Q. what's the difference between an optical zoom and a digital zoom on a camera? is it okay to have a digital zoom but not an optical zoom? what are they?
Answer
More and more camera manufacturers are choosing to label their digital cameras with the total (optical x digital) zoom. This is an unfortunate development and only serves to confuse consumers.
Most people who have used a 35mm camera or an APS camera are aware of only optical zoom. Optical zoom uses the optics
(lens) of the camera to bring the subject closer. Digital zoom is an invention of digital video cameras. It is not uncommon to see digital videocams with 300x digital zoom.
For our purpose, digital zoom is not really zoom, in the strictest definition of the term. What digital zoom does is enlarge a portion of the image, thus 'simulating' optical zoom. In other words, the camera crops a portion of the image and then enlarges it back to size. In so doing, you lose image quality. If you've been regularly using digital zoom and wondered why your pictures did not look that great, now you know.
Is digital zoom therefore all bad? No, not at all. It's a feature that you might want in your digital camera (in fact, all digital cameras include some digital zoom, so you can't really avoid it), especially if you don't care about using (or don't know how to use) an image editing software. So, as far as digital zoom is concerned, you can do it in camera or you can do it afterwards in an image editing software. Any cropping and enlarging can be done in an image editing software, such as Photoshop.
So, when a digital camera is advertised with 3x digital zoom, no big deal. You can achieve the same 3x (and in fact as much as you want) digital zoom effect in an image editing software. The advantage of doing it later is that you can then decide exactly which portion to crop and how much to enlarge (3x, 4x, ...). If you do it in camera, image quality is irreversibly lost.
Someone in a digital camera forum once mentioned that he uses digital zoom because it might mean the difference between capturing a great shot or not at all. Umm, let's think about this a bit. True, if by zooming digitally in camera you get to see what your subject is doing and thus can capture the shot at the right moment. Not quite true, if it's something like a landscape shot, and the mountains ain't going nowhere fast, because you can achieve the same cropping and enlarging effect after the fact in your image editing software. So, it's really up to you, if you know what you're doing.
What, therefore is the rule of thumb, when it comes to using zoom? Here it is: Always use optical zoom. When buying a camera, choose one that warns you that you are about to use digital zoom or that allows you to disable digital zoom (most do). If you do use digital zoom, use it only if it does not appreciably impact your image quality. If you rarely print past 4x6 in. photos, digital zoom may not adversely affect you.
When comparing cameras, you should always use optical zoom. There is no point in comparing digital zoom with digital zoom or optical zoom with total zoom. Always compare optical zoom with optical zoom.
All in all, optical zoom is much better. Digital zoom is just like zooming in on it on your computer. If it has no optical zoom, don't buy it.
More and more camera manufacturers are choosing to label their digital cameras with the total (optical x digital) zoom. This is an unfortunate development and only serves to confuse consumers.
Most people who have used a 35mm camera or an APS camera are aware of only optical zoom. Optical zoom uses the optics
(lens) of the camera to bring the subject closer. Digital zoom is an invention of digital video cameras. It is not uncommon to see digital videocams with 300x digital zoom.
For our purpose, digital zoom is not really zoom, in the strictest definition of the term. What digital zoom does is enlarge a portion of the image, thus 'simulating' optical zoom. In other words, the camera crops a portion of the image and then enlarges it back to size. In so doing, you lose image quality. If you've been regularly using digital zoom and wondered why your pictures did not look that great, now you know.
Is digital zoom therefore all bad? No, not at all. It's a feature that you might want in your digital camera (in fact, all digital cameras include some digital zoom, so you can't really avoid it), especially if you don't care about using (or don't know how to use) an image editing software. So, as far as digital zoom is concerned, you can do it in camera or you can do it afterwards in an image editing software. Any cropping and enlarging can be done in an image editing software, such as Photoshop.
So, when a digital camera is advertised with 3x digital zoom, no big deal. You can achieve the same 3x (and in fact as much as you want) digital zoom effect in an image editing software. The advantage of doing it later is that you can then decide exactly which portion to crop and how much to enlarge (3x, 4x, ...). If you do it in camera, image quality is irreversibly lost.
Someone in a digital camera forum once mentioned that he uses digital zoom because it might mean the difference between capturing a great shot or not at all. Umm, let's think about this a bit. True, if by zooming digitally in camera you get to see what your subject is doing and thus can capture the shot at the right moment. Not quite true, if it's something like a landscape shot, and the mountains ain't going nowhere fast, because you can achieve the same cropping and enlarging effect after the fact in your image editing software. So, it's really up to you, if you know what you're doing.
What, therefore is the rule of thumb, when it comes to using zoom? Here it is: Always use optical zoom. When buying a camera, choose one that warns you that you are about to use digital zoom or that allows you to disable digital zoom (most do). If you do use digital zoom, use it only if it does not appreciably impact your image quality. If you rarely print past 4x6 in. photos, digital zoom may not adversely affect you.
When comparing cameras, you should always use optical zoom. There is no point in comparing digital zoom with digital zoom or optical zoom with total zoom. Always compare optical zoom with optical zoom.
All in all, optical zoom is much better. Digital zoom is just like zooming in on it on your computer. If it has no optical zoom, don't buy it.
how do you read a lens?
coy5coy
1.
Canon EF-S 17-85MM f4-5.6 IS USM Standard Zoom Lens
can someone please break this down so I can understand how to read this please?
2.
Canon EF-S 17-85MM f4-5.6 IS USM Standard Zoom
Canon EF 70-300mm f/4.5-5.6 DO IS USM Telephoto Zoom Lens
why would anyone want a zoom lens that stops at 85MM, isnt the larger the number better the zoom? Wouldnt the 300mm be much better because it zooms in better?
Answer
Canon is the manufacturer of the lens, meaning that the lens will mount onto a Canon body.
The focal length (e.g., "70-300mm) is the field of view that the lens can see. A "Normal" focal length is about 35mm on a consumer Canon DSLR and 50mm on a 35mm SLR. This gives roughly the perspective that we, as people, see. A wider lens can see more of a scene (think really big landscapes), but the perspective is exaggerated and as something gets close to the camera is starts to appear much larger. An example of this is the classic image of a dog poking it's nose towards camera; the nose will look really big while the rest of the dog is small because it's further back. A telephoto lens makes a distant scene look bigger (smaller field of view) and also flattens the picture. Think of a telephoto lens as being like a pair of binoculars and a wide angle lens as being those binoculars turned around backward.
EF stands for "ElectroFocus." This means that it is autofocus and will mount on an EOS camera (Any DSLR, recent 35mm SLR's too). An acronym of EF-S means that the lens will only work on cropped-sensor (aka, APS-C) DSLR's such as the Rebel series (or 300D/350D/400D/450D/1000D) and 10D/20D/30D/40D series. It will mount on any EOS camera, but light will not hit the corners of the image sensor or film on a non-cropped camera, and this will result in a big black circle near the edges of the image.
IS stands for image stabilization. This means that there are mechanisms in the lens that helps reduce the shake caused by hand holding it, which in turn makes it easier to shoot sharp images in low light situations.
USM is an UltraSonic Motor. A USM mechanism is virtually silent, and generally focuses much faster than non-USM glass.
DO means "Diffractive Optics" in Canon jargon, and DO lenses can be identified as having a green ring around the lens body towards the front of the lens. Diffractive Optics is a technology that allows very sharp lenses with virtually no chromatic aberration. These lenses are normally a bit smaller than one would expect for their focal length/speed as DO is used to reduce the need for huge pieces of glass, but these lenses are also very expensive. I've never heard of a bad DO lens.
Zoom, of course, means that the lens can change it's focal length -- zoom in and out. Zooms have generally lower image quality than a comparable fixed or prime lens, that does not zoom. A bigger zoom range does not imply better. As lenses are made to zoom more, they lose image quality because you're trying to make the same glass work for a wide range of focal lengths. Basically, you're making the glass perform at an okay level for any given focal length, but never excel at any given one either. A fixed/prime lens will usually give the best optical quality. After that, a small zoom range (16-30mm) will give the next best quality, then a medium zoom range (18-55mm), and a large zoom range (18-200mm or 70-300mm) will give the least optical quality. This is just a general guideline of course, optical quality varies significantly from lens to lens. The 17-85mm IS lens will be a better option if you had to choose just one lens right now, as it covers the "Normal" range, which is where the majority of your shots will come from. The 70-300 DO is an amazing lens, and would be a great second lens.
The f/# is the maximum aperture of the lens. A smaller number is generally better, as the lens can perform in lower-light situations and can also "Sweet spot" (get to it's best working conditions) at a lower aperture as well. A bigger aperture (lower number) means that there is a bigger hole for light to pass through in the lens, which means more light reaches the sensor in a given time, and thus the sensor can record the image faster than with a lens at a lower f/#.
Canon is the manufacturer of the lens, meaning that the lens will mount onto a Canon body.
The focal length (e.g., "70-300mm) is the field of view that the lens can see. A "Normal" focal length is about 35mm on a consumer Canon DSLR and 50mm on a 35mm SLR. This gives roughly the perspective that we, as people, see. A wider lens can see more of a scene (think really big landscapes), but the perspective is exaggerated and as something gets close to the camera is starts to appear much larger. An example of this is the classic image of a dog poking it's nose towards camera; the nose will look really big while the rest of the dog is small because it's further back. A telephoto lens makes a distant scene look bigger (smaller field of view) and also flattens the picture. Think of a telephoto lens as being like a pair of binoculars and a wide angle lens as being those binoculars turned around backward.
EF stands for "ElectroFocus." This means that it is autofocus and will mount on an EOS camera (Any DSLR, recent 35mm SLR's too). An acronym of EF-S means that the lens will only work on cropped-sensor (aka, APS-C) DSLR's such as the Rebel series (or 300D/350D/400D/450D/1000D) and 10D/20D/30D/40D series. It will mount on any EOS camera, but light will not hit the corners of the image sensor or film on a non-cropped camera, and this will result in a big black circle near the edges of the image.
IS stands for image stabilization. This means that there are mechanisms in the lens that helps reduce the shake caused by hand holding it, which in turn makes it easier to shoot sharp images in low light situations.
USM is an UltraSonic Motor. A USM mechanism is virtually silent, and generally focuses much faster than non-USM glass.
DO means "Diffractive Optics" in Canon jargon, and DO lenses can be identified as having a green ring around the lens body towards the front of the lens. Diffractive Optics is a technology that allows very sharp lenses with virtually no chromatic aberration. These lenses are normally a bit smaller than one would expect for their focal length/speed as DO is used to reduce the need for huge pieces of glass, but these lenses are also very expensive. I've never heard of a bad DO lens.
Zoom, of course, means that the lens can change it's focal length -- zoom in and out. Zooms have generally lower image quality than a comparable fixed or prime lens, that does not zoom. A bigger zoom range does not imply better. As lenses are made to zoom more, they lose image quality because you're trying to make the same glass work for a wide range of focal lengths. Basically, you're making the glass perform at an okay level for any given focal length, but never excel at any given one either. A fixed/prime lens will usually give the best optical quality. After that, a small zoom range (16-30mm) will give the next best quality, then a medium zoom range (18-55mm), and a large zoom range (18-200mm or 70-300mm) will give the least optical quality. This is just a general guideline of course, optical quality varies significantly from lens to lens. The 17-85mm IS lens will be a better option if you had to choose just one lens right now, as it covers the "Normal" range, which is where the majority of your shots will come from. The 70-300 DO is an amazing lens, and would be a great second lens.
The f/# is the maximum aperture of the lens. A smaller number is generally better, as the lens can perform in lower-light situations and can also "Sweet spot" (get to it's best working conditions) at a lower aperture as well. A bigger aperture (lower number) means that there is a bigger hole for light to pass through in the lens, which means more light reaches the sensor in a given time, and thus the sensor can record the image faster than with a lens at a lower f/#.
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