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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)

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1answer
105 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
116 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
154 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
165 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 ...
2
votes
3answers
256 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 ...
0
votes
0answers
33 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
140 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 ...
92
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
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2answers
121 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
228 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
51 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
123 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
4
votes
1answer
90 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
128 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
354 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 ...
0
votes
4answers
677 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 ...
18
votes
12answers
14k views

How does the lens diameter influence photo quality?

I have tested two different 50mm lenses in my camera. One was a Nikkor 50mm ∅52mm. The other one was a Sigma 50mm ∅72mm. I took some pictures with both lenses using the same setup for aperture and ...
12
votes
6answers
666 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?
5
votes
1answer
696 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?
0
votes
1answer
90 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 ...
0
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3answers
193 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 ...
1
vote
1answer
219 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 ...
6
votes
3answers
1k views

How does a short flange back distance improve image quality?

In the description for the new lens mount for their X-Pro series, Fujifilm says: 1: Specifically designed to maximize the mirrorless design of the body, the X-Mount has a short flange back ...
2
votes
1answer
127 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. ...
40
votes
7answers
5k 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 ?
2
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1answer
228 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
votes
1answer
110 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) ...
1
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2answers
136 views

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 ...
1
vote
1answer
152 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?
0
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1answer
65 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 ...
6
votes
1answer
145 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 ...
9
votes
2answers
7k views

What is the Chief Ray Angle (CRA)?

I want to select image sensors for a particular application. One term that I have come across regularly in their datasheets is the CRA. I was comparing 2 image sensors and although they were of ...
3
votes
2answers
356 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 ...
4
votes
2answers
378 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 ...
12
votes
2answers
2k views

Why are cine lenses so much more expensive?

For example, compare a cine lens like the Zeiss Compact Prime CP.2 50mm/T2.1 ($3,900) to a high-end DSLR lens like the Canon 50mm f/1.2L ($1418). Both are EF-mount, have the same focal length, and it ...
3
votes
0answers
146 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
votes
4answers
549 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. ...
7
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5answers
598 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?
16
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6answers
2k views

Can a smaller sensor's “crop factor” be used to calculate the exact increase in depth of field?

If APS-C and similar crop-sensor digital cameras have a focal length multiplying effect such that a 50mm lens has an apparent focal length closer to the field of view of an 80mm on a full frame ...
22
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2answers
3k views

What is a zone plate?

I was looking into alternative methods of photography and I happened upon something called a 'zone plate.' Three questions: What is a zone plate? How does it work? What can I do with it?
4
votes
3answers
364 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
104 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 ...
7
votes
3answers
610 views

What are ED elements?

I find that some lenses are indicated with the letters "ED", referring to some special type of lens element. What are ED elements, and what advantages do they bring? Note that this question isn't ...
11
votes
5answers
7k views

What is “infinity focus”?

I have been reading a bit about astrophotography and the term infinity focus keeps coming up. What is infinity focus and how do you set the camera to infinity focus?
27
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3answers
2k views

What does a hexagonal sun tell us about the camera lens/sensor?

In this picture, we see that the sun comes out as a hexagon. I am sure it is not arbitrary. What does the hexagon tell us about the instrument that captured the image?
11
votes
3answers
474 views

How does the D800E reverse the effect of an antialiasing filter by adding another filter?

According to http://mansurovs.com/nikon-d800-vs-d800e the D800E differs from the D800 in that one of the layers of the filter reverses the effect of the initial low-pass filter. How does this work? ...
1
vote
2answers
294 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 ...
46
votes
4answers
3k views

Why aren't all viewfinders 100%?

We often see that a manufacturer's high-end (D)SLR models offer a "100% viewfinder," which shows the entire exposed frame, and allows precise composition with regard to objects near the edge of the ...
19
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2answers
439 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 ...
9
votes
4answers
412 views

Why are some zoom lenses “soft” at either end of the focal length range?

As one reads about zoom lenses, a relatively common comment that comes up in reviews of some lenses (especially lower-priced lenses) is that the lens is not as sharp ("soft") at one or both ends of ...