Road Train !!!!!!!!!!

by Russell McMahon

submit your photo


Hall of Fame
View past winners from this year

Please participate in Meta
and help us grow.

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

learn more… | top users | synonyms

2
votes
4answers
124 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 ...
2
votes
0answers
116 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 ...
0
votes
1answer
65 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
votes
5answers
1k 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 ...
4
votes
3answers
748 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 ...
5
votes
0answers
80 views

Can the method from the paper “High-Quality Computational Imaging Through Simple Lenses” compete with conventiona lenses?

This answer to another question of mine linked to an interesting article: High-Quality Computational Imaging Through Simple Lenses. It purposes the use of simple optics and computational photography ...
2
votes
3answers
185 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?
3
votes
1answer
115 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 ...
22
votes
2answers
2k 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 ...
4
votes
2answers
330 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 ...
24
votes
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
votes
2answers
114 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 ...
19
votes
4answers
9k 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 ...
0
votes
1answer
113 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 ...
3
votes
3answers
188 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 ...
4
votes
1answer
240 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 ...
8
votes
2answers
531 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, ...
4
votes
1answer
97 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 ...
0
votes
2answers
197 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 ...
2
votes
4answers
2k 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 ...
7
votes
2answers
928 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?
12
votes
6answers
730 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
votes
3answers
809 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?
5
votes
1answer
785 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?
4
votes
1answer
451 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, ...
5
votes
2answers
488 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 ...
0
votes
2answers
213 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 ...
14
votes
5answers
3k 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
115 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 ...
7
votes
1answer
205 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, ...
19
votes
3answers
2k 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 ...
3
votes
2answers
120 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!
8
votes
1answer
165 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
312 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
482 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
145 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 ...
8
votes
3answers
594 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
278 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
votes
1answer
239 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
votes
1answer
63 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 ...
2
votes
4answers
747 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
votes
2answers
260 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 ...
7
votes
1answer
458 views

What is the difference between microcontrast and sharpness?

I keep hearing the internet talk of this micro contrast from the famous Zeiss lenses. What is it? Is it the same as sharpness? And if so, why is it called differently for Zeiss? Does anyone have any ...
11
votes
4answers
591 views

Why aren't lenses designed with extra large apertures for autofocus beyond what's used for imaging?

Historically, designing large-aperture lenses has been difficult because correcting the optical aberrations that arise from large apertures requires complex designs and very large amounts of glass. ...
11
votes
6answers
1k views

Do lenses lose sharpness when they age?

I was reading this answer where it mentions, "..it's a lens that can lose sharpness as it ages.." and was wondering if this is true and if yes, true for all lenses. Reasons as to why this happens and ...
5
votes
1answer
375 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. ...
2
votes
2answers
892 views

Why are large aperture lenses so expensive? [duplicate]

Why are lenses with very large apertures so expensive? For example, generally speaking, there is a significant price difference between a f/1.8, f/1.4 and f/1.2 lens of the same focal length. Doesn't ...
7
votes
3answers
810 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 ...
5
votes
0answers
48 views

How does lens design affect the richness of color reproduction? [duplicate]

Comparing a kit zoom lens to a faster, 20-year-old prime it seems like the old lens produces richer, warmer color. I've noticed the same kind of comparisons elsewhere. What is the lens actually doing? ...
4
votes
4answers
248 views

How small can current SLRs get and still give comparable photo quality?

Let's take the full-frame Canon 5D as example. How small can this camera be and still give comparable picture quality? What are the design constraints? Besides the sensor, the body, can the lenses ...