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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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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 ?
18
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3answers
5k 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 ...
16
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1answer
2k views

What is the “Newton Effect”?

I was just chatting with a photographer friend of mine, and he mentioned wanting "anti-newton glass"... I didn't know what that was, so I did a google search. I quickly figured out that it was ...
30
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5answers
5k views

How do constant aperture lenses work?

Cheaper zoom lenses usually are faster at the wide end and slower at the long end (for example, the $150 Canon EF-S 18-55mm f/3.5-5.6). More expensive constant-aperture zoom lenses have the same ...
35
votes
4answers
10k 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 ...
18
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3answers
2k 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 ...
9
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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 ...
18
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12answers
13k 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 ...
92
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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 ...
28
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4answers
2k views

How does aperture work without “cropping” the image hitting the sensor?

I've been teaching myself the various settings in cameras and now have a much fuller understanding of how to use my camera effectively, but one thing is still bugging me. When the aperture size is ...
32
votes
2answers
2k views

How do I interpret an MTF Chart?

As part of how Canon (and other lens makers) give technical information about their lenses, they supply an MTF (Modulation Transfer Function) chart. How do I read and interpret what the chart is ...
12
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6answers
534 views

Does lens speed still increase meaningfully when the physical aperture is larger than the sensor size?

This question came to me this morning, thinking about 50mm lenses. I have the Pentax 50mm f/1.7 (manual) and it's a very nice lens, but would be considered (relatively) slow on 35mm film, and many ...
17
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5answers
1k views

How does a circular lens produce rectangular shots?

Is it something like the sensor captures a circular image and then what we get is the cropped version? Something like this: Or did I get it completely wrong?
10
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3answers
2k views

How many optical aberration types are there in lenses? And what are they?

Everyone hears something about chromatic aberration but are there any other types? What causes them?
12
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3answers
445 views

What is Chromatic Aberration?

What is Chromatic Aberration? Is it a physical part of the lens, or just an optical illusion?
20
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4answers
2k views

What is focal length and how does it affect my photos?

What is focal-length? Are focal-length and zoom synonymous? How does the focal length of a photo affect it?