Posted: 12/6/2008 6:28:20 AM EDT
| If I choose to go with the Canon XSI what do I need to look out for when choosing a lens to make sure that it will be compatible with any future upgrade as far as body is concerned? thanks |
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It's hard to say without knowing what you plan to upgrade to in the future. There are two categories of lenses that fit the Rebel and xxD series cameras. EF and EF-S. The cameras with larger sensors like the 5D and the 1D series cannot use the EF-S lenses. The third party companies like Sigma and Tamron also make lenses that fit these two categories but I don't recall how they identify them.
If you plan to upgrade to one of those larger sensor cameras then you should avoid buying EF-S lenses. Having said that, it would be stupid to avoid buying a lens you need at this moment because you think you might buy a camera at some point in the future that may or may not be compatible with that lens. Lenses generally hold their value better than bodies. So long as you don'y get ripped off when you buy the lens in the first place you should be able to sell it without taking too much of a loss. |
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Could someone explain the difference between the two? The ef-s lens is designed to be true focal length for the smaller sensor cameras. You don't have to figure in the correction factor. Ef-s lenses will not fit on my older film cameras. That is to say, the EF-S lenses will not work on the Canon 5D (full frame) or 1D (1.3x crop factor) series cameras. EF-S lenses will only work with the 1.6x crop factor bodies. (rebel, 20D, 30D, 40D, 50D... If you have a EF-S set of lenses and decide you want a 1D or 5D camera, you will have to get EF lenses too. -Mark. |
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Could someone explain the difference between the two? The ef-s lens is designed to be true focal length for the smaller sensor cameras. You don't have to figure in the correction factor. Ef-s lenses will not fit on my older film cameras. Actually that's incorrect. An 18mm EF-S lens will give the same (or nearly the same) resulting field of view as an 18mm EF lens (when used on a cropped sensor body). On the other hand, the difference on a full frame body will be HUGE... since the EF-S lens won't fit on the FF body. 
For canon, the smaller sensors don't capture the full size of the image as what a 35mm film/full frame digital sensor does. Thus when you take a picture with a "crop sensor" camera, such as a drebel, 20/30/40/50D, or whatever other new cameras they come out with in the future, you need to multiply the focal length by 1.6x to compare to what focal length you would be using on a full frame (or film) camera to get the same view. A 100mm lens on a 40D will be very similar* to a 160mm lens on a film camera. Essentially you get a "free" zoom when you buy the crop sensor cameras. But at the same time you can't zoom out as wide, so you "lose" the wide angle end of things. The difference between the EF and EF-S lenses is that the EF-S lenses don't have as large of an image circle... that is, the image hitting the sensor (or film) is only wide enough to cover the smaller sensors, but would show horrible light falloff in the corners/edges if you managed to attach them to a FF camera. * But not exact! Your depth of field is larger on a cropped sensor camera, due to the fact that you end up shooting with a shorter focal length lens. The same is true when using the same lens on different bodies, and "zooming with your feet" to get the same subject size... since you will be standing farther back from your subject with a cropped sensor camera, your depth of field will be larger. |
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Could someone explain the difference between the two?
The ef-s lens is designed to be true focal length for the smaller sensor cameras. You don't have to figure in the correction factor. No. As was already stated, the focal length is always the focal length. Having said that, the EF-S lenses are generally esigned to provide similar to fields of view to the full frame EF lenses. The 2 best ef-s lenses are the 10-22 and the 17-55, which give a very similar field of view to the 16-35 and 24-70 which are two of the most popular lenses for full frame cameras. As for the purpose of EF-S lenses: When you use a normal lens with a camera that uses a smaller sensor the edges of the image provided by the lens is "wasted". By only providing an image the size of the smaller sensor the EF-S (smaller exit pupil, in rifle scope terms) lenses are able to provide a smaller, lighter and less expensive piece of hardware that gives nominally the same quality as the EF lenses. |