43
votes
Accepted
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 ...
- 173k
32
votes
Accepted
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 ...
- 38k
28
votes
Accepted
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 ...
- 31.7k
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 ...
- 4,016
23
votes
How do zoom lenses restrict their widest aperture at the telephoto end?
The entrance pupil is limited by the diameter of the front element, and that is what usually restricts the maximum aperture of telephoto zoom lenses - not the physical size of the aperture diaphragm.
...
- 173k
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...
- 843
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 ...
- 38k
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 ...
- 38k
21
votes
Accepted
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 ...
- 1,864
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 ...
- 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.
...
- 22.1k
17
votes
How is actual focal length greater than focal range of lens?
When the engineers are designing a lens, the 70-300 is a target focal range they design to, but it's not important that they hit it exactly as long as it covers the advertised range. As they tweak the ...
- 1,192
16
votes
Accepted
What prevents a f/1.8, 24 mm - 70 mm or similar range zoom lens from being made?
It's most likely a commercial decision based upon cost and performance.
Let's take your prime at f/1.2 example.
Canon makes a number of 50mm lenses.
The EF 50mm f/1.8 II is about $100. It has 6 ...
- 50.7k
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 ...
- 12.8k
15
votes
Accepted
What is the relationship between focal length and minimum focus distance?
It depends entirely on how the lens was designed, there is no general formula or way of determining the minimum focus distance. Lenses of the same focal length can have completely different minimum ...
- 119k
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 ...
- 1,452
15
votes
Accepted
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....
- 20.5k
14
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) ...
- 241
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/...
- 173k
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 ...
- 173k
13
votes
Accepted
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 ...
- 31.6k
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.
- 19k
13
votes
Accepted
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 ...
- 31.7k
12
votes
Accepted
What focal length is used in photos where the model is zoomed in but the background appears open and wide?
Using some reasonable assumptions, geometry, and a bit of math, we can put actual constraints on the composition.
Measure the height of the trailer door as a percentage of the total height of the ...
- 31.7k
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 ...
- 6,385
12
votes
Accepted
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 ...
- 173k
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 ...
- 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 ...
- 31.7k
11
votes
What software can show my most frequently used focal length?
Assuming that:
The focal length has been recorded in the file metadata
You are running a Unix-like OS such as Linux or OS X (or Cygwin in Windows)
You have installed the exif command line tool
Run ...
- 243
11
votes
Accepted
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'...
- 102k
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