Questions tagged [lens-design]

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

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27
votes
4answers
3k 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
2
votes
1answer
149 views

Are “moustache” distortions in rectilinear ultrawides the result of a fisheye+pincushion construction?

If I wanted to try and build an ultrawide, I guess I would try building a fisheye first, then try tearing the frame back into shape with a group that introduces pincushion distortion. The kind of "...
7
votes
3answers
4k views

What's the opposite of a fisheye lens?

A 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 ...
46
votes
7answers
10k 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 ...
3
votes
1answer
4k 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 ...
12
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4answers
3k views

Does a large mount diameter really allow design advantages for large aperture lenses?

To keep the conversation simple, please focus only on native lens design for the mount. So with the recent Nikon mirrorless announcement, Nikon has been touting the bigger mount. I am no expert in ...
3
votes
4answers
101 views

Do strongly vignetted parts of a lens imaging circle gain depth of field?

Usually, vignetting in a lens (when not caused by glass losses, intentional graded filters or sensor issues) is explained as being a consequence of the effective aperture being smaller in corner areas,...
10
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3answers
159 views

What useful information can one gain from a lens element diagram?

On many photo gear review sites, cutaway diagrams of lenses are featured which show the layout of the elements in each lens. Here's the style of diagram I'm talking about, taken from Nikon's website ...
0
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3answers
86 views

Protective shell for Nikon 200-500 f5.6 lens?

The Nikon 200-500 f/5.6 lens has a zoom mechanism that makes the lens physically longer or shorter depending on the zoom level, but is there an enclosure that will accommodate the lens across its ...
6
votes
3answers
964 views

What enables the Canon RF 70-200 f/2.8 to be much smaller than the EF version?

Canon announced the RF 70-200 f/2.8L in February 2019. This is notable for being much smaller than the equivalent EF lens, being perhaps two thirds of the length, yet maintaining the speed of the EF ...
1
vote
1answer
42 views

Are front lens focusing and unit focusing equivalent in triplet/tessar style lenses?

Some vintage tessar or triplet type lenses (eg such intended for viewfinder cameras) implement focusing by merely moving the front element or front cell. When adapting such lenses to other cameras, ...
2
votes
2answers
92 views

Is diffraction limited aperture independent of lens?

I have always understood diffraction limited aperture as a property of the camera and its sensor, not of the lens. The camera has a certain sensor size and a certain megapixel count, which together ...
9
votes
4answers
2k views

What is the advantage of a lens with a curved focal plane?

In this answer it is noted that: many lenses intended specifically for portraits or fisheye lenses, are designed to have a spherical field of focus What advantages does having a spherical (or ...
-2
votes
4answers
143 views

Why is zoom provided in Tokina 11-16mm?

I wonder what's the use of providing zoom in the Tokina 11-16mm. Why not make it an 11mm prime lens instead? It would contain less elements, so will produce sharper images. Also at such wide angle, ...
0
votes
3answers
154 views

Does a camera have to have a contiguous housing?

The lens group in this picture would have its own protective lens tubes like the one on a camera but one for each lens group. What would be an issue having a gap between the lens group and stray light ...
4
votes
1answer
123 views

Why do CCTV and pro camcorder lenses often have vignettes, and apertures that can be fully closed?

I noticed this on both CCTV and "TV lens" C-mount lenses. Is this for manual black level calibration, or protecting some early sensor or *icon tube style from wear, or entirely another reason? It ...
3
votes
2answers
293 views

Is there any problem with this camera not having a lens cover?

I am considering buying the Fujifilm FinePix XP140, shown here: https://www.fujifilm.com/products/digital_cameras/xp/finepix_xp140/. I notice that most other cameras either have some form of lid that ...
1
vote
1answer
177 views

How wide does the front element of a lens have to be, given the focal length and the aperture?

Clearly, a lens with focal length F and aperture 1/f has to be at least F/f mm wide. Maybe a little more to accommodate the angle of view. However, lenses tend to have wider front elements than F/f. ...
4
votes
3answers
155 views

How commonly do constant-aperture manual zooms actually influence the aperture mechanically when zooming?

I have seen a few examples of constant aperture zooms (eg a 28-100mm f/4 Ricoh.) in the secondhand markets where the aperture appears to be not fully open (visibly non-round hole) at some zoom ...
17
votes
2answers
2k 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 ...
5
votes
4answers
1k views

Variable focal length for macro lenses?

True macro lenses come in fixed focal length. Are there any macro lensens which have variable focal lengths? And please explain why yes or why not?
6
votes
1answer
2k views

Why is anamorphic bokeh oval shaped?

I understand that an anamorphic lens "stretches" an image when it is recorded, but when it's played back, it's "un-stretched" so that it looks normal. But with images shot with anamorphic lenses, ...
8
votes
5answers
15k views

Which Zeiss lenses are actually made in Germany?

Recently, I used a Zeiss Makro-Planar T* 2/100 ZE only to find a big "Made in Japan" marking on it. Which of their lenses are made in Germany, and does it matter if it's made there vs. Japan?
14
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6answers
4k 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?
37
votes
3answers
4k views

When you zoom in with a lens on an SLR why does the lens go in then out?

I guess this is more a question of optics than photography but I just got an SLR with a basic 18-55 lens. I noticed that when going from 18 to 55 or 55 to 18 the lens physically comes back in and ...
5
votes
2answers
16k views

What is the difference between the Canon 55-250 IS II and 55-250 IS STM lenses?

I am a beginner in DSLR, and would like to purchase another lens other than the kit lens (18-55mm STM) that came with my Rebel T5i/D700. After much googling, and reading of blogs, I have decided to ...
13
votes
2answers
920 views

How do apertures which seem too large to physically fit work? [duplicate]

A 400mm f4.0 lens is supposed to have a maximum aperture diameter of 10cm. Looking at such a lens they don't seem big enough to fit that kind of aperture including all the mechanics for control inside ...
8
votes
1answer
1k views

Why are so many kit-lenses parfocal if it's an expensive feature?

According to this answer, parfocal lenses (lenses that can zoom in/out without losing focus) are relatively rare and more expensive. However, the original poster's kit-lens is parfocal. Additionally,...
8
votes
4answers
774 views

What motivated lens makers to now use 1/3 f-stops rather than say 1/4 or 1/2 stops?

I've noticed that many older lens have just hard f-stops for lens (2, 2.8, etc). However, since the aperture wheel for some is continuous you can "stop" are some arbitrary point and shoot. From my ...
7
votes
1answer
164 views

1960s-1990s third party lenses - why was the “lowest tier” cheaper to make?

From a retrospective, it seems that there were a couple of mid-tier makers/importers like Vivitar, Sigma, Tamron, Soligor ... and that there was a plethora of small brands (for example, one brand ...
1
vote
2answers
129 views

How can a lens produce better (or worse) colors than another one?

So I was looking the Lomography Lomogon 32/2.5 Lens, which looks pretty cool. However in the copy they claim that it produces images with great color. Now if the lens glass is slightly tinted, then ...
49
votes
3answers
8k views

What image-quality 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
2answers
197 views

What would a 10-300 f/1.4 lens (such as for a spacecraft) look like?

My basic question is, what would a fast lens with a huge zoom range look like? This question has been asked and answered for photographers on the ground - the answer was basically (rightfully) "no ...
11
votes
2answers
1k views

What are the constructional differences between a macro and a regular lens?

I understand that to reduce minimum focusing distances, macro lens design must focus on maintaining certain distances between the lens and the sensor. However, is the placement of the lens and its ...
2
votes
1answer
71 views

Is ROHS environmental theater the reason some lenses are only available as manual focus versions?

Classic lens designs often used glasses containing lead, thorium, cadmium and similar dopants. These materials are rather taboo in what counts as electrical equipment and accessories in many ...
6
votes
2answers
1k views

50mm mirror lens. Does one exist?

I like the bokeh and limitations of mirror lenses. I however, also love my 50mm 1.4. Does a 50mm mirror lens exist? I searched but could not find one. If not 50mm what is the closest to 50mm one can ...
5
votes
4answers
3k views

Why we can't use telephoto lens for macro objects?

As I know the focal length of macro and tele lenses are the same, which is around 200mm. Now I wonder, why we can not use tele lens for macro photography? P.S: Both macro and tele lenses have a focal ...
3
votes
2answers
104 views

Are bokeh (ball) shapes a result of vignette or aperture action?

The effect of getting shaped out-of-focus highlights (bokeh balls) from both non-circular apertures inside the lens, and masks applied in front of it (where an external aperture would presumably also ...
5
votes
1answer
93 views

What kind of lenses with a “slightly different diffraction behaviour” were used in “large format photography in the 1980s”?

Referring to an interview with a lens expert (Krolop&Gerst Objektivreihe 17/32), discussing diffraction limits. "Es gibt ein paar Spezialobjektive die haben ein bisschen anderes Beugungsverhalten,...
2
votes
1answer
712 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 ...
1
vote
2answers
296 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 ...
0
votes
4answers
672 views

What is the relationship between lens diameter and exposure?

All of the online calculators for exposure, I have seen, factor in time, film speed, and aperture (which is a function of the iris diameter and the focal length of the lens). However I would have ...
1
vote
1answer
167 views

What is the difference between these lenses? [duplicate]

I was looking at Canon lenses and I saw that there were a lot of different 35mm f/1.4 lenses that varied greatly in price and I'd like to know why there is such a huge range of prices for a single ...
6
votes
2answers
279 views

What are the production cost breakdowns for lenses?

I am very curious to know what the breakdown is for lens production costs. This information is hard to come by, and I am unable to find any reliable sources. Obviously, I can't just email Canon to ...
-2
votes
2answers
135 views

Is there a universal “safe” torque to use on the focus and zoom rings of all cinema lenses?

Is there a single torque amount that can be used at which all focus rings on all lenses can be moved that will allow a stepper motor to move the focus ring to adjust focus of all lenses without ...
10
votes
3answers
407 views

How can I know if two lenses have interchangeable elements?

This simple question might have a not so simple answer, and I want to ask it about a single lense, but assume that would be off topic, because I'd basically be asking 'should I buy this to repair my ...
1
vote
3answers
3k 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 ...
10
votes
3answers
5k 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 ...
3
votes
4answers
454 views

Why are all the mirrorless full-frame 35mm f/1.4 lenses so big?

The Sony FE, Nikon Z and Canon R mounts all have flange distances shorter than the Leica M mount, yet Leica has the compact Summilux 35m f/1.4 design whereas the above's comparably speced lenses are ...
9
votes
4answers
603 views

Why do prime lenses have multiple lens elements?

If I look up the specifications of my 50 mm lens, it says that it has 8 lens elements, in 7 groups. Why is this, why not just a single lens element with a 50 mm focal distance?