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.

Filter by
Sorted by
Tagged with
5
votes
3answers
300 views

Why would lens be much longer than its focal length?

I accidentally saw Nikon 17-35mm f/2.8 lens and noted that it is rather large for its focal length. Here's the first review of this lens search offered - looks like it's 107 millimeters long. Given ...
1
vote
2answers
809 views

What function does C1, C2, and Off mean on Sigma 120-300mm f/2.8 Sports lens?

I am using a Sigma f/2.8 120-300mm lens. How does the C1 and C2 affect pictures? Also, what about the Off, 1, and 2 switch on the OS feature?
5
votes
1answer
94 views

Are focus and resolving power optically equivalent?

Limited "resolving power" or "sharpness" is a problem one can see with many lower-quality lenses, especially with higher-resolution camera bodies. Playing with my cheap 500mm mirror lens, I often get ...
0
votes
1answer
175 views

What causes this pattern? [closed]

What causes the pattern seen on the image (it is a still from a video)? This doesn't seem to be a Moiré. It seems to be largely related to the camera or the filter (the pattern is fixed and aligned ...
5
votes
4answers
313 views

A thin camera and a thin lens with a large glass element

After seeing these 3D designs, I was wondering if a camera that is thin could possibly have such a large piece of glass in the lens (given the lens piece doesn't expand when powered on). As far as I ...
4
votes
4answers
296 views

Is there an optical filter that reduces the film's contrast?

As far as I know, the change of the exposure moves the negative' density curve left or right only (moves the objects to the different zones), and to shrink or enlarge overall contrast, one has to ...
5
votes
1answer
224 views

Is there an easy way to tell the size of an image circle a lens has?

I know that lens can come in many formats, e.g. crops vs. full frame. However, someone recently told me that the Zeiss Otus has an image circle that is larger than the intended format. This is one ...
-3
votes
3answers
183 views

If a camera has two lenses, where is the focal plane? In the sensor or in the second lens?

For example, this exercises asks where is the focal plane. Is in the sensor or in the second lens?
2
votes
3answers
121 views

What limit do lens manufactures come upon first when making a wide range lens with large aperture (besides economics)? [duplicate]

Economies of selling such a lens would be my first guess to why a lens doesn't exist but I am more interested in the physical characteristics of a lens. How do the characteristics of a lens affect ...
0
votes
3answers
2k views

Understanding focus distance of Nikon f/1.8D lens with D5600 Camera

I took some sample photos using my Nikon D5600 camera with Nikon f/1.8D lens. I had to set the focus manually since this lens doesn't provide AF with my camera. My Question: The album of my sample ...
2
votes
1answer
154 views

How do phone attachment lenses affect depth of field?

Let's take, for example, the Moment Tele Lens. This lens is pitched as a 60mm lens that allows you to get 2x "closer" to the subject. The iPhone 6s uses a f/2.2 lens. Does the mounting of the tele ...
1
vote
3answers
123 views

Design and Fabricating My Own Lens

I have a small business (just me) selling an inspection machine. The camera and lens work well, but I've had to print my own camera mount to get the lens further away from the CCD to get a good focus....
0
votes
2answers
427 views

Does the sensor size matters in the size and weight of an equivalent lens? Why?

In other words, does the size of projected image circle matters in the size and weight of two lenses with the same aperture/DOF (different f-number) and field of view (different mm)? All other things ...
21
votes
3answers
5k views

Why is the hole in a pinhole camera usually a circle?

I know that for pinhole cameras and camera obscuras the holes are usually round (they are circular). But I don't see the link between the shape of the hole and the formation of the image.
2
votes
4answers
945 views

Do convex lenses make light from different points converge to different points?

I'm starting to study camera and lenses. Most of the sources online introduce you to the concept of convex lenses, with pictures similiar to this: This picture just show you that parallel rays (of ...
12
votes
3answers
2k views

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

I'm starting to study cameras and lenses. By reading explanations and watching videos on convex lenses, I learnt that they make parallel light rays converge to a single point called the focal point. ...
1
vote
2answers
387 views

What does lens flare from a catadioptric (mirror) lens look like?

Can one get lens flare with a mirror lens? What does it look like?
6
votes
1answer
228 views

Determining the size of the smallest resolvable detail for a given camera

My generic question: Given camera specifications, e.g: sensor resolution, sensor image area, pixel size (area), optical size, focal length (ratio), fov (horizontal and/or vertical) and ...
0
votes
2answers
156 views

Confused about different optical zoom on different lens [duplicate]

I'm looking at 3 different lens mainly for distance shots but with a bit of Macro occasionally. Tamron AF 70-300mm F/4-5.6 Nikon AF-S DX NIKKOR 55-300mm f/4.5-5.6G Sigma 70-300mm f4-5.6 The bit ...
1
vote
2answers
167 views

Color consistency across equal cameras but different lenses

I want to stitch images using equal cameras(Point Grey GS3-U3-41C6C-C) but with different lenses. One lense is a wide-angle lense (Sunex DSL318B-650-F2.4) and the other is a fish-eye lens (Fujinon ...
1
vote
2answers
273 views

How would apodization impact landscape photography?

I'm considering purchasing the Sony FE 100mm f2.8 STF GM OSS which just looks and feels incredible to me. I haven't been able to find any reviews, articles, or conversations though discussing the ...
1
vote
3answers
274 views

Is focal length internal or external? [duplicate]

I just wanted to check because I've encountered various distinctly different assertions. I was originally taught that focal length referred to the optimum distance from subject| ←→|lens, where ...
2
votes
1answer
579 views

How to measure field-of-view of a camera with fisheye Lens? [duplicate]

For a camera with a rectilinear lens a simple measurement would consist of taking images from known distance of an object of known size. For example using a sheet of paper as an object set on a wall ...
2
votes
1answer
521 views

What are these vertical light lines on pictures taken with my smartphone?

We are back from holidays and we notice many photos with strange vertical lines, see photos below. Can someone explain this optical effect to me, please? How can I avoid it in future? The pictures ...
1
vote
1answer
931 views

How do I clean a Yashica Mat-124g taking lens?

I have disassembled the taking lens of my Yashica Mat-124g and tried to clean it. First, I used 99% isopropyl alcohol and it didn't help. Then I used a 1:1 solution of hydrogen peroxide and ammonia ...
1
vote
6answers
569 views

Lens equivalent depth of field [duplicate]

This question is ported directly from Physics SE, because the guys there believe this is the right place for it. In digital photography, there's the principle of lens equivalency, according to which, ...
0
votes
2answers
587 views

How to prevent fringing? [duplicate]

When using my Tamron 16-300mm lens I frequently experience chromatic aberrations in my photos. how so I prevent this?
1
vote
1answer
406 views

Why might focus fall off at the edges?

In the John Wayne movie Rooster Cogburn (1975), there is a dramatic focus fall off at least 10% of the vertical height at both the top and bottom of the lens. Why does this happen?
3
votes
4answers
327 views

How do catadioptric camera systems show the whole frame despite mirror obstructing the center?

I am a beginner and I recently started reading about catadioptric systems. While I understand how they can be used to simulate longer focal lengths, I am still confused as to how the entire frame is ...
2
votes
1answer
167 views

What is a Proj.-Tessar lens?

I recently picked up a lens and an estate sale. "Carl Zeiss Jena No907646 proj-tessar 1:4,5 f=13,5cm." The 'proj' prefix led me to believe that it's a projector lens, but I'm not sure what kind of ...
4
votes
1answer
2k views

30x Optical Zoom vs. 30x Magnification on Binoculars? [duplicate]

I just recently learned that 30x Optical Zoom on a Camera and 30x Magnification on Binoculars are different things. Suppose if I have got 30x50 Binoculars, then what would be its equivalent number of ...
7
votes
3answers
4k views

What's the opposite of a fisheye lens?

I fisheye lens is an extremely wide-angle lens that is purposely designed to have extreme barrel distortion. Is there such a thing as a lens purposely designed to have pincushion distortion? What ...
0
votes
1answer
95 views

Size of an image given the mm of a lens [duplicate]

This comes from the world of video. I'm shooting an event with 20-300mm zoom lenses on HD video cameras. The cameras are physically 35 feet from the stage, given that information how tight of a shot ...
2
votes
4answers
299 views

Where is the aperture?

Where and how is the aperture placed inside a lens? How come the image is not affected (no obscuring) by something inside the lens literally blocking light?
0
votes
2answers
95 views

Need help to find proper camera and lens specification

Last day I shot using an 18-135mm Nikon lens, it was barely able to capture a fly-sized point at a distance of 100m with proper details. Using a 100-400mm lens would be too expensive. Can you guys ...
1
vote
3answers
889 views

What is the (real) meaning of binocular magnification number?

This is more of an optics measurements question than a photography question, so if you don't want it on the site, just delete it. I just couldn't think of a better match. Do binoculars, loupes, ...
5
votes
2answers
253 views

Do lens optics/formulas, of the same lens model number, get updated as it is being produced?

Context I've noticed that the Nikon 105/2.5 has a long history of having many different versions from Sonnar v Gauss design to coatings and different blade counts for the aperture. Most of these ...
4
votes
3answers
1k views

Is there any physical reason a mirror lens could not have a variable aperture?

I understand that mirror lenses already have high maximum apertures and that often, the last thing one wants to do is let in less light, but is there a physical reason that one could not build a ...
7
votes
3answers
4k views

Concept of focus for a pinhole camera?

Is there a concept of "focus" and thereby defocus for a pinhole camera? If yes, then what is it? If it is assumed that only one ray of light enters in through the pinhole from every point on the scene,...
0
votes
3answers
378 views

What differences will there be when stacking add-on lenses?

I wonder what the outcome will be of stacking a lens with add-ons like these: What's the difference between stacking these on the exterior compared to actually replacing the lens?
6
votes
6answers
1k views

Why is the area in focus in front of the focus distance narrower than behind it?

I guess the title and the picture explain my question well.
1
vote
3answers
2k views

Are there any 24-70 2.8 lens with no length change in zooming?

I'm planning to buy a 24-70 f/2.8 lens for my Canon 7D. I need a lens that won't increase its length while zooming (like the Canon 70-200mm series). Is there such a lens in any brand?
3
votes
2answers
188 views

What is the light called that is outside the area of the capture medium?

Is there a name for the light that passes through a lens and does not make it to the capture medium (sensor, film, other)? I'm looking for the name of the grey area in the following image from ...
2
votes
3answers
407 views

What's the intended use of lens with f-numbers close to or “faster” than f/1?

Lens with f/1.2 are rather expensive and not very widespread. Lens with f/0.95, f/0.85, f/0.8 do exist but they are also very expensive and quite rare. Lens with f/0.7 are so rare that some of them ...
4
votes
3answers
868 views

Are thermal imagers inherently more expensive than visible-light digital cameras?

We're finally starting to see practical thermal imaging sensors (microbolometers) entering the consumer market. However, they are still vastly more expensive than comparable visible imaging sensors. ...
8
votes
3answers
2k views

What are groups and elements in lenses?

I hear people talking about groups and elements in lenses, but I am not sure what they mean. Could someone please explain?
11
votes
5answers
2k views

Is a two-prime lens possible? E.g. 35mm and 50mm

I really like prime lenses for their simplicity, zooming with my feet. I prefer it to a zoom lens because of this simplicity. But I do carry both a 35mm and 50mm because I do two different things ...
17
votes
4answers
4k views

What is the difference between perspective distortion and barrel or pincushion distortion?

I've heard of: perspective distortion barrel distortion pincushion distortion mustache distortion What are these different types of distortion, and how do they relate? What causes them, and can they ...
4
votes
5answers
444 views

How does a 'reversing adapter with automatic system' deal with the *inverseness* of the reversed lens?

First, I apologize because I don't know the exact name for this kind of adapter. (Please mention the correct term for that kind of adapters...(I mean those reversing adapters that can keep the lens's ...
0
votes
1answer
129 views

Numerical Aperture of an Inverted Webcam Lens

I have inverted the lens on a webcam to create a webcam microscope. For illumination , I am using an led array. For the project that I am doing I need to know what the NA of the lens, but I am ...