dslr camera lens terminology image
Hannah
Does mirrorless just mean NOT an SLR? Are all compact cameras mirrorless cameras? Is an EVIL camera just a little Friday night point-and-shoot digicam that you can stick big lenses on? Am I even using any of this terminology correctly? *sigh* So much to learn!
Answer
All of these terms are a bit vague.
EVIL means Electronic Viewfinder Interchangeable Lens
MILC means Mirrorless Interchangeable Lens Camera
And a newer term, Compact System Camera is also sometimes used.
Collectively these terms generally identify the cameras like the Sony NEX, Micro Four/Thirds cameras, and Nikon's 1 cameras. Generally anything between compact cameras and DSLRs.
I suppose that these cameras should be called bridge cameras, as that is in line with the original intent of the "bridge" idea. But the term bridge has been kidnapped by all of those low end run-of-the-mill compact cameras that have had huge zoom lenses slapped on the front of them.
There is some redundancy I suppose between the terms, as in the case of Nikon, the J1 does not have an electronic viewfinder, only a screen, so I suppose it would be a MILC. But then the Nikon V1 has an electronic viewfinder, so it could be a EVIL or a MILC.
And some micro Four/Thirds have an attachable electronic viewfinder, so are they MILC when the viewfinder is off, but a EVIL when the electronic viewfinder is attached?
And don't even get started with semi-transparent mirror cameras...
I suppose this is why the term "Compact System Cameras" is gaining popularity, as it is generic enough to be applicable to all of these cameras.
All of these terms are a bit vague.
EVIL means Electronic Viewfinder Interchangeable Lens
MILC means Mirrorless Interchangeable Lens Camera
And a newer term, Compact System Camera is also sometimes used.
Collectively these terms generally identify the cameras like the Sony NEX, Micro Four/Thirds cameras, and Nikon's 1 cameras. Generally anything between compact cameras and DSLRs.
I suppose that these cameras should be called bridge cameras, as that is in line with the original intent of the "bridge" idea. But the term bridge has been kidnapped by all of those low end run-of-the-mill compact cameras that have had huge zoom lenses slapped on the front of them.
There is some redundancy I suppose between the terms, as in the case of Nikon, the J1 does not have an electronic viewfinder, only a screen, so I suppose it would be a MILC. But then the Nikon V1 has an electronic viewfinder, so it could be a EVIL or a MILC.
And some micro Four/Thirds have an attachable electronic viewfinder, so are they MILC when the viewfinder is off, but a EVIL when the electronic viewfinder is attached?
And don't even get started with semi-transparent mirror cameras...
I suppose this is why the term "Compact System Cameras" is gaining popularity, as it is generic enough to be applicable to all of these cameras.
How do I work out the magnification of a zoom lens for a DSLR?
mouse_spin
I recently got a Canon EOS 400D digital SLR camera and I am looking to upgrade the lens for one with a more powerful zoom. However separate lenses are new to me so I am struggling to figure out which lenses are more powerful than others.
I was hoping someone would be able to tell me how you can either work out the strength of the optical zoom on Canon lenses, or give me suggestions of lenses to look at.
Any help is greatly appreciated.
Many thanks,
Martin.
Answer
You already have two excellent answers, but I have this one in the can at all times, so here you go. My answer adds a little visual aid.
There is not a lens-to-distance equation. If we are talking about a "35 mm equivalent," a 50 mm focal length is approximately "normal" view without any magnification. For most DSLR's, the lens factor of 1.5-1.6 means a "normal" focal length would be about 31-33 mm. If we go back to a 50 mm "normal" lens then, a 100 mm lens would be a "2 power" lens, 200 mm would be 4X, and so on.
Just divide the smaller number into the bigger number and you get the "X" power of the lens. For instance, a 35-80 mm lens is 2.3X zoom. Divide 80 by 35 and you'll get the result. 35-80 mm lens is 2.3X zoom. Divide 80 by 35 and you'll get the result.
It is usually better to know what the focal length of a lens in "35 mm equivalent" is and judge by that, rather than relying on the "X" power of the lens. For instance, most point and shoot cameras start at about 35 mm and have either a 3X or 4X zoom. This would make it a 35-105 or a 35-140. I've seen some that start at 28 mm, though. A 3X starting at 28 mm is 28-84 and a 4X is 28-112. Neither one is a particularly strong telephoto lens and the 4X is just about the same as the 3X that starts out at 35 mm.
It's also important to realize that tradition dictates that lens focal lengths are usually expressed in terms of "35 mm equivalent," where "35 mm" refers to a 35 mm film camera. This is because of the relation between the sensor size and the actual focal length of the lens and the resultant angle of view of the lens.
I have one point & shoot that is actually a 5.8-24 mm zoom. This is a 4X zoom. The 35 mm equivalent is 28-116 mm. The sensor is 7.2x5.3 mm. (1/1.8") (And I wish I knew someone who could explain how the heck they came up with sensor size terminology!)
I have another point & shoot that is actually a 5.7-17.1 mm zoom. This is a 3X zoom. The 35 mm equivalent is 34-102 mm. "How could a shorter focal length give a longer 35 mm equivalent?" you might ask. It's because the sensor is only about 5x4 mm. (1/2.5")
I have a few Nikon DSLR's and - thankfully - they all have the same size sensor. They all have a "lens factor" of 1.5. This means that you just multiply the actual focal length of the lens to get the 35 mm equivalent and then you can make comparisons accurately from camera-to-camera. Most Canon's, for instance, have a lens factor of 1.6. On a Nikon DSLR, a 28 mm lens is the "35 mm equivalent" of a 42 mm lens. On most Canon DSLR's, the same 28 mm lens is the equivalent of a 45 mm lens.
These example are just to show you how freaking confusing it can all become if you try to make sense of the "X" power of a zoom lens.
Bottom line...
Check the 35 mm equivalent specifications for the lens. This way, you will be leveling the field and comparing apples to apples. More or less.
Here is a mini-tutorial I made myself to compare focal lengths. This is NOT a lens test or a camera test! It is merely intended to show the difference between various focal lengths. The lens was the Nikon 18-200 VR lens, which is (by definition) an 11X lens, but that 11X does not tell you what the final image will look like. I added one more frame taken with a 300 mm lens. The camera was a Nikon D200 so there is a 1.5X "crop factor," "lens factor," or "focal length multiplier." There is further explanation on the image itself. It would help if you click on "All Sizes" above the image.
http://www.flickr.com/photos/7189769@N04/476181737/
This was done with two different lenses: the Nikon 17-55 and 70-300:
http://www.flickr.com/photos/samfeinstein/1245831147/
You already have two excellent answers, but I have this one in the can at all times, so here you go. My answer adds a little visual aid.
There is not a lens-to-distance equation. If we are talking about a "35 mm equivalent," a 50 mm focal length is approximately "normal" view without any magnification. For most DSLR's, the lens factor of 1.5-1.6 means a "normal" focal length would be about 31-33 mm. If we go back to a 50 mm "normal" lens then, a 100 mm lens would be a "2 power" lens, 200 mm would be 4X, and so on.
Just divide the smaller number into the bigger number and you get the "X" power of the lens. For instance, a 35-80 mm lens is 2.3X zoom. Divide 80 by 35 and you'll get the result. 35-80 mm lens is 2.3X zoom. Divide 80 by 35 and you'll get the result.
It is usually better to know what the focal length of a lens in "35 mm equivalent" is and judge by that, rather than relying on the "X" power of the lens. For instance, most point and shoot cameras start at about 35 mm and have either a 3X or 4X zoom. This would make it a 35-105 or a 35-140. I've seen some that start at 28 mm, though. A 3X starting at 28 mm is 28-84 and a 4X is 28-112. Neither one is a particularly strong telephoto lens and the 4X is just about the same as the 3X that starts out at 35 mm.
It's also important to realize that tradition dictates that lens focal lengths are usually expressed in terms of "35 mm equivalent," where "35 mm" refers to a 35 mm film camera. This is because of the relation between the sensor size and the actual focal length of the lens and the resultant angle of view of the lens.
I have one point & shoot that is actually a 5.8-24 mm zoom. This is a 4X zoom. The 35 mm equivalent is 28-116 mm. The sensor is 7.2x5.3 mm. (1/1.8") (And I wish I knew someone who could explain how the heck they came up with sensor size terminology!)
I have another point & shoot that is actually a 5.7-17.1 mm zoom. This is a 3X zoom. The 35 mm equivalent is 34-102 mm. "How could a shorter focal length give a longer 35 mm equivalent?" you might ask. It's because the sensor is only about 5x4 mm. (1/2.5")
I have a few Nikon DSLR's and - thankfully - they all have the same size sensor. They all have a "lens factor" of 1.5. This means that you just multiply the actual focal length of the lens to get the 35 mm equivalent and then you can make comparisons accurately from camera-to-camera. Most Canon's, for instance, have a lens factor of 1.6. On a Nikon DSLR, a 28 mm lens is the "35 mm equivalent" of a 42 mm lens. On most Canon DSLR's, the same 28 mm lens is the equivalent of a 45 mm lens.
These example are just to show you how freaking confusing it can all become if you try to make sense of the "X" power of a zoom lens.
Bottom line...
Check the 35 mm equivalent specifications for the lens. This way, you will be leveling the field and comparing apples to apples. More or less.
Here is a mini-tutorial I made myself to compare focal lengths. This is NOT a lens test or a camera test! It is merely intended to show the difference between various focal lengths. The lens was the Nikon 18-200 VR lens, which is (by definition) an 11X lens, but that 11X does not tell you what the final image will look like. I added one more frame taken with a 300 mm lens. The camera was a Nikon D200 so there is a 1.5X "crop factor," "lens factor," or "focal length multiplier." There is further explanation on the image itself. It would help if you click on "All Sizes" above the image.
http://www.flickr.com/photos/7189769@N04/476181737/
This was done with two different lenses: the Nikon 17-55 and 70-300:
http://www.flickr.com/photos/samfeinstein/1245831147/
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