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

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1answer
264 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
244 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
1k 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
169 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
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1answer
128 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
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2answers
221 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 ...
9
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2answers
538 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
410 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
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3answers
677 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
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1answer
87 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 ...
7
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1answer
186 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
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3answers
979 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 ...
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2answers
607 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 ...
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vote
3answers
233 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
4k 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 ...
3
votes
4answers
576 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
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2answers
443 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
306 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 ...
9
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2answers
2k 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
350 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 ...
1
vote
1answer
112 views

what is the barriers of making fast lenses? [duplicate]

I know there are lenses like f/0.7 However as a beginner I'm wondering what's the barrier of making ultra fast lenses like f/0.01 ? Also if lens manufacturers willing to make wide aperture lenses, ...
6
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5answers
2k views

What about lens construction influences bokeh?

I can understand how certain elements of a lens can correct an aberrations or make it sharper - but specifically, how do lens manufacturers influence the bokeh - the quality of the blur? There's a ...
5
votes
3answers
1k views

Why do circular fish eye lenses create circular images?

I'm trying to understand the physics of circular fish eye lenses. As far as I can see circular fish eye lenses create an circular image because the area of the sensor is larger than the projected ...
4
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3answers
463 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?
4
votes
1answer
212 views

What is the reason that the materials of the lens barrels changed from metal to plastic?

Most of my older lenses have a shell of metal instead of plastic that is common today on all lenses even the expensive ones (with the possible exception of expensive tele lenses). When I compare the ...
5
votes
2answers
852 views

What are the theoretical minimum and maximum apertures?

Is there such a thing as a maximum aperture that a lens can be open to? What about a minimum aperture that it can be closed to? Do these concepts even make any sense? Is there a lens with the ...
25
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3answers
2k 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 ...
3
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2answers
378 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 ...
20
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4answers
14k views

Why is the aperture ring removed from new Nikon lenses?

Maybe I'm wrong, but I notice that Nikon's newer lenses don't have an aperture ring. For example, an older AF 35 mm f/2D is now replaced by AF-S DX 35 mm f/1.8G, or AF 50 mm f/1.8D is replaced by a ...
1
vote
1answer
208 views

What's with these petal-shaped lens hoods? [duplicate]

In the last decade or so, I've seen more and more lens hoods for long lenses that aren't simply round in front. I was reminded of that by this answer, which shows the inside of a neatly packed camera ...
9
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2answers
2k views

Do cine lenses have any significant advantages for still photography?

A number of manufacturers, including Canon and Zeiss, make cine-optimised lenses for still photography mounts (e.g. EF). For reasons well-covered elsewhere, these lenses are stupendously expensive, ...
5
votes
1answer
218 views

Which lenses show focus shift?

Some lenses, because of a design that includes uncorrected spherical aberration, shift their plane of focus backwards as the aperture is narrowed. This is most apparent at close focusing distances and ...
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4answers
34k views

What is the difference between Nikkor D type and G type lenses?

I recently bought a Nikon D5100. And along with this camera, I got the AF-S DX NIKKOR 18-55mm f/3.5-5.6G VR lens as kit. It's "G" type lens, right? One of my friend suggested to buy a 50mm f/1.8D ...
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5answers
1k views

What lens characteristics contribute to attractive lens flare?

Some lenses give really harsh and unwanted flares. Some gives beautiful flares that add depth to an image. What's the science behind this?
3
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3answers
12k views

What is the relationship between “macro” and “telephoto” lenses? [duplicate]

Can anyone explain the difference between "macro" and "telephoto"? I know that a macro lens will give you a magnification of 1:1 but how does it differ from a telephoto lens?
4
votes
1answer
1k 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, ...
6
votes
2answers
751 views

Why are there no fast APS-C zooms beyond 55mm?

I am looking to add a longer lens to my current zoom (a Tamron 17-50) for my Nikon D300 (but I believe this question is relevant across aps-c lens manufacturers). There is just one currently in ...
17
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5answers
7k views

What's the difference between the Canon and Nikon lenses mounts?

I was wondering what, if any, are the technical differences between the two mounting systems. Does one auto focus faster? Can one hold more weight? Things along those lines that make them different. ...
3
votes
3answers
128 views

Suggestion for books tracing the evolution of photographic equipment [closed]

Could you please suggest a book that Tracks the evolution of photo equipment from inception to modern times Has diagrams and cutaways of equipment and mechanisms, including shutter and aperture ...
9
votes
1answer
433 views

Why do certain lenses increase angle of view upon close focus?

I recently picked up a superzoom lens, the Nikon 28-300mm. Although I got it primarily for its versatility, my intuition was that a lens that can do 300mm focal length at 50 cm, as indeed it can, ...
8
votes
1answer
236 views

What kind of mirror in a mirror lens?

A normal mirror, that we see for example in an elevator, is a glass sheet with thin metal coating on the backside, so light reflecting from the metal surface goes first thru the glass. Metal mirror ...
2
votes
3answers
627 views

Are polarizing filters as useful on normal lenses as they are on wide-angle lenses?

I have seen people using Polarizing filters on many wide angle lenses. Is it worth using a Polarizing Filter on a 40mm 2.8f STM Pancake lens or any other prime lens?
3
votes
2answers
1k views

What's the difference between real and effective aperture?

I understand that the simple idea that f-stop is focal length divided by aperture really applies to a simple single-glass lens, not the compound lens systems used to provide good image quality in ...
2
votes
1answer
411 views

Canon 40mm STM - The focus cannot be adjusted in manual mode

I bought a new Canon 40mm STM lens and in the Lens Manual it says The focus cannot be adjusted in manual mode. Does it mean that its harmful to rotate the focus ring when the focusing mode is ...
9
votes
3answers
746 views

Why are Zeiss lenses heavier and larger for Canon EF than Nikon F mounts?

We recently acquired specifications for all DSLR lenses by Carl Zeiss and almost always the Canon EF-mount version is larger and heavier than the Nikon F-mount version. The difference ranges from ...
5
votes
2answers
573 views

Why aren't more lenses white?

So high end Canon lenses are white. This is to reduce heat, correct? If so why is this something that only appears in really high end Canon lenses. I wouldn't think that painting a lens white ...
0
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1answer
636 views

What is the infinity lens by Jim Frazier? [duplicate]

I know who Jim Frazier is and what he has done, but I only have basic knowledge of his invention. Could someone please explain what he has done further?
0
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1answer
105 views

Can I remove the tiny amount of wiggle in the focus ring of my brand new lens?

I just purchased a Samyang 24mm T1.5 lens and the focus ring is not 100% solid and smooth, there is a tiny amount of give in the vertical direction (perpindicular to the horizontal direction the ring ...
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4answers
4k views

When should I turn off image stabilization? [duplicate]

I've read a bunch of the questions here about image stabilization, but I don't see any concrete examples/proof or references with regards to the benefits of turning off image stabilization. I've got ...
3
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2answers
412 views

Why is there no apparent relation between focal length and physical lens size?

Why is there no apparent relation between focal length and physical lens size? For example, the Nikkor 20mm lens has a physical length of 42.5mm! That's more than twice the focal length! And if you ...