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

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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 ...
0
votes
1answer
812 views

Below which focal length are lenses considered to be wide angle?

Focal length is the only factor that decides whether a lens is described as being normal or wide angle. Below which focal length are lenses considered to be wide angle? Is this focal length the same ...
7
votes
2answers
2k views

Are all DSLR lenses made of glass?

This question is about lenses to "big" DSLRs, not system or compact cameras with interchangeable lens. Are all lenses made of glass in DSLR? And if not, is there a notable difference between: kit ...
1
vote
3answers
618 views

What does a megapixel designation on a lens actually mean?

I know that in a CMOS sensor the megapixels give you an idea of how many pixels are actually there to capture the light. In terms of a lens however, I cannot find any relation between the megapixels ...
1
vote
2answers
145 views

Does Apple make its own lenses for iPhone cameras?

Does Apple make its own lenses for iPhone cameras? Or, does it at least design them? If not, does it source from a lens maker like Zeiss, or a camera maker like Canon?
1
vote
1answer
178 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 ...
12
votes
3answers
1k views

How do zoom lenses restrict their widest aperture at the telephoto end?

Does the aperture ring lock the apertures beyond, say 5.6 at length lens's telephoto end? Does the lens introduce an obstacle to the aperture ring so the lens can't be opened anymore beyond the ...
34
votes
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 ...
4
votes
2answers
258 views

Is having a lens with vignetting a real world negative for portrait lenses?

After reading this answer for another post: I don't mind the vignetting as it actually improves the look of portraits however if you're doing astrophotography what's the point in a lens that's ...
4
votes
1answer
369 views

What is meant by 'centering quality'?

I'm reading lens reviews and I have encountered the term 'centering quality' a few times (e.g. http://www.photozone.de/sony_nex/720-sony50f18nex?start=1). What does this term mean? What are the ...
4
votes
4answers
155 views

Which focal length lens generally has the sharpest lens? 24, 35, 50 or 85?

Context I realize that the above four focal lengths lend to having a different perspective that make them all unique. It might be possible to use one as the other but that isn't always true with the ...
2
votes
2answers
50 views

Have lens/camera bodies been repairable by the consumer/user back in the day?

Context I've been skimming LensRental and related websites and I see most all modern lens are extremely complicated, intricate, expensive but they work, mostly. I see that with a7rII, there is an ...
1
vote
0answers
77 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?
22
votes
3answers
4k 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 ...
1
vote
4answers
596 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 ...
5
votes
4answers
450 views

How do manufacturers come up with focal lengths for lenses?

There are a lot of lenses for each camera, and I understand that each lens caters to a different use case, but my question is on how they arrive at the specific focal length numbers. For example, ...
2
votes
1answer
60 views

Does the type of lens adapter matter for manual focus?

Context I use a cheap adapter that has an Aperture Ring for the new Nikon G lens but also works for older lens as well. I use a Sony a6000 which has focus peaking and related. Question Assuming ...
33
votes
4answers
22k 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 ...
0
votes
1answer
132 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
168 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
595 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
votes
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
220 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
321 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
427 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
203 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
136 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
116 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
561 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
2k 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
158 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
273 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) ...
15
votes
4answers
29k 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 ...
29
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
112 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
522 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
188 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 ...
2
votes
2answers
201 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
730 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
115 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
250 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
236 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
220 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
976 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
163 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 ...
2
votes
1answer
124 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?