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Optics is the science of light, and in photography often refers more specifically to to the properties and construction of lenses or the technical aspects of light sensors.

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4
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3answers
92 views

What determines whether chromatic aberration will be purple/green or red/cyan?

In my experience, both with my own photography and looking online, chromatic aberration is usually purple on one end and green on the other. However, I have also seen the same effect with red and ...
7
votes
4answers
1k views

Why is my large format lens so much smaller (in length) than my 35mm-format lens?

In general I have found that as the focal length of 35mm (or APS-C) lenses increases, the physical length of the lens increases as well. However, my large format lens is much thinner than other 35mm ...
0
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4answers
89 views

Aperture iris in front of lenses (in object space)

This question discusses the iris placed in camera body and this question does not reveal too much details about external iris. I recall from scattered information that I have read that iris placed in ...
19
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7answers
4k views

Can a smaller sensor's “crop factor” be used to calculate the exact increase in depth of field?

If APS-C and similar crop-sensor digital cameras have a focal length multiplying effect such that a 50mm lens has an apparent focal length closer to the field of view of an 80mm on a full frame ...
-1
votes
1answer
73 views

Can you build a camera obscura indoors, to watch a play upside-down as it's performed? [closed]

I've seen Youtube videos of people who have converted a room into a camera obscura to capture images of skyline/trees/clouds, but couldn't you capture indoor scenes too? Or would you need bright ...
0
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1answer
129 views

Projector Design and lenses

I am working on a project where I need to project a single image onto an object, Originally I was looking at the digital projector route but due to cost and complexity this has been ruled out. I found ...
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vote
1answer
94 views

Could someone please give simple explanation of “Principal plane” & “Nodal plane”?

I have read "cardinal point" on Wikipedia for number of times but still I can't get it. My English is not perfect. could someone please explain it in simple English?
2
votes
1answer
138 views

How to obtain 180° FOV and little optical errors?

I'm thinking about building an all-sky camera, i.e. an automated camera that points straight up to the zenith and that captures the entire sky down to the horizon. The idea is to capture celestial ...
2
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1answer
61 views

What are the (dis)advantages of moving the entire lens for focusing vs. only parts of it?

There's a lens adapter available that adapts Leica lenses to Sony mirrorless cameras. It's called TECHART PRO. The key feature is that it allows to use autofocus with the manual lenses. This works by ...
47
votes
8answers
20k views

Why do light sources appear as stars sometimes?

See for example this photo: From my experience, the longer the exposure the stronger can this effect be observed. Is this correct? Are there any other factors that influence the creation of these ...
3
votes
1answer
45 views

How is a lens distortion model performed? [duplicate]

So, as the title suggests, how is a lens distortion model (e.g. Brown-Conrady or pinhole camera model) applied on an image? I know it uses some calibration parameters (principal point's coords,focal ...
4
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2answers
1k views

Does wide angle equivalent in crop sensor skew image?

I see many posts on both this forum and elsewhere the discuss the use of a wide angle on a crop sensor. For example, they discuss how at 14mm lens is 14mm on a 35mm film or full frame, but with a ...
6
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2answers
169 views

How do lenses control “projection”?

How is a fisheye lens made differently from a normal ortholinear projection lens? How are real lenses acting differently from the ideal "thin lens" or pinhole, in terms of how the 3D scene in front ...
5
votes
5answers
243 views

Does sensor size impact the diffraction limit of a lens?

My understanding of diffraction, is that with a small aperture the 'airy disk' (which I understand is the pattern light from a given direction relative to the lens will form on passing through the ...
5
votes
4answers
637 views

Categorization of 14mm lens as rectilinear?

I used the Panasonic Lumix G Vario 14-42mm f/3.5 -5.6 Asph. / MEGA O.I.S. Lens to take a photo from my balcony. Here's the original RAW (ORF). The symptom I am experiencing is that different ...
11
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4answers
5k views

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

By definition, a prime lens is a fixed lens system with a fixed focal length. Then, simple physics tells us that it should be able to focus only on one plane (at a fixed distance) in front of it. But ...
1
vote
2answers
208 views

How do I design a secondary lens for my fixed-lens camera to narrow its field of view?

My goal is to put a lens or an array of lenses in front of my actioncam to use its high resolution for recording of undistorted normal-eyed footage, to avoid having to buy two cameras for the ...
21
votes
5answers
1k views

What is the shape of the focal plane?

This is something I just realised I don't entirely know the answer to, so I'm going to ask it here as I think it's interesting. In most non-scientific writing on depth of field, diagrams generally ...
2
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5answers
297 views

Why does it seem like large sensors are necessary for good low-light performance?

Phone manufacturers have recently started advertising the size of the photosites on smartphone camera sensors. They argue that larger photosites lead to better low-light performance. I think a good ...
6
votes
2answers
184 views

Do nano coatings actually make a difference?

Nikon famously has "nano coatings" on it's higher ended lens, and many photographers online swear that this visibly improves their images. However, it's not clear what the actual improvement is ...
7
votes
2answers
3k views

What are ED elements?

I find that some lenses are indicated with the letters "ED", referring to some special type of lens element. What are ED elements, and what advantages do they bring? Note that this question isn't ...
2
votes
1answer
170 views

Does a lens exist that is parfocal, has a linear zoom throw, and is affordable?

I'm working on a project to create, essentially, a servo-powered zoom lens, using a (D)SLR zoom, a zoom ring gear, and a stepper motor. After mounting the zoom ring gear, I'll attach a pinion gear to ...
0
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2answers
59 views

Nikon J1, takes pictures but they are all black, doesn't seem to “see” things, lens not the problem

I have a nikon J1, it has always worked well. Today I wanted to take a picture and the screen appeared black, like something was blocking the light completely or I was trying to take a picture of a ...
36
votes
3answers
3k views

How do I interpret an MTF Chart?

As part of how Canon (and other lens makers) give technical information about their lenses, they supply an MTF (Modulation Transfer Function) chart. How do I read and interpret what the chart is ...
2
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2answers
127 views

How do universal clip-on iPhone lenses work?

So, recently I see a lot of clip-on Universal iPhone lenses like this (aliexpress link). I have a CCTV camera at home. It has a lens which looks like this from m12lenses.com. Can I clamp these iPhone ...
11
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2answers
7k views

Why is depth of field affected by focal length?

As the focal length decreases, the depth of field increases as well. Why is this? I'm not so much interested in a physics lesson as I am interested in a simple, down-to-earth explanation.
10
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2answers
193 views

What model does Lightroom use for lens correction?

I use Adobe Lightroom to remove the barrel distortion from GoPro images. Does anyone know if this software uses the Brown-Conrady model to achieve the lens correction? If not which model does it use? ...
0
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2answers
87 views

Distortion Removal=Parallax Removal?

So, as the title suggests: does distortion removal caused by lenses means that the parallax is also removed from the pictures?
34
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5answers
7k views

How do constant aperture zoom lenses work?

Cheaper zoom lenses usually are faster at the wide end and slower at the long end (for example, the $150 Canon EF-S 18-55mm f/3.5-5.6). More expensive constant-aperture zoom lenses have the same ...
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4answers
127 views

Does aperture effect the “depth” of faces in a portrait? Wide aperture make noses look shorter, wrinkles less pronounced?

Having a debate with myself that F/10 makes my portraits look better by making faces have less "depth." What I mean is I feel like wider apertures such as f/4 make my nose look longer and wrinkles ...
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vote
5answers
3k views

Why image at 400mm is LARGER THAN DOUBLE of image at 200mm? (according to lens formula)

Like most of us, I thought it was yes. Until I really look into the Lens Equation: (1/subject distance) + (1/image distance) = (1/focal length) ...
18
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3answers
707 views

What is Chromatic Aberration?

What is Chromatic Aberration? Is it a physical part of the lens, or just an optical illusion?
2
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4answers
148 views

How can I fire two cameras simultaneously with different settings but the exact same view?

I have an idea I want to play around with and I was hoping something already exists for it but google has turned up nothing. I want to use two cameras synchronized to fire at the exact same time and ...
1
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1answer
64 views

If a lens has a 4% Barrel Distortion, what does that mean for images?

I know what barrel distortion is, but how do I take a 4% rating and relate that to an image?
21
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13answers
25k views

How does the lens diameter influence photo quality?

I have tested two different 50mm lenses in my camera. One was a Nikkor 50mm ∅52mm. The other one was a Sigma 50mm ∅72mm. I took some pictures with both lenses using the same setup for aperture and ...
1
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4answers
709 views

Why does crop factor apply with APS-C lenses, and why aren't these brighter than FF ones at same aperture?

I know that the image circle of FF-lenses is bigger than it needs to be on APS-C sensors, thus the FOV spears narrower. I've heard that APS-C lenses sit closer to the sensor, thus projecting a smaller ...
27
votes
3answers
8k views

What is a zone plate?

I was looking into alternative methods of photography and I happened upon something called a 'zone plate.' Three questions: What is a zone plate? How does it work? What can I do with it?
3
votes
2answers
303 views

How to compare the speed of lenses taking transmission into account?

When comparing the speed of two lenses, you almost exclusively hear about the maximum aperture. This of course makes sense, since at a certain lighting condition, a larger aperture in general allows a ...
16
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2answers
1k views

Does a specific f number across all lenses denote same amount of light?

When we say a light source emits 1500 lumens of light, it does not really matter if the light source is incandescent, CFL, diode etc. Similarly, when I say f/1.8 can I assume that all lenses pass the ...
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1answer
90 views

What is the fastest T Stop available?

What is the widest T Stop possible We are having f stops of below even 0.7 NASA lenses What will be the T stop of such lenses with f stop below ONE?
2
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3answers
135 views

Light Capture of Full-Frame Lens on Crop Body [duplicate]

Given two lenses: a full-frame lens and a crop lens, both at focal lengths necessary to capture the same frame on their respective systems and at the same f/stop. The physical size of the aperture ...
12
votes
3answers
15k views

What is the Chief Ray Angle (CRA)?

I want to select image sensors for a particular application. One term that I have come across regularly in their datasheets is the CRA. I was comparing 2 image sensors and although they were of ...
1
vote
3answers
248 views

What factors make a lens brighter? [duplicate]

Let's say I have two lenses of 50mm, one with maximum aperture f/1.8 and another with f/1.4. I understand that when using maximum aperture, for the latter lens more light will get to the film or ...
2
votes
2answers
180 views

What is the “airy disc”, in simple language?

In my understanding, this is relevant to photography because if you are shooting light of a certain wavelength (or primarily so, and such as: a blue scene), your aperture size can affect the sharpness ...
22
votes
2answers
2k views

Why is infrared light's focus point different from that of visible light?

When reading about infrared photography, it's often mentioned that IR's focus point is slightly different from visible light. Why is the focus point of infrared light point different from the focus ...
1
vote
1answer
158 views

How do wavefronts/wavelets propogate in three dimensions, and why is this important for photography?

The photography book I have talks about waveforms, but it doesn't do a good job of explaining them. So, here's my understanding from the book and google searches (it could be unbelievably wrong.) In ...
3
votes
1answer
161 views

Is it possible to make your own focus distance scale?

I'm using a Nikkor 18-105mm kit lens and it doesn't have a distance scale on its focus ring, is it possible to create your own distance scale by knowing the 0 and the infinity focusing points on the ...
2
votes
1answer
226 views

Why does the “fisheye effect” look stronger or weaker with different scenes taken with the same lens?

It seems that the fisheye effect can look different with the same lens. So I want to understand how it works. For example, I use a Dji Phantom vision 2 drone to take pictures, all of my pictures have ...
4
votes
3answers
589 views

Does focal length change when I adjust the focus? [duplicate]

When I adjust the focus of my camera, in general, does this affect the focal length? I have heard that it does.
34
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4answers
24k views

What does the number of elements and groups in a lens mean?

All lens specifications include a statement of how many elements the lens contains, and in how many groups, for example: Nikon AF-S VR Zoom-NIKKOR 70-300 mm 1:4,5-5,6G: 17 elements in 12 groups (two ...