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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.

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1answer
73 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
73 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 ...
4
votes
3answers
728 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 ...
5
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0answers
66 views

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

This answer to another question of mine linked to an interesting article: High-Quality Computational Imaging Through Simple Lenses. It purposes the use of simple optics and computational photography ...
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2answers
379 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
78 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 ...
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3answers
225 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? ...
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3answers
307 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) ...
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1answer
79 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 ...
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0answers
140 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
118 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 ...
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2answers
153 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
180 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
181 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 ...
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0answers
34 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 ...
3
votes
3answers
171 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 ...
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2answers
126 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.
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2answers
357 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
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1answer
62 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
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2answers
133 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
2
votes
3answers
513 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 ...
3
votes
1answer
140 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 ...
4
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1answer
95 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 ...
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4answers
1k views

What is the most versatile lens for the Sony NEX-6? [closed]

I received a Sony NEX-6 body (no-lens) over the holidays this year and I am looking to find the right lens to match. I am searching for the most versatile lens available for this camera. In other ...
5
votes
1answer
760 views

What makes the Zeiss Otus 1.4/55 so special?

The new Zeiss Otus 55mm f/1.4 is nearly $4000. With faster lenses from Canon (50mm f/1.2L) with autofocus, why is the zeiss lens more than twice that of the Canon counterpart?
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1answer
92 views

Optical focal length [duplicate]

i have a quick question. We have a machine which has a camera mounted above a board at 75cm. The cameras ability to focus on an object at 0 zoom is 1cm, and all full zoom 120cm. The zoom is build ...
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1answer
281 views

Size of the entrance pupil vs size of the aperture

I understand that the entrance pupil is the image of the aperture as seen from the front of the lens. However, is the size of the entrance pupil the same as the size of the effective aperture? In ...
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3answers
212 views

Can I estimate the light gathering power of a lens by measuring size of entrance pupil?

Supposing I have an unknown lens of which I don't know f/# and focal length. I want to estimate the total amount of light that my lens can collect which, I believe, is given by the solid angle that my ...
2
votes
1answer
131 views

What lens is needed to change the minimal focus distance length of my camera?

Here is my problem, I Have a scientific camera, a Sony Block FCB-EH6500, which has an automatic focus. The minimum focus distance is 1 cm when completely zoomed out and 120 cm when fully zoomed in. ...
2
votes
1answer
284 views

How do anamorphic lenses produce lens flare “streaks”?

For example: What contributes to this streaking? Why doesn't spherical lenses have this effect? How is it used in photography?
0
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1answer
115 views

How do focal distance reductors affect image quality?

I have a bunch of lovely old full frame K mount lenses (like the 50mm f1.2 and the 135mm f2.5) and the idea of using them in a proper mirrorless body (I have the K-01 and that's a hell of a brick) ...
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1answer
161 views

What's the difference between a diopter and an extension tube?

It seems both allow close up shots of a subject but what are the differences both physically and in use cases?
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1answer
67 views

Should a fisheye converter be sharp when I look through it directly?

I bought a fisheye converter some days ago. Now, I am unsure if such a converter should create a clear image if I look with my eye straight through it. I found a video on youtube with the hint that ...
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6answers
711 views

What lens characteristics contribute to attractive lens flare?

Some lenses give really harsh and unwanted flares. Some gives beautiful flares that add depth to an image. What's the science behind this?
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2answers
317 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 ...
6
votes
1answer
150 views

What kind of mirror in a mirror lens?

A normal mirror, that we see for example in an elevator, is a glass sheet with thin metal coating on the backside, so light reflecting from the metal surface goes first thru the glass. Metal mirror ...
4
votes
2answers
530 views

How can I get the image/sensor dimensions in mm to get Circle of Confusion from EXIF?

I need to get calculate some formulas based on Circle of Confusion and/or image dimensions (diagonal) in millimeters based on EXIF data only. IOW, I cannot say "this photo was shot with Canon 5D3 ...
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1answer
427 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 ...
3
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0answers
147 views

Is this a Fata Morgana? [closed]

I took this photo. Above the horizon there is a thick line that looks like a cloud, but it surely isn't. Is this a Fata Morgana? What do you think? The Image
11
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4answers
579 views

Why aren't lenses designed with extra large apertures for autofocus beyond what's used for imaging?

Historically, designing large-aperture lenses has been difficult because correcting the optical aberrations that arise from large apertures requires complex designs and very large amounts of glass. ...
4
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3answers
387 views

What does it mean that a lens is x millimeters?

Every lens has different focal length in terms of millimeter so if I have a 100mm lens, what does that refer to? Does it mean the length of the lens itself is going to be 4 inches long, or does this ...
4
votes
1answer
106 views

Why do focusing aids darken when not looked at directly?

Many users of (D)SLRs equipped with a split image rangefinder or, to a lesser extent, with microprisms will notice how they have a tendency to appear dark in less than optimal conditions, such as ...
3
votes
2answers
443 views

What's the difference between real and effective aperture?

I understand that the simple idea that f-stop is focal length divided by aperture really applies to a simple single-glass lens, not the compound lens systems used to provide good image quality in ...
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vote
2answers
333 views

What does it mean for a telecentric lens to be focused to infinity?

I have a question about a telecentric lens Ive been studying (for physics research!) and was wondering if you guys could help clear some cobwebs in my head. For starters, I am simplifying the TC lens ...
19
votes
2answers
447 views

How do graduated ND filters actually work?

My question stems from the fact that the surface of the filter is completely out of focus. My understanding is that light from any one point of the subject hits the lens all over... some of it ...
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5answers
647 views

Why not have the diaphragm in camera body instead of the lens?

Why is the diaphragm to control the amount of light entering the camera typically in the lens and not the camera body itself?
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1answer
129 views

Does lens focus affect the appearance of sensor dust?

I know that aperture affects the appearance of dust on a camera's sensor (or, technically, the filter in front of the sensor), but does focus matter at all? Since the dust is behind the lens, I ...
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2answers
762 views

Does a specific f number across all lenses denote same amount of light?

When we say a light source emits 1500 lumens of light, it does not really matter if the light source is incandescent, CFL, diode etc. Similarly, when I say f/1.8 can I assume that all lenses pass the ...
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2answers
183 views

Why do the Nikkor non-AI 135mm vs 50mm f/1.8 work differently when I look directly through the lens?

I recently purchased an old Nikkor 135 f/2.8 non-AI lens. Beautiful lens, but the closest focal distance is about five feet. I noticed that it will 'focus' at about 4 inches as well. If I hold the ...
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2answers
654 views

Why does calculated distance of an object in an image vary when zooming?

I would like to calculate the distance of an object from my camera, so i used the formula given in this question and I got a very good answer, but I've found that when I zoom and take the picture and ...