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Of and relating to the specifics of lens construction and manufacture.

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0
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1answer
84 views

How do lenses focus? (and zoom?) [duplicate]

My understanding of focal length is that it is the distance from the lens to the sensor; in my observations: higher focal lengths make for longer lens. Then I started thinking about how a lens ...
21
votes
4answers
2k views

Is it physically possible to build a long zoom (17-300 mm for example) at an aperture value of around 1.4 or 1.2?

I'm curious if the physics allow a company to build such a lens of course with good IQ, minimal color aberration, maximum sharpness, and little to none lens vignetting or edge softness
0
votes
3answers
117 views

Why don't we have a single lens e.g. say a 18-200 f/1.2 lens for the SLR camera? [duplicate]

Right now we have multiple interchangeable lenses. So why don't we have a single lens, say a 18-200 f/1.2 lens? Are camera manufacturers deliberately avoiding that or it is that it is physically ...
0
votes
1answer
235 views

What is an electromagnetic diaphragm?

What is an electromagnetic diaphragm, how it works, and how is it different with regular diaphragms? A specialized electromagnetic diaphragm mechanism operates in precise sync with the camera's ...
17
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2answers
1k views

Are there any secrets in lens design?

Lens manufacturers usually share diagrams like this for their products. However, they conspicuously omit specifications that would allow one to completely analyze the optical system, like the power ...
2
votes
6answers
211 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 ...
14
votes
3answers
300 views

What lens design limits derive from the width of the lens mount?

I'm familiar with the lens design limitations imposed by the flange-to-focal-plane distance. But what constraints are caused by the width of the lens mount (that is, the size of the hole in the ...
2
votes
2answers
177 views

Are there lenses that exhibit absolutely no focus breathing?

As noted here focus breathing can be problematic, especially for macro focus stacking. Are there lenses that exhibit absolutely no focus breathing? Is there some way to find lenses that minimize ...
3
votes
2answers
184 views

How does the Sony 135 F2.8 [T4.5] STF twin aperture lens design work?

I stumbled across the Sony 135 F2.8 [T4.5] STF other day. I have read through the review but I can't for the life of me figure out what the twin-aperture setup is supposed to do!
3
votes
1answer
93 views

How is focus-breathing controlled in lens design?

Answers here note that minimizing focus-breathing is especially desirable for cine lenses, and that it is one of the common features of those higher-end lenses. How is it achieved? Also noteworthy ...
1
vote
1answer
85 views

Why don't all zoom lenses have variable f-numbers? [duplicate]

As I understand it, the f-number is a ratio between the focal length and the aperture diameter. A zoom lens can change focal length, but shouldn't the maximum aperture be a fixed size? If so, that ...
10
votes
3answers
541 views

What is the limiting factor in lens construction when it comes to f-stop values?

This widely praised Nikon 105mm macro lens has a maximum f-stop value of 2.8. I've held it in my hands, it's a big lens. Meanwhile, this 50mm Nikon lens can go up to f/1.2, despite being 25% cheaper ...
7
votes
4answers
4k views

What are the advantages of a lens having a fixed maximum aperture?

What are the advantages of a lens having a Fixed Maximum Aperture? Previous answers have indicated that "pros tend to want constant apertures in zoom lenses". While in general lenses with a fixed ...
0
votes
2answers
1k views

What kind of lens are used in mobile phones?

Usually what kind of lens are used in mobile phones. I mean of the types similar to convex, concave etc.. Are they fixed focal length usually? How do we get the focal length of camera from digital ...
1
vote
4answers
109 views

What lens designs are sharper than a pinhole lens but also allow for multi-month exposures?

I have a homemade pinhole camera (film) that I use for taking super long exposures (multiple months). And while the results are fun, I would like to improve the sharpness of the image. Is diffraction ...
1
vote
3answers
209 views

Why did manufactures stop including DOF scales on lenses?

Seriously why? I hate it and I hate memorizing it or check my phone app for the depth of field of the current aperture. I find it so useful in old lenses. The DOP preview doesn't help that much (IMO) ...
14
votes
4answers
22k views

How does a spherical lens differ from an aspherical lens?

Many lenses (like the Pentax DA 15mm f/4 Limited, or the Nikon AF-S 35mm f/1.4G) are described as having "aspherical lens elements". Does this mean that regular lenses are spherical lenses? What's the ...
27
votes
2answers
3k views

What characteristics make a lens good or bad?

When reading lens reviews on the Internet, I often find subjective statements about the image quality that a lens produces, such as "good contrast" or "sharp". The problem is that I don't think I am ...
0
votes
0answers
86 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 ...
1
vote
3answers
440 views

Could a phone-camera have a medium-telephoto lens and still fit in a phone?

[to keep it simple, all focal lengths noted are 35mm equivalents; crop factors for phone cameras are about 7-8x, give or take] As far as I can tell most new phone cameras have a fixed, medium-wide ...
3
votes
2answers
180 views

Why do superzoom designs keep expanding on the telephoto rather than wide-angle end?

Why do bridge/semipro/superzoom camera manufacturers keep increasing the telephoto end rather than the wide-angle end? For example, the Nikon P900 has a 35 mm-equivalent focal length of 24 to 2000 ...
1
vote
2answers
148 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 ...
0
votes
1answer
442 views

Nikon 50mm 1.8g vs 1.8d? [duplicate]

What are some pros and cons of each? I use a Nikon D600 and am looking for my 50mm. I shoot a lot of video, so a smooth manual control is important to me. Besides that, I am unsure of what exactly I ...
-1
votes
2answers
99 views

How much zoom does a lens need to have before we call it a superzoom lens?

I've read that superzoom lenses have poor image quality, but how much zoom does a lens need to have before we call it a superzoom lens? 3x is certainly not a superzoom, while 10x probably is. ...
6
votes
1answer
1k 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?
0
votes
1answer
142 views

Do mobile cameras ever vary f stops?

I've been trying to get my head around the camera in my newly-bought Chinese mobile phone. I wonder how focusing actually works in these kind of phones. I imagine that in the standard context of ...
0
votes
1answer
145 views

camera mobile phone takes pictures at constant focal length if 3.5 mm.supposed to have autofocus and touchfocus [duplicate]

This is a cheap Chinese landvo l200 Android mtk65xx mobile The onlything it keeps Changing is IS0 from 150 to 800 + And exposure time I wondered how can it autofocus and touch Focus when it keeps ...
1
vote
3answers
182 views

What are the differences between pictures shot with spherical and aspherical lenses? [duplicate]

I read about some differences between spherical and aspherical lenses. Mostly about geometry though. I was wondering what is the difference on the pictures. How are the pictures of an aspherical ...
14
votes
1answer
903 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?
0
votes
1answer
149 views

How are aperture changes implemented on D-series Nikkor lenses?

Nikkor G lenses have a built-in USM motor that permits auto-focusing on bodies with or without the focus motor. They also permit changing the aperture from the aperture dial on the body. Nikkor G ...
20
votes
3answers
3k views

Why do wide angle prime lenses have relatively small apertures?

I've noticed that many of the wide angle prime lenses (at least for Canon) have somewhat smaller apertures than their normal or telephoto counterparts. E.g. the regular Canon 24mm prime is f/2.8 while ...
2
votes
1answer
116 views

do mirrorless camera lenses have automatic diaphragms

Do mirrorless cameras have lenses with automatic diaphragms like DSLRs or are you able to focus and view through the working aperture because of their electronic viewfinders?
4
votes
2answers
177 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 ...
8
votes
2answers
411 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
votes
3answers
287 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?
13
votes
3answers
525 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?
2
votes
1answer
70 views

Does Sony DT 18-135mm SAM lens has Full-time Manual focus feature

I checked it in Len user-manual but Sony didn't mention about Full-time manual feature. I also checked it on Sony website but I didn't find any resources too. Does anyone know the Len has Full-time ...
6
votes
1answer
161 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 ...
8
votes
3answers
842 views

What is a pump zoom lens?

While browsing for cheap second hand lenses I found the Cosina 70-210mm f4.5-5.6. The seller notes that it's a pump zoom. Googling the term does yield some results, but these simply state that a ...
2
votes
2answers
394 views

How effective are the rear weather sealing rings on lenses?

I am kinda torn between buying a Sigma 18-35mm f1.8, Nikkor 17-55 f2.8 and Sigma 17-50 f2.8 for my D3100 and D7100 cameras. The reason for confusion is that the Nikkor one has a weather sealing ring ...
1
vote
4answers
445 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 ...
1
vote
3answers
211 views

Why can lenses only focus from so close? [duplicate]

I have always wondered, why is it that a lens can only focus from so far away from the subject? I know some lenses have a kind of macro switch which basically allows them to focus closer but why are ...
4
votes
4answers
3k 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 ...
2
votes
4answers
461 views

What did the “macro” switch/mode do on older zoom lenses?

I remember that a number of older (80s to maybe mid 90s) zooms had a "macro" mode where you would throw a switch that allowed the lens to focus closer. What was that? was it just a built in extension ...
12
votes
2answers
432 views

Does focus breathing make a lens slower when close focusing?

I've heard that focal length of some lenses will become noticeably longer when focusing to a close distance, an effect called "focus breathing". Since f-number is focal length divided by diameter of ...
4
votes
3answers
266 views

Why do macro lenses have such recessed front elements?

This is a 90mm Tamron SP Di macro lens. Like other macro lenses in this focal range I've seen, it has a deeply recessed front element — more than 1.5", and that's without the optional lens ...
31
votes
3answers
18k 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 ...
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 ...
2
votes
1answer
175 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 ...