Questions tagged [lens-design]

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

Filter by
Sorted by
Tagged with
1
vote
4answers
129 views

Decrease FF lens focal length for use on APS-C and still have it focus?

Need to convert very cheap vintage FF 50mm f/2.8 lens to work as 35mm lens for for APS-C, for having wider angle of view. Its kind of works by simply placing lens closer to camera sensor (without ...
1
vote
3answers
140 views

Does the focal length on cropped lenses include a crop factor? [duplicate]

I'd like to be certain about the focal length written on the cropped lenses, e.g. I have a Sony NEX-5N with the original OSS 18-55mm kit lens. Is it actually an 18 to 55mm focal length with no "...
2
votes
1answer
72 views

Is focus shift inherent in the Zeiss Sonnar lens designs (more so than other lens designs)

One of the common "criticisms" of the Zeiss ZM C-Sonnar 50 mm/1.5 is its pronounced focus shift. That got me curious if the similar-design Zeiss Sonnars for the Hasselblad V-system (e.g. 150 ...
0
votes
1answer
666 views

In general, should I expect better image quality from a 24-70mm f/2.8 lens than from a 24-105mm f/4 lens?

I'm in the market for a full frame EF-mount standard zoom lens, so I've been doing a lot of research about different 24‑70mm f/2.8 and 24‑105mm f/4 options. I understand the tradeoffs in terms of ...
1
vote
4answers
331 views

Why is there an air gap between lenses and digital sensors, as opposed to continuous glass-like higher refractive index?

Thinking about ultra-fast lenses (ƒ<1), it would seem useful to have a solid+liquid medium between lens and sensor. This wouldn't have been very practical (presumably) at the time of film, but with ...
4
votes
4answers
211 views

Seeming contradiction on wikipedia about rear nodal points and how the principal plane is related to focal length

There are two lines on the wikipedia pages for "cardinal points" and "focal length" that seem to contradict each other, and I would be extremely grateful if someone could explain ...
0
votes
2answers
478 views

Canon 18-55mm lens giving err01 after it fell down

Sometime back I accidentally dropped my canon EFS 18-55mm lens (open caps); I cleaned the contact areas and any kind of dirt I could see on it. After that it was a bit jittery whenever I zoomed, but ...
3
votes
2answers
277 views

How to use spacer rings to change the behaviour of the Nikon 35-70 f/2.8 lens

I recently bought a Nikon 35-70 mm f/2.8 lens with some scratches on the front element. I exchanged the front element with the element of an old lens I had lying around. Everything works fine, but now ...
0
votes
3answers
159 views

Is it possible to commission a custom lens that would significantly outperform stock lenses?

I know that to get better image quality often requires aspherical lenses, which are expensive to make, so at some point it becomes non-economical to have a lot of aspherical elements in a camera lens. ...
2
votes
3answers
130 views

Différence between a long lens design and a telephoto

I was looking at the Leitz Hektor and Ken Rockwell says "This is a conventional long lens design, not a telephoto. Its diaphragm sits right at 135mm from the image plane. The Nikkor lens shown ...
0
votes
1answer
105 views

Laowa 7,5 mm F2 Lightweight Micro 4/3 vs. Laowa 7,5 mm F2 Standard Micro 4/3

I am interested in buying a wide-angle lens. The Laowa 7.5mm F2 Micro 4/3 seems to be the best option for my purpose. I have found it in an online shop and was wondering why the lightweight version (...
5
votes
4answers
223 views

Why are flatbed-scanned images warped when compared to itself scanned & rotated 90 degrees?

This has been absolutely baffling me. I scanned an image both vertically and horizontally on the flatbed of my HP Color LaserJet Pro MFP M277dw using Windows Fax and Scan. I then used Gimp to rotate ...
-3
votes
2answers
472 views

What is the advantage to not use names, but only descriptions as unique identifier for lenses? [closed]

If I want to buy a new camera, I use its model number to look at review sites and videos, compare photos on photo websites e.g. flickr and search on price comparing websites and market places where I ...
2
votes
1answer
243 views

Are internal focusing primes actually uncompensated varifocal lenses?

If I shorten the focal length of a lens without taking any other measures, that will reduce the required flange distance for infinity focus - meaning that if the actual flange distance is not changed, ...
1
vote
2answers
239 views

What's the best choice of lens from an optics surplus shop to get a Stanhope Lens-like magnifying function?

I am looking to do some experiments with my cellphone and a lens, holding the lens in contact with my cellphone lens. I'm looking for a lens that has the shortest back focal length length possible, so ...
1
vote
3answers
476 views

Why are adapters for slightly too-short backfocus lens mounts not made with just a thick glass window instead of a lens element?

Infinity-correcting adapters tend to incorporate a weak teleconverter usually. It would appear that a thick, planar optical glass window is also capable of lengthening back focus - and would probably ...
0
votes
1answer
121 views

What is behind this symmetric coma like effect, and literally odd-ball bokeh, in a triplet lens?

The example picture, shot with a vintage triplet (Staeble Kata 45mm/f2.8, wide open, on APS-C, no further crop), shows a curious shape of coma-like cross pattern in the right- and leftmost sculptures -...
3
votes
4answers
127 views

Do strongly vignetted parts of a lens imaging circle gain depth of field?

Usually, vignetting in a lens (when not caused by glass losses, intentional graded filters or sensor issues) is explained as being a consequence of the effective aperture being smaller in corner areas,...
1
vote
3answers
258 views

Protective shell for Nikon 200-500 f5.6 lens?

The Nikon 200-500 f/5.6 lens has a zoom mechanism that makes the lens physically longer or shorter depending on the zoom level, but is there an enclosure that will accommodate the lens across its ...
2
votes
2answers
335 views

Is diffraction limited aperture independent of lens?

I have always understood diffraction limited aperture as a property of the camera and its sensor, not of the lens. The camera has a certain sensor size and a certain megapixel count, which together ...
1
vote
1answer
199 views

Are front lens focusing and unit focusing equivalent in triplet/tessar style lenses?

Some vintage tessar or triplet type lenses (eg such intended for viewfinder cameras) implement focusing by merely moving the front element or front cell. When adapting such lenses to other cameras, ...
-2
votes
4answers
154 views

Why is zoom provided in Tokina 11-16mm?

I wonder what's the use of providing zoom in the Tokina 11-16mm. Why not make it an 11mm prime lens instead? It would contain less elements, so will produce sharper images. Also at such wide angle, ...
0
votes
3answers
166 views

Does a camera have to have a contiguous housing?

The lens group in this picture would have its own protective lens tubes like the one on a camera but one for each lens group. What would be an issue having a gap between the lens group and stray light ...
3
votes
2answers
506 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
votes
3answers
241 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
votes
3answers
222 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
votes
2answers
969 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
votes
3answers
1k 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 ...
2
votes
1answer
158 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 "...
1
vote
2answers
297 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
votes
1answer
91 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
vote
1answer
383 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
votes
4answers
5k 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
votes
2answers
205 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
votes
1answer
138 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,...
1
vote
6answers
2k 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
votes
2answers
165 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 ...
7
votes
3answers
2k 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
votes
1answer
189 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 ...
10
votes
3answers
439 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
votes
1answer
155 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
votes
4answers
1k 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 ...
10
votes
4answers
1k 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?
1
vote
4answers
501 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
votes
3answers
5k 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 ...
1
vote
3answers
472 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
votes
4answers
5k 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
votes
4answers
1k 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
votes
1answer
3k 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
votes
3answers
218 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 ...

1
2 3 4 5 6