Questions tagged [lens-design]

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

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3
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2answers
255 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 ...
10
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2answers
122 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
141 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 ...
13
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2answers
914 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 ...
6
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3answers
494 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 ...
1
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1answer
116 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 "...
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2answers
101 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 ...
2
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1answer
69 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 ...
1
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1answer
153 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. ...
5
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4answers
2k 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 ...
0
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2answers
191 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 ...
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,...
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4answers
414 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 ...
3
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2answers
95 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 ...
6
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2answers
186 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 ...
7
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1answer
156 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 ...
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 ...
4
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1answer
85 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 ...
3
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4answers
340 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
452 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?
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4answers
206 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 ...
12
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4answers
2k 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 ...
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3answers
191 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 ...
12
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4answers
3k views

How do manufacturers get to high (83x) zoom levels on hybrid cameras?

Obviously the biggest hybrid zoom on the market (Nikon Coolpix P900 I think) does not range from actual 24 mm to 2 meters in physical length, but what kind of optical systems do manufacturers use to ...
3
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4answers
409 views

What tiny lens to shorten the focus on a tiny camera?

I'm trying to set up a tiny camera for a tiny science experiment. The camera is an OmniVision OVM6211: It's pretty much a 3mm cube, containing the image sensor and all the lenses. It has a 90º FOV ...
2
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1answer
423 views

What does “Di III” in a Tamron lens model name mean?

A Tamron "Di" (Digitally Integrated) lens is a lens optimized for digital cameras including those with 36x24mm 'full frame' sensors. A Tamron "Di II" (Digitally Integrated II) lens is a lens ...
6
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3answers
152 views

How does sensor size affect minimum front element size for a given f-stop and focal length?

Does the sensor size affect the needed size of the front element given a focal length and f-stop? My intuition tells me that a bigger image circle would require a bigger front element to maintain the ...
5
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3answers
273 views

Why would lens be much longer than its focal length?

I accidentally saw Nikon 17-35mm f/2.8 lens and noted that it is rather large for its focal length. Here's the first review of this lens search offered - looks like it's 107 millimeters long. Given ...
5
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4answers
304 views

A thin camera and a thin lens with a large glass element

After seeing these 3D designs, I was wondering if a camera that is thin could possibly have such a large piece of glass in the lens (given the lens piece doesn't expand when powered on). As far as I ...
4
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2answers
327 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 ...
1
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2answers
204 views

Why do we not see super zoom lenses starting in wide angle?

While a common zoom lens might be 24-70mm and there are super zooms with ranges like 24-240mm I have yet to find a lens that starts in ultra wide angle and goes up to normal focal range. For example a ...
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2answers
300 views

Why is the kit zoom lens for Olympus so much smaller than that for Nikon?

I am currently considering buying either an Olympus OM-D EM-10 mark ii or a Nikon D3400. As a beginner I thought I would stick to the kit lenses for a while, and have seen that the specs of both kit ...
2
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1answer
115 views

What focal length make compact lens design easiest?

What is the focal length where it is easiest to build compact lenses? I have seen, when looking for compact lenses for several systems, that they tend to be in the normal to moderate wide angle range....
-2
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2answers
125 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 ...
3
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2answers
11k 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 ...
6
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2answers
967 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 ...
2
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1answer
158 views

What type of lens element is this?

I pulled apart a microscope objective lens to clean it. I was using it to take photos and noticed they were coming out blurry/cloudy. Turns out the first two lens elements were "cemented" together. ...
6
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4answers
2k views

Why do lenses for larger sensors tend to have shallower angles?

Why do different (mirrorless) cameras + provided lenses all seem to end up with a 24 mm 35-mm-equivalent focal length? The fixed-lens Canon Powershot G5X has a 1" sensor (actually 8.80 mm high) with ...
1
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2answers
264 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 ...
1
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3answers
272 views

Is focal length internal or external? [duplicate]

I just wanted to check because I've encountered various distinctly different assertions. I was originally taught that focal length referred to the optimum distance from subject| ←→|lens, where ...
4
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1answer
380 views

Helios 44 M - knurled knob with red W or M marking - purpose?

Edit: question modified for future googlers after discovering it's an M not a W. I recently bought one of the many varieties of tricked-up Helios you can find on eBay - fake anamorphic bokeh & ...
1
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1answer
106 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 ...
1
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0answers
108 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 ...
0
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2answers
650 views

What does “Kit DFIN III” means in CANON EOS 750D?

I have search around for "Kit DFIN III", but didnot find any reference. What is the difference between CANON EOS 750D Kit DFIN III SLR 24.2 Megapixel with lens 18-55 mm f / 5.6, 7.7 cm Touchscreen, ...
7
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2answers
812 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 ...
0
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6answers
288 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 ...
7
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3answers
3k views

What's the opposite of a fisheye lens?

I fisheye lens is an extremely wide-angle lens that is purposely designed to have extreme barrel distortion. Is there such a thing as a lens purposely designed to have pincushion distortion? What ...
5
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2answers
253 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 ...
1
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2answers
208 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?
1
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3answers
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?