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Questions tagged [optics]

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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Calculating FOV for mismatched lens/sensor size

I have this 50mm lens that gives the FOV for a 2/3" sensor in its spec sheet: Diagonal: 12.6° Horizontal: 10.1° Vertical: 7.6° I have this camera, which, according to its spec sheet, has a 1/2....
Jason C's user avatar
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5 answers
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Why does viewing the sun through a telescope burn your eyes?

First a disclaimer: I KNOW that viewing the sun through a telescope will burn my eyes, so no need to convince me of that. I'm not going to try it. This question is about the optics and physics of why ...
Ben Hershey's user avatar
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IR Camera artifact can anyone clarify

I was wondering if anyone here could shed light on the recent “Jellyfish UFO” video recently reported on. This looks like bird poo on the housing to me, yet I am no expert and know very little about ...
Guest's user avatar
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2 answers
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DOF of line scan camera & lens

I came across this method of calculating the DOF that involves pre-calculating the camera CoC. The same method can be used for lineScan cameras? What is the Coc of 16K linescan camera (Cmos Sensor 4x ...
user114164's user avatar
2 votes
3 answers
105 views

Basic Lens Advice For Machine Vision Camera

I'm working on an application that requires taking photos with a machine vision camera in outdoor areas with a wide range of lighting conditions. I have been taking some sample photos and no matter ...
CameraTuner2020's user avatar
1 vote
2 answers
144 views

Optical Vignetting

I was reading Edmund Optics application notes on relative illumination, which talks about what it is, its affects, its drawbacks, positive aspects and so on. However, out of all the types of ...
vannira's user avatar
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2 answers
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Which of these lenses to choose for a studio project?

I'm preparing for my first professional studio photography project and am seeking advice on the best lens to use for portraits, including full-body shots and headshots. I have a Canon EOS RP with an ...
adamasan's user avatar
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3 answers
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Why has no phone manufacturer tried a lens turret system yet?

Early 35mm film cameras, esp. movie ones, used lens turrets, ie. a ring with 3 or more pre-mounted lenses that you would rotate to switch between lenses. I'm talking about this: I do wonder - why not ...
Piotr Chylarecki's user avatar
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4 answers
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If focal length does not affect DOF, why doesn't a 25mm lens at an f-stop of 4 give me the same DOF as a 100mm on an f-stop of 16?

After having spent some time reading about DOF and the derivation of its formula, I tried calculating the theoretical DOF of different lenses. Now to my knowledge, a camera using a lens with a focal ...
vannira's user avatar
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3 votes
3 answers
248 views

Does the inverse square law apply to all lights, including light within a lens?

In The Cine Lens Manual by Jay Holben and Christopher Probst pp.46, it is mentioned that the light loses brightness/intensity even within the lens. This part is discussed right after the inverse ...
Amarth Gûl's user avatar
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What Nikon lens is this? What kind of UV-pass beam splitter is this?

A detective challenge for this wonderful community of experts: I am working on a science museum exhibit about the different ways animals can see light. I am trying to reverse engineer the incredible ...
Robb Godshaw's user avatar
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2 answers
2k views

What can cause double-vision effect in slightly out of focus areas?

I have an issue with my Canon 70-200 F/4L USM. It is less sharp at 200mm than at shorter range and the objects that are slightly out of focus are rendered twice with horizontal offset. The shutter ...
Bartek Kudzia's user avatar
1 vote
2 answers
137 views

Calculating bellows factor (etc) when using a magnifier lens

The bellows extension formula takes the focal length and draw as input and produces an exposure compensation as an output. A Nikon 4T magnifier is a -2.9 diopter lens. Sticking it on the front would ...
bmargulies's user avatar
1 vote
1 answer
96 views

Does image distance affect resolution?

I want to adapt the lens from a Minolta Dimage Scan Elite 5400 onto a Raspberry Pi HD camera. Going off this article: https://www.closeuphotography.com/minolta-dimage-scan-elite-5400-lens/ the lens ...
Christian Chapman's user avatar
2 votes
3 answers
785 views

How to calculate the required working distance for an object to fill the camera sensor?

I would like to take photographs of a flat object with the camera at some adjustable distance from this object. I would like the object to just fill the camera's sensor. Given an object of extent $s$, ...
kevinkayaks's user avatar
1 vote
3 answers
95 views

Does unit focussing yield smaller depth of field than element focussing?

With unit focussing (also called bellows focussing, although a bellows isn’t intrinsically necessary) the entire photographic objective is moved relative to the film plane to set the focus. This also ...
Daphne Preston-Kendal's user avatar
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2 answers
80 views

Calculating lens distances with a magnifying lens [duplicate]

I have a Nikon 4T close up lens to attach to a Nikon 120mm large format macro lens. The 4T is 2.9 diopter / magnification factor 0.11. The usual equation is $${1\over \text{focal length}} = {1\over \...
bmargulies's user avatar
2 votes
1 answer
90 views

Relationship between quad bayer sensor and the CMOS size

I have developed Python code to take an image produced by a DJI drone (and several other GNSS Cameras) and georeference the images. Basically the code reads the EXIF data from the individual images. ...
GBG's user avatar
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2 answers
127 views

What lens do I need?

I am looking to mimic the below photos to the best of my ability. Hue, the softness of the photo, cool toned, range of view, etc. I have a Sony a7III. I understand editing is done to the photo after ...
DREW's user avatar
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1 vote
3 answers
557 views

What is the cause of the "red ring" lens flare?

I've been studying lens flares and the various phenomena that occur alongside the reflected "ghosts" that are most commonly associated with them. Of particular interest are the red rings ...
Devereaux McGill's user avatar
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1 answer
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If I collimate light with a couple lens, how do I find the magnification?

Say I have an object at 40 cm from a convex 20 cm focal length lens, then a concave -30 cm focal length lens 10 cm behind that. This would give an image at infinity, which one could take a picture of, ...
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2 answers
182 views

I want to measure far distance focus in a short space, but give myself a greater FOV, how would I do that?

Building off of this question, say I put a 1 m lens in front of a camera so I can see a virtual image at 500 m to focus to, when I place an object within the focal length (0.998 m), but I want a ...
user avatar
0 votes
2 answers
140 views

I want to focus at far distances but close, what lens could I use?

I want to be able to set the focus at far distances, like 500 m, but in a smaller setting, like 5 m. What lens could I use to achieve this? I have found this lens that achieves it for a FOV of 120 ...
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-1 votes
1 answer
185 views

Could I have destroyed my Lumix GX80 by taking sun photos?

So I shooted architecture photos during a cloudy day but the lighting was very bright and you could see sun directly in some moments. I was shooting and I noticed that I needed to adjust aperture (...
Josip Vrandečić's user avatar
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4 answers
1k views

Which is the cause of Barrel and Pincushion distortion?

Barrel and Pincushion distortion are due to the fact that the magnification of the lens changes as you get further off axis. Let's consider a single thin lens with an aperture stop. These two pictures ...
Kinka-Byo's user avatar
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0 votes
3 answers
191 views

Why do some lenses have a rounded front element?

I've noticed that some lenses, mainly wide-angle or fisheye (e.g. Samyang 14mm f/2.8, or Nikkor 8-15mm fisheye) have a rounded front element. Which is the reason for it? It's of course limiting in ...
Kinka-Byo's user avatar
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0 votes
1 answer
126 views

How can a fixed-focus lens have a focus range of 0.5 meters to infinity?

I have a Mavic Air 1 drone and I was wondering how the camera of this drone can have a shooting range as large as 0.5 meters to infinity with a fixed focus? Mavic Air 1 camera specs: Parameter Value ...
Sebastyen Laroche's user avatar
3 votes
1 answer
605 views

What determines the image circle diameter?

Anywhere in the web it's stated that the image circle diameter depends on the lens design. I'm curious to understand it a bit better. Let's start with basics. Let's consider a single thin lens ...
Kinka-Byo's user avatar
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0 answers
73 views

Why binoculars have magnification number, but lenses don't [duplicate]

I got into birding recently and got a pair of 10x42 binoculars and got a camera with a crop ratio of 1.6 and a 100-400mm (focal length) lens. With binoculars and spotting scopes everything seems easy -...
eddyP23's user avatar
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4 votes
2 answers
1k views

How can I find a lens locking screw if I have lost the original one?

I have an industrial camera with a C-mount lens, like this one: (Source of image, last accessed 2022.11.02.) You can see a tiny screw on the top of the picture. It is used to lock the focus ring or ...
LimeAndConconut's user avatar
1 vote
1 answer
87 views

Determining fstop when designing a camera?

I am designing a camera for a project. How do I determine its fstop number if I am designing it? The equation I have is: fstop=f/D where f is the focal length and D is the aperture diameter. I have ...
SS1's user avatar
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1 vote
0 answers
75 views

Do these Camera parameters make sense?

I need to pick a Camera to see a target at ~5km. Visible Spectrum Pixel size 5 microns (guessed). Range 5000m Target height 2m IFOV = 0.125 m so I get 16 pixels on the target at 5000 m. Focal Length = ...
SS1's user avatar
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0 votes
3 answers
490 views

Understanding Entrance Pupil

let's consider a simple lens without diaphragm. For a lens like this, the book Science for Curious Photographer states that: The important fact is that the illumination of the image is proportional ...
Kinka-Byo's user avatar
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1 vote
3 answers
135 views

How does an afocal lens produce an image on a screen?

I'm really confused about it. If such a lens is necessarily focused at infinity and does not have a plan of focus, then, does it mean it can produce a clear picture on a screen, no matter how close it ...
Zmaragdinae's user avatar
2 votes
1 answer
165 views

What causes photos from modern instant films cameras to look unique?

I just saw a picture from a friends Polaroid Instant Camera or Fujifilm Instax, and even when it is freshly developed (no aging or anything) the pictures have a distinctive "look", like a ...
itisyeetimetoday's user avatar
0 votes
3 answers
197 views

Do photographic lens show virtual image if the subject distance is less than focal length?

A convex thin lens produces a real inverted image if the subject distance from the lens is higher than the focal lens. If it is lower, the image will be virtual. Of course a virtual image appears on ...
Kinka-Byo's user avatar
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0 votes
3 answers
224 views

Clarifications about the Reproduction Ratio Formula

The reproduction ratio formula is: ...
Kinka-Byo's user avatar
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4 votes
1 answer
266 views

What lens would suit an A4 large format camera

I'm planning on building a scanner camera. The principle of which is simple: everything's built like a large format camera, except the film is a simple scanner controlled by computer. Now, building ...
Zmaragdinae's user avatar
1 vote
2 answers
39 views

Identifying and replacing a lens of a 360° Giroptic camera (360cam)

I broke a lens of a Giroptic 360cam. It is discontinued by the manufacturer and even the company does not exist anymore. Here is a link from the internet archive. All the tech specs I found is those: ...
Alex's user avatar
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1 vote
0 answers
42 views

Smear/spread at the edges of a phone lens [duplicate]

My google-fu is failing me on this, because I don't know the term I'm looking for. At the edges of a simple group shot of five or six people taken with a smartphone, there is a tendency for the faces ...
Tetsujin's user avatar
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0 votes
2 answers
121 views

Why does the rainbow change into a green light when zooming using iphone

The rainbow is created with Kikkerland rainbow maker. When zooming with an iPhone the image abruptly changes at 2x zoom to a green light. What is the physics behind this?
Albert's user avatar
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0 answers
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Recreate this lens specification

So my Samsung note 10 details say this about their telephoto lens 12 MP, f/2.1, 52mm (telephoto), 1/3.6", 1.0µm, PDAF, OIS, 2x optical zoom. I tried using it to see through my peephole which has ...
Green Giant's user avatar
3 votes
3 answers
520 views

How does subject distance get calculated if you shoot using a mirror?

Let's say I am at a gym and need to take a photograph of myself. I can hold out my hand with my D80 to take a picture of myself but the perspective compression would make my face look like Mr. big ...
Delta Oscar Uniform's user avatar
0 votes
2 answers
556 views

Putting telephoto lens on top of an OEM lens?

I want to use something like a Wyze Cam v3. Many users have removed the original lens and put on a telephoto lens. I dont want to remove the OEM lens. Can I put a telephoto lens on top of the original?...
Green Giant's user avatar
0 votes
2 answers
210 views

How do sensors "focus" on the bottom of the lens (flange distance)?

I know that when a camera sensor is used with a lens there is a specific distance between the sensor and bottom of the lens (aka "Flange distance" or "flange focal distance") in a ...
Ray's user avatar
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1 vote
2 answers
255 views

How do I determine the focal length of a simple meniscus lens empirically?

I have a camera (Bolta Photavit IV) with a simple reverse Galilean finder that is missing the rear element (this is a common problem, they fall out). If I have a complete finder and disassemble it, ...
Bob Macaroni McStevens's user avatar
0 votes
1 answer
231 views

How does using more spherical lenses compensate for spherical aberration?

I've heard of three common ways to compensate for spherical aberration: Small aperture (fewer non-paraxial rays). Aspheric lens (compensate with lens shape/material). Corrective spherical lens ...
JDN's user avatar
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2 votes
6 answers
227 views

Why smaller AoV APS-C has same aperture as larger AoV FF lens?

I am quite confused, FF focal length 50mm f/2.0 has aperture diameter 25mm APS-C lens 50mm f/2.0 has aperture diameter 25mm Then both lenses have same size front glass. However Angle of View for lens ...
LilBro's user avatar
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1 vote
4 answers
216 views

Decrease FF lens focal length for use on APS-C and still have it focus?

Need to convert very cheap vintage FF 50mm f/2.8 lens to work as 35mm lens for for APS-C, for having wider angle of view. Its kind of works by simply placing lens closer to camera sensor (without ...
LilBro's user avatar
  • 197
2 votes
3 answers
218 views

Projecting image on camera

I have an optical system that forms an image at various distances (25cm range) as shown in the figure here: What kind of optics is required to project this image onto a CCD camera but without having ...
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