Questions tagged [lens-design]

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

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1answer
123 views

Why is Auto on aperture rings near the smallest aperture?

This is something that has puzzled me for a while and it always seems counter-intuitive. When a lens has an aperture ring with an auto position (A), it is always (at least on 3 systems that I have ...
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0answers
117 views

What causes swirling in bokeh? [duplicate]

The East German antique lens, Zeiss Biotar 75mm, is famous for producing a swirling, water-like bokeh as illustrated in the photo below: What optical materials and/or design cause this effect, which ...
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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 ...
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2answers
1k views

Why did typical number of iris blades decrease from the 1950s to the 1970s and 80s?

I have in my collection a number of 1950s "silver" lenses, and they all have a high number of iris blades: 10, some even 12. On the other hand lenses from the end of manual focus era (late 1970s to ...
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2answers
477 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 ...
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3answers
2k 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 ...
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6answers
486 views

Why is there no lens that is perfect for any situation? [duplicate]

My friend was talking about the 28mm, 70mm, and 200mm Nikon primes that he considers to be the "holy trinity" of lenses. Another friend asked why not just make a single 28-200mm zoom lens instead? I ...
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9k 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 ...
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2answers
257 views

Do lens optics/formulas, of the same lens model number, get updated as it is being produced?

Context I've noticed that the Nikon 105/2.5 has a long history of having many different versions from Sonnar v Gauss design to coatings and different blade counts for the aperture. Most of these ...
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225 views

What are the technical limitations that prevent lens manufacturers from producing 70-300mm f2.8?

70-300 f2.8 lenses don't seem to exist. What are the reasons behind that?
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4k views

Are there any 24-70 2.8 lens with no length change in zooming?

I'm planning to buy a 24-70 f/2.8 lens for my Canon 7D. I need a lens that won't increase its length while zooming (like the Canon 70-200mm series). Is there such a lens in any brand?
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Why do some telephoto zoom lenses physically extend while others don't?

The kit lens that came with my canon is an 18-135mm lens, but I hardly ever use it because I prefer my prime lens (I know a lot more about prime lenses than zoom lenses). One of my friends has a 24-...
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561 views

Is there any rhyme or reason to the order of zoom and focus rings on lenses?

I have 3 zoom lenses, 2 Nikkors & a Tamron. AF-S NIKKOR 24-120mm f/4G ED VR AF-P DX NIKKOR 18-55mm f/3.5-5.6G VR [the kit lens] Tamron AF 70-300mm F/4-5.6 Di LD MACRO 1:2 All except the 24-...
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3k views

What is the highest (slowest) f-number in a produced lens?

Kind of what it says on the tin. There's plenty of questions on Photography.SE about the fastest lens out there, but let's go the other way - what's the highest (non-infinite) f-number on a production ...
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593 views

Is there a List of Canon EF Push/Pull zoom lenses?

Is there a list of all push/pull zooms that Canon has manufactured for the EF mount? I do know the following ones: EF 100-400mm f/4.5-5.6 L IS USM EF 28-300mm f/3.5-5.6 L IS USM EF 35-350mm f/3.5-5.6 ...
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2k 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 ...
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3k views

What are groups and elements in lenses?

I hear people talking about groups and elements in lenses, but I am not sure what they mean. Could someone please explain?
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2k views

Is a two-prime lens possible? E.g. 35mm and 50mm

I really like prime lenses for their simplicity, zooming with my feet. I prefer it to a zoom lens because of this simplicity. But I do carry both a 35mm and 50mm because I do two different things ...
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10k views

What does “Flat Field Focus” mean?

Looking at lenses, specifically sigma macro lenses, I noticed that it had a ""Flat Field" front lens element". What does this mean? And how is it different to the norm?
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1answer
259 views

Which lens coatings reduce internal reflection?

I've used the Pentax Super Takumar 50 f1.4 and love the lens but notices that in certain lightning situations I get a yellow blur in the shape of the a lens blade. Using my hand I can sometimes stop ...
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1answer
230 views

What would be the reason to not include VR/IS in a telephoto lens?

A recently released Nikkor AF-S 105mm f/1.4E ED doesn't have VR. It surprises me a lot. I understand that there is little interest in having VR/IS in fast 35mm or 50mm lenses, but here, we are talking ...
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1answer
399 views

Why do old-school catadioptric lenses have a fixed aperture?

Pretty much what it says on the tin. As far as I can tell, catadioptric telephoto lenses (operating on a similar principle to many telescopes; using mirrors rather than refraction) fell out of favour ...
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1answer
2k 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 ...
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3answers
291 views

What's the purpose of these notches where the front of the lens case meets the side?

Here's a close-up of a Leica DC Vario Summilux. Note where the arrow points. This part is not movable—it's just a part of the lens's casing structure. The side surface is crossed by the front surface ...
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1answer
415 views

Limits of camera lens capabilities [closed]

I read that the canon 35mm f/2 IS is the lowest aperture lens that also has IS. Is this because a stabilizer at any lower F-stop is not possible, or just because it is just currently outside of our ...
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5answers
3k views

Is there development in the world of lenses?

Now, I'm not an expert, so if this post makes you laugh, you're welcome. Still, as far as I know there are basically two components that determine the potential quality of a camera's photos: Sensor ...
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1k views

What are the advantages of Tamron SP 85mm f/1.8 over the Nikon 85mm f/1.8G?

What are the advantages of Tamron SP 85mm f/1.8 Di VC USD over the Nikon AF-S 85mm f/1.8G and why Nikon is about $200 cheaper than Tamron? They are both similar on the specs. except for elements/...
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74k 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 ...
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1k views

Why do modern aspherical lenses have so much coma?

The Nikon Noct 58mm f/1.2 from 1997 is famous for having excellent coma control wide open. Sources generally credit this to its being one of the first lenses that used an aspherical element, which had ...
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6k views

What is a pancake lens?

I've read about a "pancake lens" but don't really understand what that means. What the pros and cons of having a pancake vs. another type of lens? I'm thinking of getting a Panasonic Lumix DMC-GF1 ...
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1answer
600 views

Is there a difference in the image produced from a 50mm rangefinder or slr lens?

Particularly, I am interested in the performance on film for Canon leica thread mount (LTM) 50mm lenses versus their FL/FD SLR lenses, in aperture size 1.2/1.4/1.8. Their performance on full frame ...
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1answer
2k views

Why do zooms have small apertures even around 50mm?

A 50mm f/1.8 prime from one of the major manufacturers can easily be found for $200 or less, but zooms that include 50mm in their range always seem to have much smaller apertures even at 50mm until ...
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3answers
545 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 ...
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1answer
368 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?
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601 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 ...
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4answers
2k views

Why is my large format lens so much smaller (in length) than my 35mm-format lens?

In general I have found that as the focal length of 35mm (or APS-C) lenses increases, the physical length of the lens increases as well. However, my large format lens is much thinner than other 35mm ...
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2answers
287 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 mm....
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1answer
106 views

What are the (dis)advantages of moving the entire lens for focusing vs. only parts of it?

There's a lens adapter available that adapts Leica lenses to Sony mirrorless cameras. It's called TECHART PRO. The key feature is that it allows to use autofocus with the manual lenses. This works by ...
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2answers
187 views

How much have tele-prime lenses improved over the years?

Context I'm considering the Nikon 500mm f4 AIS P lens as a way to get longer reach that's better than my current setup Nikon 300mm f4 AF with 1.4x TC to get birds and related wildlife. I've heard ...
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5answers
2k views

Why are filters only added to the front of the lens and not the back, too (or even the camera)?

I see how some filters have to be attached to the front of the lens, because they require some amount of interaction, like a graduated neutral density or circular polariser filter. But what about the ...
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232 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 ...
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1answer
354 views

Nikon Lens: A (Auto-focus) vs. A/M (Auto-focus/Manual)

I have two lenses which are 18-140 VR and 50 1.8G. On the 18-140 VR I got a button showing A and M while on the 50 1.8 I got a button showing A/M and M. I understand that A is for auto-focus and M is ...
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9k 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 ...
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2k 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?
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1answer
497 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 ...
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4answers
883 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 ...
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2answers
132 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 ...
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3answers
7k 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 ...
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4answers
2k 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 ...
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4answers
1k 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, ...