about the image quality of prime lenses over zoom lenses, particularly cheaper consumer zooms. However, the Field of view differential you refer to generally only applies to consumer DSLR cameras. The Canon EOS 5D and the Nikon D3 both have full 35mm film size sensors, which means that on these cameras 45-50mm lenses are standard, not short telephoto lenses. By the way have you had a chance to review the superb, medium-format H2D-39 Hasselblad digital camera yet?
Regards,
Bob
Posted by: Bob at June 19, 2008 06:07 AM
Love my 50mm f1.8 on my Nikon but I do wish I could get hold of a 35mm f2 at a reasonable price for the true 50mm focal length.
BTW you can obtain the 50mm f1.8 in Melbourne for under $170 now.
Posted by: RichardR at June 20, 2008 07:39 AM