Photography Stack Exchange
Photography Stack Exchange

Questions tagged [focal-length]

Focal length is the distance (measured in mm) between the surface of a lens and the focal point, when the lens is focussed at infinity. Smaller focal lengths indicate wide-angle lenses, larger focal lengths indicate a telephoto lens.

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Estimating focal length range required for shooting scenario

Is it possible to estimate (or calculate), in advance, the range of focal lengths you might need for shooting in a given scenario? For instance, suppose you will be going to the zoo (with your APS-C DSLR) and you want to pack light, and assuming…
seanmc
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Distance marking on a lens - flange distance or film plane?

Some lenses have distance/ hyperfocal markings - is that with reference to the flange (outer mount point of the lens where it meets the camera body) or the film/sensor plane?
ralph
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Retrofitting of an old image documentation system with a new camera

I am trying to retrofit an old laboratory gel documentation system (Kodak 2000r) with a new camera (the original is dead). I connected to system lens a Basler acA1300-200um but the image I got is from a much reduced field area that is way too much…
amolero
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Physics/Optics vs Photography definition of focal length

I've been searching for some confirmation regarding the difference in DEFINITION of Focal length between: Physics/Optics(Which in the simplest case uses a classical thin lens to define the focal length as the distance from the lens to the focal…
ayazasker
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Keeping two subjects in focus (depth of field)

What is the best way to get two subjects in focus in a portrait (sometimes not at the same distance from the lens)? Obviously, this is a question of depth of field, but I am curious what some of the best tips are to get a sharp image with multiple…
rmooney
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Photogrammetry - use nodal point or entrance pupil for distance calculation?

I'm trying to accurately measure the size of objects via photogrammetry. The objects are 1 to 2 feet from the front of the camera lens, so where I start measuring from makes a difference. I think the proper distance measurement is from either the…
nerdfever.com
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Given the provided Image taken at 50mm, what focal length would I need to get the 80% fo the rabbit to fill the frame?

Given the provided Image taken at 50mm, what focal length would I need to get the 80% fo the rabbit to fill the frame?
user92012
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how many f stops should I allow for a given change in focal length - ISO and shutter speed remaining constant?

There are charts that show me what how many stops in shutter speed or ISO to allow when, for example, using an ND filter but given that a longer focal length reduces light available is there a chart to tell me what allowance in F stop to make for a…
Gerald M
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Trade Off / compromise to zoom lenses with longer focal ranges

I'm new here- looking for a community of folks to learn from. My love for photography was sparked on my honeymoon in Iceland last year. Now I can't get enough. My question to you is- what's the trade off for zoom lenses with longer focal ranges?…
Kat.Flanagan
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How does the focal length help in capturing wider or narrower picture?

I have been trying to understand the science behind cameras and photography. I started with "camera obscura" and understood that * when rays of light are passed through a small hole (aperture) of a dark room (or box), the rays get inverted (upside…
Flying Gambit
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How much zoom is needed for a distance of 600 ft?

How much zoom is needed for a distance of 600ft?
Karen
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What's the full frame equvialance of this phone lens?

I took a photo with my phone, and here is the EXIF: F/2 4mm 1/14s ISO-1250 I searched on the Internet and found that the sensor is Sony IMX134, 1/4 inch. Then how to calculate the equivalent focal length of this lens? (The equivalent focal lens of…
Nick
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Do I get more detail from a shorter focal length by being physically closer?

Let’s say I want to shoot a static scene and have a free hand regarding the focal length. If I ignore the geometric distorion for a while, do I get some image quality advantage by shooting from a closer distance, using a shorter focal length? Is…
zoul
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Is maximum focal length of P1000 similar to 300mm kit lens provided with APS-C cameras?

Is maximum focal length of P1000 similar to 300mm kit lens provided with APS-C cameras? Either in terms of 35mm or 1/2.3(sensor size found in P1000) format.
bypass restrictions
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How to get a clear image of a distant subject?

i have to shoot a subject which is 300 meters far and i need the image as clear as a portrait i took by a 18-55mm lense. Which lense i can use?
user70134
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