Last week I added another lens to the arsenal, in the form of a Canon 'L Series' 17-40mm Ultra-Wide. This is my second 'L' purchase, following the 24-105mm lens that came with my Canon 5D MK2 body (Full frame upgrade). For anyone who is unfamiliar with L-Series, these are the 'Luxury' lenses in the Canon EF family line, and what a difference the results are, compared to the EF-S series that I was using alongside the now departed Canon 7D crop body. Naturally, the L-Series glass comes at a price, but they're worth every penny. So, what is the difference between EF (L-Series) and EF-S lenses, you may ask...EF-S lenses are specifically designed for APS-C digital bodies and optimised for the fact that they have smaller sensor and mirror. EF-S lenses are marked with a white dot on the mount instead of red one that EF-glass has, and can be only used on EF-S compatible bodies (almost all of smaller-sensor Canon DSLRs, up to EOS 7D). Film and larger-sensor digital cameras (5D, 1D, 1Ds) take only EF lenses. If you have a camera with EF-S mount support (such as EOS 7D, 50D or 500D), you can use both EF and EF-S lenses. EF-S lenses are a slightly different format whereby the rear element sits closer to the lens, this is possible due to the smaller mirror with APS-C sensor. The distance from the back of the lens to the image plane is known as the back-focus distance, hence the S in EF-S standing for short back focus. Other manufacturers have lenses designed for smaller sensors with appropriately smaller image circles but they don't have a different back focus distance. Having the lens sit slightly closer does make it slightly easier to design wide angle lenses, however I've heard the reason Canon introduced EF-S lenses was so they could scale down existing lens designs as a base for the optical design to avoid having to start from scratch. It's often said you can't use EF-S lenses on a full frame body (such as the 5D, 1Ds) but this is not strictly true. Canon use a different shaped rear baffle to physically prevent you mounting as the mirror could hit the lens and cause damage. However this can be removed to allow mounting, and since the rear element moves when zooming there are positions that allow shooting. Vignetting is a problem as EF-S lenses project a smaller image circle, but again the image circle can get bigger while zooming so some focal lengths work ok.
EF (L-Series) is Canon's professional line (though used extensively by non-professionals) of EOS EF auto focus 35mm SLR and DSLR still camera lenses. Some say L stands for "Low Dispersion" - achieved by the UD lens elements found in these lenses. But, the true answer is probably the one in Canon's Lens Work III Book - "L" is for "Luxury". Watch the sidelines at the next professional sporting event you attend or watch on TV. Look for the identifying L-lens red stripe around the end of the photographers' camera lenses. These are the people who make a living with their equipment - and they frequently trust the Canon L Lens Series for their income. About their L lenses, Canon says "these lenses use special optical technologies [such as] Ultra-low Dispersion UD glass, Super Low Dispersion glass, Fluorite elements, and Aspherical elements to push the optical envelope."
OK so what does that mean - practically speaking? What you can get when you use Canon L lenses (if you do your part right) are amazing pictures. In fact, this amazement is said to cause a disease know as "L-Disease". Once caught, it is incurable.
After upgrading to the full frame 5D MK2 with 24-105MM lens, I couldn't wait to get started. If you trace back my blog entries you'll find many photographs that I've taken with my new kit. To the viewer there may seem little difference between the photographs on my blog from each camera, but there is a noticeable difference between the prints, especially at A2 (25x17 inches). Obviously, when you factor in the full-frame side of things, the upgrade has been a master stroke in my opinion, as it has opened up more capability, mainly the ability to get that much more subject onto a full frame sensor. As for my two lenses - the 24-105mm is my everyday 'Walk around' lens, which covers most aspects of my photography needs, whereas it doesn't quite cut the mustard up close, hence the need to go wider in that pursuit. That's where the 17-40mm glass makes an appearance. A popular misconception with some photographers is that Wide Angle lenses are to 'Get it all in'. I tend to disagree. Ultra-wide's are for getting yourself, and therefore the viewer, right smack into the middle of something. If you can't or won't get close, leave the Ultra-wide at home. These lenses have the ability to rub the viewer's nose in your subject. Properly used, Ultra-wide's grab your viewer and yank him into the middle of your situation, bringing the viewer into the photo, not for fitting a subject into a photo. Ultra-wide's require you to get very close and personal to anything you are shooting. Even a fraction of an inch (or cm) will make a massive difference in your composition, so you need to be very deliberate with your movement. If you use them properly, you should be rewarded with dynamic images. I find that regardless of which lens I use, and however many photos I make on a trip, the ones I like the most are always those made with a wide angle lens. My old 10-22mm Wide was a brilliant lens and gave me the experience I now carry forward. As the weather up North has been sh1te recently, I haven't had a decent chance to road test my new 17-40mm Wide, but rest assured it will put through its paces soon enough. Until then I'll twiddle my thumbs and plan my next outing. Lots of printing/framing to get through, which is ideal when the weather is poor. Indoors all the way, but not for long. Until then...
Ash
