July 22nd, 2010
DSLR Lenses on the Cheap
Just because you have a fancy new DSLR, it doesn’t mean you are limited to fancy new DSLR lenses. In the olden days, all you had to worry about was whether a lens would fit your camera. Now you need to worry about crop factors and autofocus, too. But the reality is that pretty much any lens that will fit onto your camera will work. There will be some limits, but some of them are actually useful.
The crop factor, for instance, can work to your advantage. If you shoot wildlife the 1.5x focal length multiplier will turn a 400mm lens into a 600mm lens. Conversely, a lens made for a DX format camera will become ultra-wide on a regular film of full-frame digital SLR, although generally the quality of these lenses isn’t so good and you’ll probably get some vignetting at the corners where the larger sensor “sees” the edges of the lens.
But the point is that, if you are willing to make some compromises, you can buy some amazing, top-quality lenses for very little money. So instead of picking up that third party, vibration reduction auto-everything lens, take a trip to your camera store and see what is on offer on the second-hand case.
To keep it easy, I’m using a lens I picked up recently. It’s a Nikon 24mm ƒ2.8 AF-D, released in 1993, and I’m using it on a Nikon D60, an SLR with a DX sized sensor. This means the lens gives a 35mm equivalent of 35 mm.
Why buy a full-frame lens for a DSLR? First, Nikon doesn’t make a prime (fixed focal length) 35mm equivalent for digital cameras. In fact, the only prime DX lens is a 10.5 mm fisheye. Second, although ƒ2.8 isn’t a particularly fast maximum aperture, it lets in a lot more light than a zoom lens and is a lot better at throwing the background out of focus (wide aperture equals shallow depth of field.)
Third, prime lenses often give sharper results and are smaller and lighter than zooms. Finally, when I eventually spring for a full-frame DSLR (the D700 is looking mighty tempting), I won’t have to sell the lens.
So, I have a tack sharp lens which works at 35mm, the favorite focal length of candid shooters and street photographers (the most popular Leica lens is a 35mm prime). But what are the problems?
First, and probably the scariest for photographers who have grown up with digital, is the lack of autofocus. The lens was designed 15 years ago, before Nikon put motors in its lenses. Old film bodies and the higher-end DSLR bodies have motors inside which will focus these older lenses. The D60 doesn’t.
This means manual focussing, which is to be honest a little tricky these days. Older cameras had focussing screens with a split-image aid on them — line up the two halves and you were ready to go. Plus, older manual focus lenses had a much longer “throw” and a stiffer focussing ring which made accurate hand-focussing a lot easier. The D60 has an LED rangefinder in the viewfinder which tells you when you have got the subject sharp, but it’s not ideal.
Thankfully, the lens is wide enough to allow some cheating. Taking advantage of a big depth of field, you can stop the lens down to ƒ8 and use what is called the hyperfocal distance. In practical terms, if I set the focus to 4’11”, everything from three and a half feet to infinity will be sharp. This means you can wander the streets and snap away, confident that almost everything will be in focus.
Another advantage of these older leses is that they were made before the camera did everything for you and therefore have some handy extra markings:
Below the focus scale you see the depth of field markings. Say the lens is set at ƒ22. Just move the “infinity” mark to line up with the number 22 on the left and everything from there to the 22 mark on the right will be acceptably sharp.
You also see a white dot just between 11 and the focus mark. This is for infrared photography. Infrared light has a different wavelength and will not focus where visible light does. What you do is to focus normally and then twist the barrel to line the distance up with this dot instead of the central marker. It’s pretty useless with digicams as they have built-in filters to cut out the infrared light. It’s nice to know what it does, though.
There is also a manual aperture ring. Sadly, this can’t be used, and you need to lock the dial to ƒ22 for the camera to function. It’s a shame, as this is a quick and easy way to set the aperture size.
If you are used to using your camera’s auto exposure settings, especially the flash modes, some older lenses will limit them. This is because they don’t offer all the depth information needed for the camera’s calculations. But then, with a digicam, you can always take a test shot and tweak the settings.
Try it. Not only will you be able to get a very nice lens for little money, the limitations will be both fun and informative: you’ll learn a lot about photography just by having to do a few things for yourself. It’s like having somebody to tie your shoelaces for you. It’s great when they’re around, but isn’t it better to know how to do it yourself?
***
