New answers tagged terminology
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What your colleague meant, based on your description, was: Setting the white and black point of the image.
On an 8-bit grayscale image, you have 256 different values ranging from total black (0) to total white (255) and various shades of gray (values 1-254).
An image with content only in the ranges between e.g. 0 and 120 (under exposure) might feature "...
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Would this image be considered a low or high contrast image?
In my opinion it would be neither a high contrast nor a low contrast image, but one that is somewhere in between the two extremes. Of course how one defines "high contrast" or "low contrast" or "moderate contrast" can be fairly subjective.
A high contrast image tends to have a histogram with ...
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The word contrast as it relates to a picture is defined as the degree of difference in tonality.
To call it high or low requires context... generally that would be within the capabilities of recording/reproducing the scene. Using rough measurements/rounded in the LAB color space...
The right side has values that range from 0:35-60, the middle has values ...
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For me also middle and right part of the image are also high contrast.
Here is the histogram of the middle part:
Here is the histogram of the right part:
Of course the contrast is not so high as in the left part, but it is strong.
And the right side of the image is darker obviously. ALso you have there a mixture of colours when on the left side is ...
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It's not really a category, as such, but the large areas of your example images that are mostly uniform are referred to as negative space. That is, they are spaces that do not have distinguishing details in them in the way the smaller main subject of the image does.
If you search stock image sites for images with negative space, you'll likely get the kind ...
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In the jargon of optics an objective lens is the lens (can be compound) that is the first to receive the image-forming rays from an object being examined or imaged. This lens or lens group is often called the objective lens.
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Among "non-photographers" in English speaking countries, I would think that "lens" would be much more understandable than "objective". Pretty much anyone who understands the technical meaning of "objective" used in the context of an optical system would also understand what "lens" means. The obverse would not be the same case, not everyone who understands ...
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As I tech writer, I understand your concern.
"Lens" refers to a single optical element. A compound lens is a single optical element with multiple focal properties, such as a bifocal lens. An "objective" is an assembly of multiple lenses.
Any English speaker who has worked with microscopes and similar devices is probably aware of the term "objective."
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English language is particularly confusing regarding optical assemblies, especially in the context of photography...
"Lens" indeed refers to the whole group of lenses (interchangeable or not) attached to the camera ... in microscopy and astronomy, this would be more formally called an "objective" (describing the sum of glass parts that AREN'T part of the ...
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The f-number system is unique in that it is universal. In other words, any lens, on any camera, regardless of focal length or image size, when set to the same f-number, will return an identical exposure. Well, not exactly, but close enough for most every need. In cinematography, a T-stop is favored. This is an f-top that has been calibrated to take into ...
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Aperture f-numbers are near approximations. And the 1.4x increment is approximately equal to doubling of the aperture area.
I.e. a 25mm aperture diameter (entrance pupil) has an area of 490mm; and 1.4 x 25mm = 35mm with an area of 962mm... approximately double the area/light/exposure.
If the lens is 50mm in focal length (FL), the 25mm aperture would be f/...
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A similar aperture numbering system called the U.S. system (Uniform System) was used by the first Kodak cameras (until around 1920s). That system originated in England (1880s). Not 1, 2, 3, 4, but those stops were numbered 1, 2, 4, 8, etc, starting from todays f/4 equivalence. It was more useful than 1, 2, 3, 4 because it represented exposure increase ...
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What is the purpose ... for the existing convention?
Math. It's because in many equations regarding simple optics, the ratio N = ƒ/D (where N is the ƒ-number, and D is the lens (or more often precisely, entrance pupil) diameter) pops up a lot, or the use of the ratio simplifies the expression or understanding of the expression.
Example 1: The hyperfocal ...
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