Questions tagged [lens-design]

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

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4answers
97 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, ...
45
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6answers
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 ...
0
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3answers
142 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
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1answer
116 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 ...
1
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1answer
130 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 "...
3
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2answers
266 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
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1answer
156 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. ...
10
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2answers
125 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 ...
4
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3answers
143 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 ...
16
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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
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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
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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
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5answers
14k 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
3k 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
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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 ...
6
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3answers
578 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 ...
4
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2answers
12k 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
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2answers
916 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
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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
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4answers
716 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
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1answer
158 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
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2answers
106 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
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3answers
7k 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
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2answers
192 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
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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
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1answer
70 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 ...
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 ...
6
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2answers
973 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
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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
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2answers
96 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
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2answers
76 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,...
9
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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
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1answer
674 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
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2answers
272 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
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4answers
466 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
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1answer
166 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 ...
2
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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 ...
6
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2answers
191 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
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2answers
127 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 ...
9
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3answers
403 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
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3answers
2k 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 ...
9
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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
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4answers
360 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
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4answers
476 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?
1
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4answers
223 views

Are all prime lenses designed so that the same DoF scale applies at any focusing distance? If so, why?

This question is about the mapping between the angular position of the focusing ring and the focusing distance. This mapping could be anything but the design of prime lenses seems to be such that a ...
4
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2answers
344 views

Where can I find a mechanical drawing of the Canon EF Mount?

This is my first question-post. First of all my final goal is to build a simple but functional objective. I was inspired by this video: DIY Camera Lens (I don't hope to make something so neat the ...
2
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3answers
469 views

Why not separate a tilt shift lens into two separate lenses?

When using a tilt shift lens I find myself using the two features of tilting and shifting for separate photos. If I want to control the depth of field such as in a portrait or macro shot I will tilt ...
4
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3answers
596 views

Why are phase detect lenses adapted onto contrast detect bodies so much slower?

The Sony A7 is able to adapt almost any type of auto-focus lens (Canon/Nikon/etc) and use autofocusing, but the auto-focusing is much slower than the same focal lengths native for the A7. Why would ...
8
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4answers
2k views

Why did manufacturers 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 DOF preview doesn't help that much ...
1
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3answers
209 views

What does the value of 'exit pupil' represent on a lens datasheet?

On this datasheet of the Kowa LM25HC lens I have access to, there is a number called exit pupil, which equals -57.9 mm. What does this number represent? This is not a question about what the exit ...