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by Bart Arondson

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Optics is the science of light, and in photography often refers more specifically to to the properties and construction of lenses or the technical aspects of light sensors.

learn more… | top users | synonyms (1)

7
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2answers
262 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 ...
19
votes
3answers
4k views

What makes a Carl Zeiss lens so special in a smartphone?

There are smartphones on the market that have a focus towards photography. Some are equipped with a Carl Zeiss lens. I have looked into Wikipedia, which tells me that they are a brand who produces ...
3
votes
4answers
156 views

How can the focal length of a lens be many times greater than the lens's physical length?

I bought a Tamron 16-300. Question is: how can it have a focal length 0f 300 mm when it is only about 30 mm long? Doesn't the lens have to be 300 mm from the sensing element?
9
votes
6answers
4k views

Technically, why is the out of focus area blurred more when using a bigger aperture?

I'm wondering, technically, why and how does the out of focus areas blur more when using a bigger aperture. I think it'd help a lot if I presented a problem that's been driving me nuts for a long ...
13
votes
3answers
418 views

What is the Leica look?

What is the Leica look that fans of the company claim is unique to them? What concrete differences are there that are most obvious to a layman?
4
votes
2answers
642 views

Why are large zoom ratio constant apertures lenses not generally available?

I know about 17-55 f2.8 and the likes of it, but I am talking about something say 18-135 f2.8. There exists 70-200mm f2.8 and the range (200-70 = 130mm) is much bigger than in 18-135. I am aware of ...
3
votes
4answers
1k views

Why Isn't This Photograph Pin Sharp?

I Have Been Trying Out My New Canon EF 24-70mm and I'm pretty underwhelmed by its sharpness. Here is a RAW file shot from a solid tripod on an (almost) windless day using a remote. Obviously it ...
6
votes
1answer
133 views

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

This answer to another question of mine linked to an interesting article: High-Quality Computational Imaging Through Simple Lenses. It proposes the use of simple optics and computational photography ...
1
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4answers
198 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 ...
39
votes
2answers
17k views

What is the difference between a pentaprism and a pentamirror?

Higher-end SLR cameras include a pentaprism to transmit the image from the lens to the viewfinder, whereas lower-end SLR cameras use a pentamirror to accomplish the same task. What are the ...
3
votes
4answers
413 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 ...
0
votes
0answers
42 views

Technical question about aperture and lens [duplicate]

F stop = focal length / iris diameter So for example, my Lumix 20mm pancake, f1.7, has iris diameter of 12mm at that f stop, correct? So if Panasonic wanted to make a faster lens, could they do it ...
0
votes
0answers
44 views

What defines camera's size? [duplicate]

Smartphone cameras are small while others are big. I know some functions like zoom can change physical size, etc. So, ignoring a zoom lens, what defines a camera lens? I want to get the general idea ...
0
votes
1answer
60 views

Pentax k-30: can i buy all lens not stabilized?

I'm interested to buy a Pentax K-30. I'm wondering : can I buy not stabilized optics because of body' stabilized sensor ? Is the overall image quality comparable to an optic with stabilizer (like ...
4
votes
1answer
72 views

maximum aperture consistent with the nikon F mount

In a related thread, it's been debated whether there is a hard limitation to maximum possible lens aperture ; it seems there is none. However, using the example of the nikon F mount, this technical ...
30
votes
3answers
13k views

What does the number of elements and groups in a lens mean?

All lens specifications include a statement of how many elements the lens contains, and in how many groups, for example: Nikon AF-S VR Zoom-NIKKOR 70-300 mm 1:4,5-5,6G: 17 elements in 12 groups (two ...
5
votes
2answers
1k views

Is it normal for focal length to change while focusing?

When I change the focus distance on my Pentax 55-300mm lens, the focal length appears to change. More specifically, the lens appears to zoom in as I focus towards the minimum focusing distance. This ...
6
votes
2answers
455 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 ...
19
votes
3answers
6k views

How does the human eye compare to modern cameras and lenses?

A goal in most photography is to present a scene which resembles what a person who had been there at that moment would have seen. Even when intentionally working outside of that, human vision is the ...
2
votes
1answer
108 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 ...
2
votes
4answers
132 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
3answers
959 views

What does “maximum aperture” mean in a camera spec? Where can I get the full aperture range?

I own a Canon S95, and am considering getting a newer model (e.g. Canon S110 or S120), and I'm comparing the specs. According to DPReview.com, the S95 has a maximum aperture of F2.0-F4.9, and the S110 ...
40
votes
6answers
12k views

Why do light sources appear as stars sometimes?

See for example this photo: From my experience, the longer the exposure the stronger can this effect be observed. Is this correct? Are there any other factors that influence the creation of these ...
0
votes
1answer
61 views

Is there an “optimal” background distance when striving for a minimally distracting background?

Let's assume a thin lens and an object O in focus at a distance of dO from the lens. Further, let's assume there's a large out-of-focus background object B at a distance of dB. Now, we know ...
4
votes
2answers
167 views

Use of DOF adapters in stills photography

The camcorder guys figured out long ago how you can get the shallow DOF of a larger sensor system (typically full frame) on a camcorder equipped with a much smaller sensor (typically 1/2.8") by doing ...
2
votes
1answer
106 views

How to find numerical aperture of lens

I need to find the precise collection cone angle of an arbitrary objective at an arbitrary (but known and finite) object-side focal length. This is typically given as the "numerical aperture", defined ...
44
votes
7answers
7k views

What is a “diffraction limit”?

I've seen the term used, but what is a "diffraction limit", when should I worry about it, and what undesirable effects are a result of it ?
4
votes
3answers
776 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 ...
1
vote
3answers
638 views

Why image at 400mm is LARGER THAN DOUBLE of image at 200mm? (according to lens formula)

Like most of us, I thought it was yes. Until I really look into the Lens Equation: (1/subject distance) + (1/image distance) = (1/focal length) ...
7
votes
2answers
611 views

What is the cause of this non-uniform bokeh effect?

A friend of mine is thinking of buying a used medium-format film TLR camera (a Mamiya C330), and he showed me some of the test shots he'd taken with it. I was struck by the curiously non-uniform ...
3
votes
1answer
101 views

Do lenses have focal planes or focal spheres/ellipsoids?

The title says it pretty much all. I'm asking this because I find myself always using the focus point in the center, and after I focused, I rotate my camera to make the framing right. However, if ...
0
votes
3answers
529 views

35mm vs 40mm: Does it matter?

I want to buy the lens Voigtlander Nokton 40mm F1.4, $449 Voigtlander Nokton 35mm F1.4, $629 I am asking, why the slightly difference in focal length, the price difference in so much as $180? ...
8
votes
3answers
5k views

What is the technical difference between focus and zooming?

This may look like a silly question but I don't know what the difference between zooming and focusing is. Zooming in will usually let me have fewer subjects in the scene while zooming out will allow ...
4
votes
2answers
399 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 ...
0
votes
1answer
86 views

Aperture and field of view - percepted by eye vs camera

I very well informed and I know about how aperture works and why is it not restricting field of view, but I somehow cannot get around the following: Aperture doesn't restrict field of view for the ...
25
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 ...
0
votes
0answers
187 views

How is it possible for bridge camera with 50x zoom to cost so little? [duplicate]

i state that i'm a completely beginner in the wonderful world of photography. Last year i bought a Fujifilm FinePix S2980 ...
-1
votes
1answer
125 views

Is it possible to make an image which is only photographable in black or white?

Not sure if this is the right forum to ask this. Here is what I'm looking for: Example: I have a color photo could be text could be an image What I would like: if someone photographs this ...
1
vote
2answers
214 views

How can I build an underwater camera housing?

I'm thinking about building simple waterproof housing for camera. I don't expect high quality I want to record some videos good enough to identify fish species, nothing more for now. My housing will ...
2
votes
1answer
242 views

What is the largest aperture on a commercially available lens? [duplicate]

Out of pure curiosity, what is the largest aperture, or lowest f-stop, a commercially available lens has. I have seen the 50mm prime lens from canon with 1.2, but not lower than that. What are the ...
3
votes
2answers
208 views

How to compare the speed of lenses taking transmission into account?

When comparing the speed of two lenses, you almost exclusively hear about the maximum aperture. This of course makes sense, since at a certain lighting condition, a larger aperture in general allows a ...
0
votes
0answers
35 views

What causes the rays surrounding strong lights? [duplicate]

I've noticed, especially in long-exposure city lights photos, that strong light sources are surrounded by rays. The number of rays seem to depend on the lens being used. What causes these rays and the ...
93
votes
7answers
7k views

What is bokeh, exactly?

I understand that "bokeh" refers to out-of-focus areas of an image — but there is obviously more to it than that. What does the term mean exactly? How well is bokeh really understood? Is it purely ...
0
votes
2answers
131 views

Why human eye doesn't exhibit aberrations?

Eye's optical system is composed of single lens and is capable of producing very sharp results, but if I use single lens (monocle) with my camera I'll get soft image.
1
vote
2answers
551 views

Does wide angle equivalent in crop sensor skew image?

I see many posts on both this forum and elsewhere the discuss the use of a wide angle on a crop sensor. For example, they discuss how at 14mm lens is 14mm on a 35mm film or full frame, but with a ...
0
votes
1answer
70 views

Exact specification of N1-CL1 Nikon Closeup lens

On nikon site (and everywhere else) I've been unable to find any exact specification of tne N1-CL1 filter lens -- only thing I need is to know the exact focal distance of this lens (or dioptres, or ...
2
votes
2answers
148 views

Huge distortion with the 16mm lens

Today I've tried my new lens, but the image was very distorted in the right side. Here's the image: Is this normal? (The building on the right is very skewed) Bigger image: link
5
votes
1answer
106 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 ...
3
votes
1answer
159 views

Why is the center of image smudged with magenta/white at a small aperture?

I took two pictures with a Nikon D300 and a 17-55mm f/2.8G lens. Both pictures have been taken at ISO 200, aperture f/22 and shutter speed 1/8s. I used a tripod. The only difference between the two ...
-1
votes
1answer
650 views

How to calculate the magnification factor of an object to its image?

I have an object of size 37.5um x 37.5um, and captured a 640 x 480 resolution image of the object with a CMOS sensor. I see that the object is around 200 x 200 pixels in the image. How do I calculate ...