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43 votes
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Is there a difference between taking a far shot on a 50mm lens and a close shot on a 35mm lens?

If you shoot from the same position with both lenses, then taking the 35mm lens and cropping it to the same angle of view of the 50mm lens will give you pretty much the same picture, other than the ...
Michael C's user avatar
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32 votes
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Why doesn't the picture become darker the more you zoom in?

The answer to this question revolves around explaining how zoom lenses function because you are correct in your observation: As you zoom to higher and higher magnifications the image dims unless ...
Alan Marcus's user avatar
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28 votes
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Do convex lenses make parallel light rays of different wavelength converge to different points?

Do convex lenses make parallel light rays of different wavelength converge to different points? Yes. The separation of different wavelengths of light is called dispersion. Different wavelengths of ...
scottbb's user avatar
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26 votes

Are lenses marked with the true focal length?

Oh, it is worse than that. Many lenses designed for still photography exhibit focus breathing, where the angle of view varies over the range of distances the lens can focus. Normally this isn't an ...
David Rouse's user avatar
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22 votes
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What is the shape of the focal plane?

The effect is called field curvature. A good discussion comes from Nikon. It is a lens aberration that can reduce the resolution of the lens when coupled with a flat sensor. In the old days, the ...
Ross Millikan's user avatar
22 votes

Is there a difference between taking a far shot on a 50mm lens and a close shot on a 35mm lens?

The proof is in the pudding – the focal lengths are not exactly the same as yours, but the differences are obvious...
Gnubie's user avatar
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22 votes

50mm mirror lens. Does one exist?

The mirror lens design resolves two key optical problems: All lenses suffer from chromatic aberration. This is color fringing due to the failure of the lens to refract (bend inward) all colors of ...
Alan Marcus's user avatar
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22 votes

Do convex lenses make parallel light rays of different wavelength converge to different points?

Light from a far distance object, like a star, arrive at the lens, as parallel rays. As they transverse the lens, they are forced to change their direction. They bend inward, we call this refraction ...
Alan Marcus's user avatar
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19 votes

Why is the background bigger and blurrier in one of these images?

The easiest way to think of this is with an image. When you use a wider lens, you have to be closer to your subject, which emphasizes the distance between the subject and background by making the ...
Cullub's user avatar
  • 500
19 votes

How does crop factor affect perspective?

When I started photography, this one took me ages to figure out, because people tend to explain it with a lot of math, or in a way that makes sense once you already grasp the principle but not before. ...
Tetsujin's user avatar
  • 23.3k
16 votes

Are lenses marked with the true focal length?

Published focal length is rounded in some degree, normally to nearest 5 or 10, or in some short cases, to the nearest 1. More precision would not be realistic, because the marked focal length is only ...
WayneF's user avatar
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15 votes

How can a lens with a single focal length focus on more than one plane?

First, focal length is a property of a lens (by lens I mean a piece of plastic or glass that's inside your camera's photographic lens system). If you just have a single lens (think magnifying glass) ...
naktinis's user avatar
  • 251
15 votes

Is there a difference between taking a far shot on a 50mm lens and a close shot on a 35mm lens?

Thanks to my schwifty skills in Inkscape, the rotation here is slightly off but the following shows exactly what you're comparing. These are the fields of view of a Nikon 35mm (inner) and a Nikon 50mm ...
Oli's user avatar
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15 votes
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Is this "tack sharp with blurred background" look done with Photoshop?

No photoshop necessary for that background. That's simply what happens when shooting a telephoto lens, f/2.8 or larger, and having the subject closer to the camera and much further from the background....
OnBreak.'s user avatar
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14 votes

Would a 50mm lens on a Canon APS-C crop produce the exact same image as an 80mm lens on a full frame camera?

Would these two photos be identical (i.e. depth of field, perspective etc.)? Depth of field: not exactly, but very similar if you also multiply the f-number used by the same crop factor. If you use f/...
Michael C's user avatar
  • 175k
13 votes

Shouldn't the diameter of the moon with a 600mm lens be double what it is with a 300mm lens?

Assuming both lenses are being used on the same size sensor, the area in the frame with a 600mm lens should be one quarter the area in the frame with a 300mm lens. The linear dimensions should change ...
Michael C's user avatar
  • 175k
13 votes
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Is a lense with an aperture larger than f/8 useful with an EOS 80 D?

So I have a EOS 80D and supposedly it has a max aperture of f/8. That's incorrect. The aperture is in the lens, not the body. All Canon EF and EF-S lenses, including the one that came with your ...
Caleb's user avatar
  • 31.7k
13 votes

What focal length do I need to get the same field of view as an iPhone SE?

According to this the iPhone SE has an 29mm-equivalent lens, so on a Fuji with a 23.6x15.6 sensor (Fuji XT-3)(crop factor 1.53) you need a 29/1.53=19mm lens for the same field of view.
xenoid's user avatar
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13 votes
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focal length and sensor width of a phone

The Redmi 6A uses the Sony Exmor IMX486 sensor, which is a 1/2.9" format sensor. Note that "1/2.9 inch" is merely a name, not its diagonal dimension (see: Why is a 1" sensor ...
scottbb's user avatar
  • 32.7k
12 votes

Longer Zoom Lens

The rule is learn to get closer. Really the best wildlife shots are made by people who have learned to get closer to wildlife ( a tricky skill ) and to wait ( find a spot you think they'll come near ...
StephenG - Help Ukraine's user avatar
12 votes
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does focal length change across an image?

There's really no such thing as a 'theoretically perfect' rectilinear lens with a perfectly flat field of focus and no geometric distortion. Even a lens that perfectly matches its blueprint would not ...
Michael C's user avatar
  • 175k
12 votes

Is focal length measured relative to the sensor or the lens?

Focal length is the distance from the conversion point to the image plane. The image plane could be film, or a digital sensor. For the purpose of understanding focal length, think of the lens as ...
Olin Lathrop's user avatar
  • 17.4k
12 votes

How to estimate pixels per degree for an image from a camera phone using EXIF data?

I assume this is a still frame from a video, because 16:9 is a common video ratio. In order to maintain constant frame size, "digital zooming" needs to be reinterpolated. Thus, yes, you need to ...
scottbb's user avatar
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11 votes
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Why would I need a portrait lens if I have a telephoto zoom lens covering the same focal length?

There is no such thing as a portrait lens. Just some are known to produce more appealing portraits. It can be used to shoot any other thing where the focal-length desired is the same. Note that I didn'...
Itai's user avatar
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11 votes
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Is it exactly true that doubling the focal length makes everything look twice as big?

Your intuition is right. To validate it, we can dig into basic high-school geometry. Although a camera lens is actually a complex lens made from many elements, conceptually and mathematically for ...
mattdm's user avatar
  • 143k
11 votes
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What does a pair of numbers in parentheses mean as a focal length value in metadata?

Values in Exif metadata can be stored as various data types, including ASCII text strings, "short" or "long" integers, or "rationals". A short integer is stored in two bytes; a long integer takes four ...
mattdm's user avatar
  • 143k
11 votes

How do I calculate the difference in lens reach between a superzoom compact and a DSLR zoom lens?

Assuming that the quoted 1365mm focal length is in 35mm full frame equivalent terms (because otherwise, it would be huge), then the actual focal length of the lens assembly is around 1365 / 5.6 ~= ...
twalberg's user avatar
  • 5,138
11 votes

How can I get more magnification when shooting wading birds?

Shooting from the same point of view will always result in the same image (in terms of magnification) with every 300mm lens you can get (zoom or prime doesnt matter). To achieve a higher magnification ...
Arji's user avatar
  • 1,633
11 votes
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Can I use a 127.5mm focal length on a crop camera to see what the view would be like using an 85mm full frame lens?

No. You should set your zoom to 85mm to see what an 85mm lens looks like on your camera. The focal length of a lens is a physical property that does not change no matter what size sensor you put ...
inkista's user avatar
  • 52.1k
10 votes
Accepted

Why do images sometimes look "softer" at higher focal lengths (like 300-500mm)?

Several focal-length-related factors can influence sharpness: It is usually harder to manufacture long focal lens, so at constant cost, expect a 50 mm to be sharp, a 200 mm to be not-so-sharp, and >...
Matthieu Moy's user avatar
  • 1,673

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