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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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2answers
85 views

Why does the same f-number mean same amount of light? [duplicate]

Intuition tells me that a bigger lens will collect more light with the same f-number than a small lens. But photographers tell me I am wrong. I cannot understand why. There are quite a few posts both ...
7
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5answers
1k views

Do bigger focal lengths capture more light?

I never understood what the f really stands for in the f-stop values, like f/1.8. Wikipedia explains it in various articles, but I still find it very confusing. What I understand, though, is that it ...
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2answers
92 views

What is the importance of the back focal length of a lens?

What is the effect and importance of the back focal length of a lens? For instance, if I look at these two lenses by Ricoh, they have the same focal length and aperture, but their back focal lengths ...
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4answers
2k views

How can a super tiny iPhone 6 Plus lens produce significant DOF?

According to Apple specs the iPhone 6 Plus thickness is 0.28 inch (7.1 mm) and the lens length is only a part of that. And according to an article I found, Depth of Field is a function of "aperture ...
100
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7answers
8k views

What is bokeh, exactly?

I understand that "bokeh" refers to out-of-focus areas of an image — but there is obviously more to it than that. What does the term mean exactly? How well is bokeh really understood? Is it purely ...
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1answer
100 views

Lenses round ..Photographs square shaped why? [duplicate]

If camera lenses are round then why is the photograph taken by the camera is square-shaped? photography
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5answers
2k views

How does a circular lens produce rectangular shots?

Is it something like the sensor captures a circular image and then what we get is the cropped version? Something like this: Or did I get it completely wrong?
40
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6answers
15k 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 ...
18
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6answers
3k 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 ...
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1answer
961 views

What makes the Zeiss Otus 1.4/55 so special?

The new Zeiss Otus 55mm f/1.4 is nearly $4000. With faster lenses from Canon (50mm f/1.2L) with autofocus, why is the zeiss lens more than twice that of the Canon counterpart?
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3answers
6k views

What makes a Carl Zeiss lens so special in a smartphone?

There are smartphones on the market that have a focus towards photography. Some are equipped with a Carl Zeiss lens. I have looked into Wikipedia, which tells me that they are a brand who produces ...
2
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2answers
166 views

What do resolution figures mean in lens specifications?

I'm working in computer vision and choosing the right lens is obviously as critical as having a good sensor if you're going for quality inspection (for example). Sadly I have very little experience ...
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6answers
8k views

What is a “diffraction limit”?

I've seen the term used, but what is a "diffraction limit", when should I worry about it, and what undesirable effects are a result of it ?
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4answers
6k views

Why are objects far away inverted through a lens but not through the viewfinder?

When I look through a lens the image of objects far away are inverted but when looking the the viewfinder on my camera they are not. Why is this? I am having a hard time understanding why objects far ...
3
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2answers
279 views

How to determine if a new lens is a subpar copy?

I have read some posts like the ones below about testing a lens to determine how well it performs optically. What I didn't see was anything on determining whether the lens performs as it should and is ...
14
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5answers
12k views

What is “infinity focus”?

I have been reading a bit about astrophotography and the term infinity focus keeps coming up. What is infinity focus and how do you set the camera to infinity focus?
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2answers
5k 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?
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1answer
147 views

Explanation of the fisheye phenomenon

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 ...
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0answers
34 views

Technical book or resource (non-creative) [duplicate]

I'd like a resource from which to learn about technical, non-artistic/technique aspects, such as: Onion ring bokeh, and what causes it. Choosing of lens hoods, Why chromatic aberration happens/why ...
7
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1answer
195 views

How is Nikon's PF optics different from and similar to Canon's DO optics?

Nikon has just announced a new 300 mm lens featuring a new technology called "PF" or "Phase Fresnel." This has been compared to Canon's existing DO (Diffractive Optics) lenses such as the 400 mm f4 ...
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4answers
1k views

35mm vs 40mm: Does it matter?

I want to buy the lens Voigtlander Nokton 40mm F1.4, $449 Voigtlander Nokton 35mm F1.4, $629 I am asking, why the slightly difference in focal length, the price difference in so much as $180? ...
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1answer
66 views

Why do I need an add-on lens to take smartphone macro photos?

Why do you need an external macro lens for a smartphone to take macro photos. Why can't the smartphone lens itself take macro photos?
40
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2answers
18k views

What is the difference between a pentaprism and a pentamirror?

Higher-end SLR cameras include a pentaprism to transmit the image from the lens to the viewfinder, whereas lower-end SLR cameras use a pentamirror to accomplish the same task. What are the ...
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1answer
152 views

How do add on macro smartphone lenses allow you to take macro photos?

It may sound obvious, but how exactly does an add on macro lens allow you to take close up photos? Can someone give technical reasons? I'd like to know the physics behind add on macro lenses and how ...
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0answers
58 views

How can I calculate the effect of a supplementary close-up lens (a.k.a macro filter)?

If I have a +1, +2, +4, or +10 close-up lens which attaches to the front of my regular lens, how can I calculate its effect on close focusing distance, figure out how much magnification I can get from ...
14
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1answer
848 views

How does a macro lens focus so close?

How does a macro lens focus so closely and how is the system different to that of a non-macro lens?
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1answer
92 views

Where do rays of light from one point strike the film?

I am a programmer and I am doing a camera simulation, I am stuck in a matter of how to know where does every ray of light incident after traveling through the lens, every point of the object will give ...
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3answers
130 views

How to estimate the minimum magnification to capture features of a certain size?

What is the correct way to estimate the minimum magnification (maximum subject distance) at which features of a certain size are resolved? My thinking is that given a system capable of resolving a ...
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0answers
60 views

Where is the focal point of a camera lens? [duplicate]

If the distance between the center of the lens and the film is called Focal length, does that mean the focal point of the camera lens is located on the film?
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2answers
145 views

What is the maximum aperture consistent with the Nikon F-mount?

In a related thread, it's been debated whether there is a hard limitation to maximum possible lens aperture; it seems there is none. However, using the example of the nikon F mount, this technical ...
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2answers
355 views

In what way does the lens mount limit the maximum possible aperture of a lens?

In many answers to questions about different aspects of really large aperture lenses it's pointed out that the lens mount sets a hard limit on the maximum possible aperture of the lenses to that ...
3
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3answers
213 views

How can the focal length of a lens be many times greater than the lens's physical length?

I bought a Tamron 16-300. Question is: how can it have a focal length 0f 300 mm when it is only about 30 mm long? Doesn't the lens have to be 300 mm from the sensing element?
9
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6answers
5k views

Technically, why is the out of focus area blurred more when using a bigger aperture?

I'm wondering, technically, why and how does the out of focus areas blur more when using a bigger aperture. I think it'd help a lot if I presented a problem that's been driving me nuts for a long ...
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3answers
456 views

What is the Leica look?

What is the Leica look that fans of the company claim is unique to them? What concrete differences are there that are most obvious to a layman?
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2answers
674 views

Why are large zoom ratio constant apertures lenses not generally available?

I know about 17-55 f2.8 and the likes of it, but I am talking about something say 18-135 f2.8. There exists 70-200mm f2.8 and the range (200-70 = 130mm) is much bigger than in 18-135. I am aware of ...
3
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4answers
2k views

Why Isn't This Photograph Pin Sharp?

I Have Been Trying Out My New Canon EF 24-70mm and I'm pretty underwhelmed by its sharpness. Here is a RAW file shot from a solid tripod on an (almost) windless day using a remote. Obviously it ...
6
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1answer
148 views

Can the method from the paper “High-Quality Computational Imaging Through Simple Lenses” compete with conventional lenses?

This answer to another question of mine linked to an interesting article: High-Quality Computational Imaging Through Simple Lenses. It proposes the use of simple optics and computational photography ...
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4answers
346 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 ...
3
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4answers
1k views

Differences between canon 17-85mm and 18-55mm

I was given a 450d with a canon 17-85mm lens, it has USM and image stabilzing. It has always seemed okay to me but after a few years i have decided to upgrade to the 700d, which has now come with a ...
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0answers
43 views

Technical question about aperture and lens [duplicate]

F stop = focal length / iris diameter So for example, my Lumix 20mm pancake, f1.7, has iris diameter of 12mm at that f stop, correct? So if Panasonic wanted to make a faster lens, could they do it ...
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0answers
46 views

What defines camera's size? [duplicate]

Smartphone cameras are small while others are big. I know some functions like zoom can change physical size, etc. So, ignoring a zoom lens, what defines a camera lens? I want to get the general idea ...
0
votes
1answer
82 views

Pentax k-30: can i buy all lens not stabilized?

I'm interested to buy a Pentax K-30. I'm wondering : can I buy not stabilized optics because of body' stabilized sensor ? Is the overall image quality comparable to an optic with stabilizer (like ...
30
votes
3answers
15k 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 ...
5
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2answers
2k views

Is it normal for focal length to change while focusing?

When I change the focus distance on my Pentax 55-300mm lens, the focal length appears to change. More specifically, the lens appears to zoom in as I focus towards the minimum focusing distance. This ...
6
votes
2answers
1k views

How does an apodization filter improve bokeh?

The new Fujifilm Fujinon XF56mmF1.2 R APD has an "apodization" filter, which Fujifilm says "smoothes the outline of the subject to create a more natural bokeh effect". The Wikipedia article on ...
19
votes
3answers
6k views

How does the human eye compare to modern cameras and lenses?

A goal in most photography is to present a scene which resembles what a person who had been there at that moment would have seen. Even when intentionally working outside of that, human vision is the ...
2
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1answer
147 views

How does a focus ring bring a subject in or out of focus?

When you manually adjust your focus ring on the lens, what actually happens inside the lens? Is this changing simply the point at which the lens is focusing, so that anything at this distance away ...
2
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4answers
136 views

Should lenses of equal quality for smaller sensors be cheaper?

In theory do we expect lenses of identical specs and quality to be cheaper when designed for smaller sensors? My expectation is that the answer is yes, because all of the things that lenses struggle ...
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3answers
1k views

What does “maximum aperture” mean in a camera spec? Where can I get the full aperture range?

I own a Canon S95, and am considering getting a newer model (e.g. Canon S110 or S120), and I'm comparing the specs. According to DPReview.com, the S95 has a maximum aperture of F2.0-F4.9, and the S110 ...
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1answer
62 views

Is there an “optimal” background distance when striving for a minimally distracting background?

Let's assume a thin lens and an object O in focus at a distance of dO from the lens. Further, let's assume there's a large out-of-focus background object B at a distance of dB. Now, we know ...