# Questions tagged [calculations]

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

137 questions
Filter by
Sorted by
Tagged with
206 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 ...
173 views

### How to correctly calculate the Dynamic Range of an image

I'm trying to compare the dynamic range of a correctly exposed LDR picture with the dynamic range of the HDR image obtained with 3 LDR pictures. Right now I'm calculating the DR as: stops = log2(...
77 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 ...
2k views

### Why doesn't the focus distance at which my lens has magnification 1 match the formula?

From the Magnification Wikipedia page, I have the following equality: M = di/do = f/(do – f) = (di – f)/f with M the magnification, f the focal length, do the distance from the subject to the lens,...
801 views

### Why are my pictures blurry even though a DOF calculator shows everything should be in focus?

In theory, according to the DOF calculator, I can achieve infinity focus with my Sigma 10-20 at f/3.5 when focusing at a subject that's 2m away but when I put it to the test my pictures come out super ...
437 views

### How to calculate the max size of an image based on the canvas size?

How to calculate the maximum height or width of an image based on the canvas size or poster card size? example: image size is as below: height: 3648, width: 5472, and poster card size: 150 * 100 (W*...
272 views

### Shutter Speed from the Exif ShutterSpeedValue

Extracting Exif data from my photo (using python) among the other values I have: 'ShutterSpeedValue': (8643856, 1000000), 'ApertureValue': (1695994, 1000000) After some research, I found that the ...
1k views

### How to calculate focal reducer crop factor for APS-C to MFT?

As far as I can tell, the crop factor determines the size of the projected image circle and should match the ratio of sensor diameters (with standard mount forward / backward distance). My ...
153 views

### How do I calculate how high a camera needs to be to fit an object in the frame based on its field of view?

I'm doing a computer vision application related to snooker for my dissertation. In a section of my report, I’m talking about cameras and it would be good if I’m able to do the calculation stated above....
6k views

### Can a smaller sensor's “crop factor” be used to calculate the exact increase in depth of field?

If APS-C and similar crop-sensor digital cameras have a focal length multiplying effect such that a 50mm lens has an apparent focal length closer to the field of view of an 80mm on a full frame camera,...
3k views

### How do I calculate the number of stops between two shutter speeds?

What is the math equation to calculate the difference between two different shutter speeds in stops?
254 views

### What is the formula to calculate aperture (“diaphragme” in French)?

Let's say I have these data for my camera: t : Exposure time in seconds ("temps de pose" in French) C : Incident-light meter calibration constant ("constante lumière incidente" in French) S : ISO ...
160 views

### How to calculate the new focal length when usng a lens mount adapter

I'd like to know how to calculate the new focal length when using a lens adapter. Is there any formula? To be more specific: I need to attach my old lens (four third) to new micro four third system ...
185k views

### Is there a general formula for image size vs. print size?

What size images do I need for common print sizes, such as wallet size, 8x10, and 16x20? Is there a general formula? How could that size change if, for example, a 16x20 was printed on canvas rather ...
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 ...
119 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 ...
743 views

### Why I am getting different values for depth of field from calculators vs in-camera DoF preview?

When using depth of field and hyperfocal calculators, I get very different result versus the in-camera DoF preview of my Fujifilm X-M1. For example: With DOFMaster (or any other online calculator), ...
6k 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 ...
1k views

### Calculate the distance of an object in a picture? [duplicate]

I'd like to know the distance between the camera and the object, just by looking at the object height (pixels) or it's width and the real life dimensions. Here is a formula we can get on the internet: ...
135 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 ...
461 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 ...
397 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 - ...
4k views

### What is the image size of the Sun / Moon in the frame with a given focal length?

I'm interested in taking a picture of the Sun / Moon using a telephoto lens. For example like this. It would be very helpful for me to know what the approximate image size of the sun / moon would ...
158 views

### Estimating Distance From An Image [duplicate]

Assuming that the person stands parallel to a wall. The person and the wall are at the same ground level. The person takes a picture of the wall (Considering that the person always captures the bottom ...
210 views

### Why aren't dct quantization tables symmetrical [closed]

Many image compression standards use the DCT transform to convert spacial data into frequency data. The DCT coefficents are then quantized based on the estimated importance of a certain frequency to ...
15k views

### Do I use the crop factor in calculating aperture size and area?

How do I calculate the aperture size and area, considering an 35mm equivalent focal length value and non-equivalent aperture f-number (in terms of exposure, no multiplication of the crop factor of the ...
198 views

### How do extension tubes affect the image circle? [duplicate]

If you abuse your lens by just stacking a bunch of extension rings one on top of the other, will this start to affect your image circle? For instance, you have a lens that can just about cover your ...
116 views

### a general account on parameters of a camera; which are innate, which are derived, which can be processed later, etc [duplicate]

So we all know there are 3 golden parameters in camera: aperture, iso, shutter speed. I could sense those 3 parameters are innate, which means they are directly related to the mechanics of the camera, ...
1k 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 ...
256 views

### How does blur radius change with distance from the point of focus at macro distances?

In a macro situation, is there a known function that maps the blur radius as a function of the physical distance from the plane of focus? I'd expect this function to give near zero (in pixels) at ...
250 views

### What does the value of 'exit pupil' represent on a lens datasheet?

On this datasheet of the Kowa LM25HC lens I have access to, there is a number called exit pupil, which equals -57.9 mm. What does this number represent? This is not a question about what the exit ...
2k 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?
3k views

### Is there a formula for calculating exposure when enlarging prints?

I'm curious if there is a formula to determine my exposure in the dark room. Suppose my print comes out perfectly with the following: 8 seconds f/11 height of 8 +3 contrast filter Is there a ...
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): ...
176 views

### Pixels per inch relation

I have a Nikon DSLR D5500 and a 18-55mm lens and a 50 mm lens. I was calibrating the camera to get the pixels per inch using each of the lenses and all other factors like the distance from the object ...
11k 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 ...
151k views

### How do I calculate the distance of an object in a photo?

If I took a picture of a windmill on the horizon — given that I know the sensor size and the focal length of the lens and other factors to do with the shot — could I calculate how far away an object ...
979 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), ...
1k views

### Why do depth of field calculators show *more* DOF for larger formats with the same lens parameters?

I thought I had a pretty good seat of the pants understand of DOF. But I've been playing with DOF calculators and it's giving me results that don't line up with my practical experience, so I'm ...
32k views

### What is the relationship between size of object with distance?

How does the size/length of an object vary with distance? Is it a logarithmic relationship? exponential? linear? I plotted a curve of the size/length of an object for different distances from the ...
6k views

### Calculate angle/field of view from 2D image

I want to calculate the angle of view (or field of view) from a photograph, without knowing anything about the camera (or lens). Please have a look at this example: It is assumed the angle between ...
3k views

### How do I calculate the “effective focal length” of a cropped photo?

Suppose I’ve taken a photo and then cropped it. If the crop is extreme enough then I might want to go back and take the same photo with a more telephoto lens so that I can take full advantage of my ...
3k views

### Is it exactly true that doubling the focal length makes everything look twice as big?

I had come to the conclusion that if one lens has twice the focal length of another, that means it makes everything look twice as big. Conversely, if a lens has half the focal length, you see twice as ...
826 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 ...
1k views

### How do I calculate film ISO compensation for non–through-the-lens metering when using an ND filter?

I have a Yashica Electro 35 film rangefinder camera. I usually load some higher sensitivity film so I can easily take pictures indoors, but now in summer I ran into trouble shooting outside on several ...
1k views

### How do I calculate the depth of field of cameras on mobile phones with auto focus?

I just hope to learn the relationship between depth of field (DOF) with the distance on my mobile phone. When I capture one cup with the distance about 20cm from my phone, what 's the DOF? When I ...
1k 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 ...
780 views

### How can I calculate sensor size (width and height) from focus length, vertical, and horizontal angle of view?

How to calculate sensor size (width/height) when knowing focus length, vertical & horizontal angle view (FOV)?