Questions tagged [lens-design]

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

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2answers
210 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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2k 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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1answer
326 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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1k 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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1answer
367 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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3answers
2k 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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5answers
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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3answers
1k views

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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1answer
223 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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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 ...
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1answer
224 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
336 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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3answers
262 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
319 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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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 ...
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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 ...
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4answers
1k views

Why there are so few lenses with small minimum focus distance?

My superzoom compact camera Canon Powershot SX60 HS has advertised minimum (closest) focus distance of 0 cm, and many other compacts have this in a couple cm range. But for my micro four thirds ...
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2answers
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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2answers
955 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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1answer
5k views

What are STF lenses?

What are STF (smooth transition focus) lenses? How much do they differ from other fast lenses? What artistic techniques are done with them? For example Sony has an a-mount 135mm F2.8 [T4.5] STF. What ...
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1answer
492 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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2answers
1k views

I am getting a complete vignetting on my new canon 6D but only with the 18-270mm lens

I had been using the Tamron 18-270mm lens with my old canon rebel camera and it worked just fine; but now I have the canon 6D camera and when I use it with the same lens it comes out with a complete ...
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1answer
1k 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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4answers
2k views

How can I increase the flange focal distance (back focal length) of DSLR lens?

I am working on a custom setup where I am using a DSLR lens (Canon 50mm f/1.8) to project an image onto an image sensor (image plane). For my application, I require a very large distance between the ...
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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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1answer
92 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
173 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
1k 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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1answer
338 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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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 ...
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2answers
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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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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4answers
659 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
127 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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1answer
278 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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2answers
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
95 views

Does the type of lens adapter matter for manual focus?

Context I use a cheap adapter that has an Aperture Ring for the new Nikon G lens but also works for older lens as well. I use a Sony a6000 which has focus peaking and related. Question Assuming ...
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1answer
772 views

How do lenses focus? (and zoom?) [duplicate]

My understanding of focal length is that it is the distance from the lens to the sensor; in my observations: higher focal lengths make for longer lens. Then I started thinking about how a lens ...
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3answers
396 views

Why don't we have a single lens e.g. say a 18-200 f/1.2 lens for the SLR camera? [duplicate]

Right now we have multiple interchangeable lenses. So why don't we have a single lens, say a 18-200 f/1.2 lens? Are camera manufacturers deliberately avoiding that or it is that it is physically ...
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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 ...
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2answers
3k views

Are there any secrets in lens design?

Lens manufacturers usually share diagrams like this for their products. However, they conspicuously omit specifications that would allow one to completely analyze the optical system, like the power ...
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1answer
983 views

How is focus-breathing controlled in lens design?

Answers here note that minimizing focus-breathing is especially desirable for cine lenses, and that it is one of the common features of those higher-end lenses. How is it achieved? Also noteworthy ...
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2answers
4k views

Are there lenses that exhibit absolutely no focus breathing?

As noted here focus breathing can be problematic, especially for macro focus stacking. Are there lenses that exhibit absolutely no focus breathing? Is there some way to find lenses that minimize ...
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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 ...
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4answers
594 views

What lens designs are sharper than a pinhole lens but also allow for multi-month exposures?

I have a homemade pinhole camera (film) that I use for taking super long exposures (multiple months). And while the results are fun, I would like to improve the sharpness of the image. Is diffraction ...
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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 ...
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2answers
457 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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2answers
1k views

What is the importance of the back focal length of a lens?

What is the effect and importance of the back focal length of a lens? For instance, if I look at these two lenses by Ricoh, they have the same focal length and aperture, but their back focal lengths ...
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2answers
277 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
1k views

Nikon 50mm 1.8g vs 1.8d? [duplicate]

What are some pros and cons of each? I use a Nikon D600 and am looking for my 50mm. I shoot a lot of video, so a smooth manual control is important to me. Besides that, I am unsure of what exactly I ...