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by garik

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42

No, it does not have much use. Digital zoom is a restricted form of cropping: It is always done around the center. It is constrained to certain fixed increments. It is limited in quality by the firmware of the camera. On the other hand, cropping can: Be of arbitrary size. Be taken from any part of the image. Be processed using a variety of ...


40

The "times zoom" notation is simply the big number divided by the small one, so the examples you give are correct. "3x zoom" simply means the longest focal length is three times the shortest. This number really isn't very useful, though. On point and shoot cameras, it became popular because the starting focal length was generally about the same across all ...


26

There is no simple relationship between the physical length of the lens and its focal length. For example, a retrofocus wide angle is generally longer than its focal length, while a telephoto lens is shorter than its focal length. Inside a zoom, you have several lens groups that move independently. The focal length of the zoom depends on the relative ...


24

The biggest reason for difference in the two lenses is aperture. The 80-200mm is a constant f/2.8 throughout the focal range and the 18-200mm varies from f/3.5 to f/5.6, so substantially slower, especially at the far end. All this really means is that the 80-200 can let in more light at the same focal length over the other. Also, generally, zooms with ...


24

You are not required to purchase any lenses at all. It all depends on your photography needs and what you're willing to spend your money on. Regarding range, the superzoom 18-200 mm covers the same range as the other four lenses you mentioned. All of the other lenses focal ranges are parts of the large range of the 18-200 mm lens. The 18-200 can surely ...


23

These letters refers to zooming depth as follows, W = Wide angle T = Telephoto Read more about wideangle and telephoto in the tags.


20

A range of focal lengths indicates a zoom lens. There are two major classes of lenses. Primes, or primary lenses, have a single focal length. They tend to be higher quality, as there can be fewer lens elements, and fewer moving element groups. One exception to this rule is super telephoto prime lenses, particularly faster lenses (f/2.8), which are some of ...


19

Presumably because the people who buy their first DSLRs mostly come from the point-and-shoot world and care about the versatility afforded by the zoom more than about image quality. Also, a 50mm is way too long to be a good "default" lens with an APS-C camera, and good-quality ~30mm lenses are, due to certain quirks of optics, much more complex (and thus ...


18

I think an important advantage is saving time. When you happen to shoot hundreds of photos in a row stuck with a lens wider than would be optimal, cropping each one of the images into a smaller size in post processing would be quite tedious - usually you can't do that in batch unless you really don't care about resulting framing. Framing on spot, on the ...


18

The short answer is because it is cheaper to manufacture such lenses. The longer the lens and the wider the aperture, the larger the optical elements in the lens - thus larger the expense to produce them. A lens like 70-200/2.8 must have a front optical element of 200mm/2.8=72mm, which is quite a chunk of glass. On the other hand, the 70-300/4-5.6 needs to ...


18

At 50mm on your 18-55, the max aperture is f/5.6. On the 50mm f/1.8, the max aperture is - obviously - f/1.8. It is perhaps not immediately obvious, but f/1.8 lets in 10-12 times more light than f/5.6. That is the difference between shooting at 1/10 second shutter speed (which is absolutely a no-go for moving subjects) and shooting at 1/100 (which is a ...


17

I'll tackle this from the assumption you're looking for the best lens, money no object (as you indicate). The best lens will be the Canon 500L f4 IS, 600L f4 IS or 800L f5.6 IS mounted on a gimbal mount on a very solid tripod rated in the 20+lbs area. Which of these is the one for you comes down to a couple things. Focusing speed: The 800mm will have ...


17

Since your question is "What am I supposed to tell them?", I'm going to go a little bit off the literal math with my answer. What you should say is: The more "times-zoom" a lens has, the more compromise on image quality it has to have. Since my camera allows me to change lenses, I can have the flexibility of a huge zoom range without compromising on the ...


17

The focal length of a lens determines its field of view on your camera. If it has a long focal length, it has a narrow field of view, making the things in front of you appear large in the photograph. If it has a short focal length, it has a large field of view--it's a "wide angle" lens that takes in a large area, making objects appear small. A "zoom lens" ...


17

Technically 'Telephoto' means that the focal length [the mm] is longer than the lens is. In my experience, people in the photography world usually don't talk about it under that definition. Most of the time people say 'Telephoto' they just mean 'zoomed in' or in other words 'high mm' or 'long focal length' As has been mentioned, Nikon seems to say that 85mm ...


17

Same photo will result from using digital zoom or cropping. Advantage of digital zoom: you don't need a computer to crop it. You can upload straight to Facebook, print it out, etc. Cropping is a very common post-processing technique and this lets you do it easily, on the fly. Advantages of cropping after the fact: you can take more time to compose the crop ...


16

Focal length is a measure how the lens focusses the light into a point. When light enters a 50mm prime lens, the light converges into a point the camera sensor after 50mm. In addition the focal length determines the magnification of the object you photograph. A long lens (e.g. 300mm) magnifies the images a lot (useful for birding) while a short (wide angle) ...


16

As an owner and user of both the 450D and the EF 100-400mm, I can offer some help here. From a construction, durability, and handleability perspective, using the 100-400mm on the 450D will definitely not be a problem. Both the camera and the lens are durably built, and the lens mount can handle a considerable amount of rugged use and rough handling. The ...


16

If your camera only saves in JPEG, using digital zoom instead of cropping later avoids IQ loss from compressing twice. This is usually minor, but there it is.


16

Image quality. The wider the range of focal lengths on one lens, the more design compromises are made and the more correction must be applied deal with things like geometric distortion, chromatic aberration, and light fall off in the corners. Aperture. Even though the EF-S 18-200mm f/3.5-5.6 has the same maximum aperture of f/5.6 as the EF-S 55-250mm ...


15

Constant-Aperture Zoom Lens.


15

Provided you keep focus distance, ISO, aperture & shutter speed the same, and you zoom your 18-55mm lens to exactly the same focal length as the 50mm prime (which wont be exactly 50mm) then the images will very extremely similar when viewed as a whole. On closer inspection you will see differences in the level of distortion, sharpness, contrast and ...


15

A prime likely still has several advantages over a zoom at a given focal length. (Well, depending upon your needs and habits.) A less complex optical design. All else being equal, a less complex design is likely to have fewer compromises, which means the prime is more likely to have less distortion of any sort -- pincushion, barrel, coma, and chromatic ...


14

Nobody is saying that you must choose an 80-200 over an 18-200. An 80-200 (f/2.8) has some severe drawbacks compared to an 18-200, price, size and weight being among them besides the obviously limited zoom range. On the other hand, an 80-200 is far better behaved optically; it will tend to focus faster and more accurately (on a given camera body, and ...


14

Warning: this is yet another of my "book length" answers... :-) Let's start by a quick review of how a zoom lens works. Consider the simplest possible lens design -- a single element. One big problem with a single element lens is that the focal length of the lens determines the distance the element has to be from the film plane/sensor to bring a scene into ...


14

The W stands for Wide angle. The T stands for Telephoto. This has been asked around the web, for example here: Yahoo! Answers: What does W T button (zoom) stands for in zoom lens cameras? Tech-Recipes: Why are Camera Zoom Buttons Labelled W and T?


14

A greater zoom range means a more complex design at greatly increased cost. There are some excellent lenses make for broadcast with incredible zoom ranges, like the Fujinon 8-832mm (yes that's not a typo!), but you don't want to know the price. Designing a lens with a larger zoom range at a lower price does lead to compromises on quality. Finally lens ...



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