# Questions tagged [calculations]

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

151 questions
Filter by
Sorted by
Tagged with
1k views

### Calculate camera tilt angle from 2D image [closed]

I want to calculate the camera's tilt angle from a photograph, without knowing anything about the camera (or lens). Suppose I can extrapolate the vanishing points (one-point or two-point perspective): ...
5k views

### How to automatically measure subject dimensions (width/height/distance) without physically measuring?

What methods are used for automatically measuring the dimensions (width/height/distance/etc.) of a subject without having to get in there with a measuring tape? I am just starting to get into ...
536 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 ...
84 views

### What's causing my camera to slow down AFTER the image was saved?

I tested my Nikon D800 with a SanDisk Ultra 64 GB 80 MB/s SD card. I have a device which measures time and is triggered by the green LED light on the back of my camera which indicates that it's ...
596 views

### Calculating exposure when using ND Filter during/after the sunset or sunrise

It is very simple to calculate the exposure time when using ND Filters when the light is constant. Long exposures captured during changing lighting conditions make it much more difficult to calculate ...
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 ...
7k views

### How to calculate the size of the image circle at infinity focus?

How can I determine the diameter of the image circle (i.e. the diagonal size of CCD required to fully utilise a telescope's optics) at near-infinity focus? I have looked around online and found this ...
2k views

### Which SS/F-stop table is the correct one?

While reading a book that was recognized as a good one by many readers, I found the following table: This means that any of these settings would each result in the same amount of light hitting the ...
9k 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 ...
2k views

### Why does EV increase as ISO increases?

From what I understand, the lower the EV value, the more exposed (bright) the image is. EV decreases as aperture decreases. More light gets in with lower apertures. EV decreases as shutter speed ...
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 ...
137 views

### Is the hyperfocal distance calculation outdated?

The hyperfocal distance H is calculated by H = (f^2)/(N*c)+f where f is the focal length, N the f-stop and c the circle of confusion limit. Lets assume we use a fullframe sensor. All those calculators ...
2k views

### What is 'sensor height?'

The accepted answer to the question, How do I calculate the distance of an object in a photo?, refers to sensor height. What is sensor height and how do find/calculate it in this context? I'm using a ...
4k views

### How do I get the right size image for a specific small photo frame?

I have a picture frame that is 2 1/2 x 3 1/2 inches. I would like to know what kind of dimensions, in pixels, I should use with my Nikon D3300 to make a photo for the frame?
11k 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 ...
832 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 ...
220 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 ...
244 views

### Does field of view change for different lens model for the same focal length?

I am using two lenses - Tamron 75-250mm F/3.8-4.5 Model 104A and AF-P DX NIKKOR 70-300mm. When shot with lenses set to 250mm of focal length, the field of view for the Tamron lens is greater than the ...
832 views

### How to measure distance of exit pupil to sensor plane

Is there an experimental way to determine the distance of the sensor plane to the exit pupil? (acuracy a few milimeters with distances between 10-70 mm) Why I want this In my lab I am working with a ...
13k views

### calculating aperture and shutter speed inversion [duplicate]

I'm taking a manual photography class, using my canon rebel t5. Any tips on how to calculate aperture and shutter speeds easily? (I know they have to be inverted). After I meter my photo (set at -0-)....
111 views

### DoF app: should I round the image format/width up or down?

The DoF app I have calls for the sensor width to be set. The specs for my Sony α33 say the image format is 23.4 x 15.6mm. Do I dial-in the 23.4 or the closest to it? If I must go slightly over/...
956 views

### How do you calculate the focal multiplier of a non-full frame camera?

I'm currently using a Sony RX100 Mark 3 camera and want to buy a Canon 6D + 24-105 F4 L lens from an online retailer, which is not in my country. (before continuing I'd like to state that there are ...
781 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) --------------------------------------------------------------...
6k views

### What's the difference between S LOG and V LOG [closed]

I know what logarithms are, what shooting RAW is, and how storing images logarithmically increases details in shadows. But what's the difference between "S log" and "V log"? I've also seen mention ...
165 views

### How do I interpret flashlight specs for light painting at a distance?

Context So I've seen light painting shots and I'd like to try it out sometime. I'm more interested in painting say parts of the landscape so they stand out during a long exposure. Question Is there ...
418 views

### Can I calculate my phone's sensor size from f-stop, focal length, max aperture, or other metadata? [duplicate]

Could I work out sensor size of my phone from these info: F-stop= f/2.6 , focal length = 3mm, max aperture = 2.8 and others info like: resolution unit, exposure time?
175 views

### How to calculate the precision/resolution of a camera

I know there are other questions about this but I couldn't find the answer I was looking for... I am developing a control system using a camera and I need to know theoretically the precision/...
14k views

### How to calculate the real size of an object from two photos in different types of perspective, knowing the dimensions of one of the objects?

How to calculate the real size of an object from two photos in different types of perspective, knowing the dimensions of one of the objects in these pictures? When I was in college, we did such ...
2k views

### I'm hoping to prove this distance to camera equation:

D = f*H/h where D = distance from lens to object (d = distance from lens to 35mm film) f = focal length H = height of object h = height of object's image on 35mm film I've seen some form of this ...
186 views

### How do I calculate the total exposure value of two light sources?

Assume that I'm taking the photo of a lamp in an outdoor cloudy day. The lamp itself has the luminance corresponding to 17EV. The environment has the illuminance corresponding to 14EV. What will be ...
165 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 ...
486 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 ...
1k views

### How to calculate the correct position for this inception style photo

I came across this post: How is this changing vertical perspective effect achieved? Let's say those pictures have been taken by a drone, how would you calculate the positions (latitude, longitude), ...
260 views

### Can we prove that the object is not tilted from photo(s)?

This is an image of Al-Masjid an-Nabawi. Can we from this image, or from combination of images available online say with a certain degree of confidence (prove?) that this red circled minaret is ...
5k views

### How to calculate stops of light lost from a teleconverter?

How would I be able to take the multiplication value of a teleconverter (1.7, 1.4, 2, etc) and find out how many stops of light are lost when using it just based on that number?
291 views

### Can I increase 35mm-equivalent focal length with both the crop factor and an extender?

I have a Canon EOS 7D Mark II (1.6x crop factor), and I have a Canon EF 100-400 IS USM. Working with just 400mm for the purposes of this question, my understanding is that my 35mm-equivalent focal ...
1k views

### Is it possible to calculate focal length of a picture taken with a zoom lens if you know the aperture?

I need focal length (for my IA homework), but I didn't know that in real world I would only get the aperture. Ok, my camera is an Olympus X-21, and manual says: Olympus lens: 6.3 to 18.9 mm, f/3.1 ...
2k views

### How do I know how much light will be needed for a given film speed, shutter speed, and aperture?

For a given film type, shutter speed and aperture, how do I calculate the light needed to get a good exposure? For example, if I use a f/8 aperture, an exposure time of 100 ms and a ISO 800-film (...
481 views

### How can I use a non-TTL lightmeter beyond its built-in ISO range?

Some introductory information first: I got into photography a few months ago and I have very basic knowledge on the matter so be patient - the answers may be obvious for you. The camera is Zenit 11 - ...
765 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 ...
1k views

### Is my distance/size math for macro photography correct?

I was comparing Panasonic lenses the other day, and I wanted to know about their macro capabilities. Obviously Panasonic lists the closest focusing distance, but this doesn't tell me much about the ...
5k views

### How do I convert focal length to maximum distance?

I would like to know whether there is any relation between focal length and distance. For example, what is the max distance I can shoot from a 55mm-300mm lens?
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 ...
376 views

### Calculating the “35mm equivalent” circle of confusion/DoF

I'm gonna introduce my concrete example, but I'd like to know how do do this calculation in general. Say I have a middle-format camera with film height 58mm and a 90mm/3.5 lens. What is the equivalent ...
425 views

### Why is the image plane at Z = f in pinhole camera models?

Can someone show me the mathematical interpretation of why the image plane is at Z = f in the pinhole camera model? I found a possibly useful formula in Wikipedia, as shown in the figure below: My ...
574 views

### angle of view and distance from subject calculation for a smartphone

I would like to calculate the angle of view of a photo taken by a smartphone, in order and estimate the distance from a subject of a specific size. Let's do calculation for a Samsung S7, which has a ...
95 views

### Proper method to measure the magnification of a reversed lens [duplicate]

I have a 50mm prime lens and a 18-55mm standard lens at my disposal. How do I measure the magnification of a reversed lens when used with a reverse mount. What are the factors that come into play to ...
574 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 )?
231 views

### DOF comparison between two lenses

Someone told me: To compare the amount of DOF of two lenses I just would need to calculate the size of the entrance pupil. The lens with the bigger entrance pupil has less DOF thus creates nicer ...
203 views

### How can the focal length for shake reduction be determined when the lens is mounted using a reverse lens adapter?

My camera (Sony A7RII) offers image stabilisation (SteadyShoot). I shoot macros using a 50mm and a 28mm Olympus lens reverse mounted with anadapter. What values should I enter in the menu to ...