Questions tagged [calculations]

Photographic math — equations, formulas, algorithms related to making or processing images.

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3
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1answer
2k views

How do I calculate the maximum aperture at each focal length on a 35-200mm lens

I am looking for the linear maximum aperture of a 35-200mm 3.5/4.5 Nikon manual focus lens. I already know the max & min of the 35 & 200mm it's the 50, 70,105, & 135 that I am interested ...
3
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1answer
170 views

Why is the field of view of my lens narrower than my calculations show it should be?

The field of view of the Panasonic GH4 Micro Four Thirds camera with a 12mm lens is 84°. At a height of 120m, pointing straight down, I should be able to see 216m1 of ground across the diagonal of ...
0
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1answer
227 views

How can I calculate settings for manual flash to reduce trial and error? [duplicate]

I have two Yongnuo 560-III flashes that I have been using for a while, In order to get good results I am having to do a lot of trial and error. Adjusting power, zoom, moving them around etc. Is there ...
0
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1answer
1k views

How do I find the focal length that will fit a poster in the frame from across the room?

If suppose I want to take a photograph of a poster on the wall of the room, so I can't back away any farther than 5.0m to take the shot(max dist of the room). The poster is 0.80m wide and 1.2m tall, ...
1
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4answers
561 views

Does the crop factor affect the field of view (FOV)? [duplicate]

I'm working on smartphone cameras. I want calculate Field Of View of different smartphone cameras using the formula : FOV = 2 arctan(SensorSize/2f) where: f is the focal length sensor size is the ...
3
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1answer
519 views

Why isn't the size of an object in macro image exactly proportional to the ratio of the focal length and distance in front of that?

Using a Canon 550D with a EF 100mm f/2.8 Macro USM lens, I can make a 1:1 macro photo at shortest film plane to subject distance of 310 mm, thus getting 22 mm of a scale on the APS-C sensor, which is ...
4
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3answers
398 views

How to estimate the minimum magnification to capture features of a certain size?

What is the correct way to estimate the minimum magnification (maximum subject distance) at which features of a certain size are resolved? My thinking is that given a system capable of resolving a ...
3
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1answer
1k views

How to calculate the correct focal length needed for a subject of a given size and distance?

I need to purchase my first ever lens. So far I've only used lenses that were built into a camera. This specific lens is for the BlackMagic Deign Pocket Cinema Camera (a video only camera, but one ...
2
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2answers
163 views

Invariants in subject size and depth of field? [duplicate]

I was curious if I could cheat my way around having to focus stack an object by using different lenses. Playing with the Depth of Field calculator I noticed something interesting: No matter what ...
1
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1answer
261 views

Where can I find tables of common shutter speed and aperture values? [duplicate]

I'm working on image processing software (mind that I'm a programmer and when talking about photography, I'm "tabula almost rasa"). In this software, I'm using a RAW decoder that returns a data ...
1
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1answer
471 views

calculate the 1/x format of shutter speed from given floating point value

How to calculate the x in 1/x format when all i got is decimal floating point representation of the shutter speed ( for example 0.0101316 and possibly other data in exif )?
2
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1answer
759 views

Using a set formula to measure distance in a photo but the answers are coming out much smaller than expected?

I am using the formula distance to object (mm) = focal length (mm) * real height of the object (mm) * image height (pixels) --------------------------------------------------------------...
4
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6answers
1k views

Why don't cameras provide you with DOF information?

The viewfinder is usually not 100% accurate in representing the final image you will get and I've lost a few shots while using a too narrow DOF. I would imagine that cameras, knowing the focal length, ...
11
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1answer
9k views

How to calculate the optimal pinhole size?

As far as I've understood, optimal diameter for pinhole size is calculated by formula where d - the optimal diameter for pinhole c - constant f - focal length (distance between pinhole and ...
-1
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3answers
2k views

At what distance from the lens will the image be in focus given a subject distance and focal length? [closed]

I've been trying to figure this one out for more than an hour now and I have no idea how to calculate this... You capture a picture of a tree which is standing 3m away from the camera. The focal ...
-1
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1answer
4k 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 ...
4
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2answers
4k views

How do I calculate equivalent focal length from field of view?

I'm working with zone sieve and zone plate photography. Zone sieve/plate is similar to pinhole photography but it can give a softer, dreamier, look. This is a zone sieve photo I've taken: Zone sieve/...
1
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3answers
912 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 ...
4
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1answer
483 views

Lens f-number and speed on adapted lenses

A lens has a focal length, and its entrance pupil has a diameter. The ratio of these is an f-number. The size of the entrance pupil is limited by the size of the front element, and we describe lenses ...
2
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5answers
8k views

is the Nikon 35mm f/1.8 worth it after i have the kit lenses? [duplicate]

I have a Nikon DX (D5100) camera with the two most basic kit lenses: 18-55mm f/3.5-5.6 VR and 55-200mm f/4-5.6 VR. These two lenses cover lots of scenarios, but I'm starting to believe there is more ...
3
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3answers
14k views

Calculate object size when I have physical pixel size

How do I calculate the object size when I have focal length = 25mm distance to object = 700mm CCDs pixel size = 4,4µm ? My camera is this one. Appreciated! Edit: Could this work: real height = (...
6
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5answers
1k views

Is rotation an intrinsic lossy operation (for angles not multiple of 90 degrees)?

mattdm's statement "that blur is largely reversible if you do the exact same thing in reverse" raised the question in my mind. The rotation is a geometric transformation of the image that consist of a ...
2
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3answers
8k views

What is the diameter of the lens' aperture in mm terms?

I'm planning to create a customized aperture effect. Like this one in the Photo. I'll be doing a DIY customized aperture that will be attached to the filter. My lens' widest aperture is F/1.8 and ...
4
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2answers
6k 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 ...
1
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1answer
1k views

How does the depth of field with 50mm f/1.4 compare to 85mm f/1.8 with the same framing? [duplicate]

Possible Duplicate: Is there a formula to calculate DOF? Is there an easy way to establish, on paper, which of these two lenses, shot wide open and with the same subject size in frame, would ...
7
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3answers
2k views

How much distance should one move so that a shot that can be framed at xx mm be framed at yy mm?

Is there a website / app that will tell you approximately how much distance a person should move so that they are able to frame the same shot at different focal lengths? Say for example, I'm using ...
1
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3answers
899 views

How to get focal length from a camera specification which gives a value like “4.5-22.5”?

I am using a Sony W520 camera. The specifications mention Focal Length (f= mm) 4.5-22.5. What number should I take? The lower value or the higher? And if not both of them, then how to calculate actual ...
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1answer
3k views

How to calculate object's height in pixels from an image? [duplicate]

Possible Duplicate: Calculate object size when I have physical pixel size I am working on the following formula to calculate distance of object from camera: distance to object (mm) = focal ...
5
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1answer
19k views

How do I find a camera's focal length in pixels?

I am working on camera pose estimation. For this, I need the focal length of my smartphone camera in pixels. (My phone is HTC Wildfire S, with Android 2.3).
3
votes
1answer
476 views

How to understand the definition of dynamic range?

I have the following formula: DR=(1.4L_Sat G_i)/N_D where DR is the dynamic range; L_sat is the luminance at the “margin level”,70.1% of the maximum recordable (saturation)luminance(yes,L_sat is ...
6
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1answer
2k views

How can I calculate the change an extension tube makes to the maximum magnification of a lens? [duplicate]

Possible Duplicate: How can I calculate what the effect of an extension tube will be? My understanding is that extension tubes increase the magnification of lenses by reducing their minimum ...
3
votes
2answers
781 views

How to calculate object size dependent on distance?

I shot some images for use in a blog post. With the closeups, I ran into the problem of too low depth of field. Because I only need them for the web, I think that the easiest way to solve it would be ...
4
votes
1answer
268 views

Effect to reduce width of photo without cropping or stretching

I saw a documentary a few years ago (about 5) demonstrating a photographic manipulation formula, which can reduce the width of an image, without stretching, or cropping. It would do this by ...
2
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3answers
1k views

Is there a linear relationship between shutter speed and speed of subject to freeze motion?

Is there a calculation that I can do that will calculate the required shutter speed if I know the speed of my subject and want to get a crisp image e.g. freeze motion? For example if I go to a car ...
2
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2answers
785 views

Why are the area of aperture, focal length, and amount of light specified in these terms?

So I'm looking at the wikipedia article on Aperture, and I'm a bit confused. I understand aperture to be the diameter of the hole that lets light in. In the article, someone states that The ...
2
votes
1answer
217 views

What is the the product of two Fast Fourier Transfoms?

I am reading a book about image processing. I have found mention of a method for processing images. It is said that a special effect could be reached when we multiply two results of the Fast Fourier ...
2
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1answer
485 views

How much does extending affect range of focusing distances?

It's well known that moving a lens away from imaging surface will decrease both minimum and maximum focusing distance. There are times when it would be good to know how much those distances will ...
12
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3answers
4k views

What is the formula for percent of frame filled at a specific distance and focal length?

I am thinking about buying a new lens specifically to take photos of distant targets (birds, bears, etc). I currently own the Canon 70-300 IS USM, which is a nice lens, but I find that if I want to ...
0
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2answers
214 views

Correct conversion formula for photos to NTSC?

Working on some scholastic sports mutlimedia pieces, finished project to go on DVD. Last season (the one the got all the parents stoked) I didn't do conversions, thinking they would just go on ...