Questions tagged [calculations]

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

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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 ...
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 ...
7k 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 ...
28k views

How to calculate the FOV in degrees from focal length or distance?

How does one to calculate the field of view (or angle of view) in degrees from the following details: sensor size (for example, 1") distance to target (for example, 7 feet) focal length (for example,...
30k 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

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 ...
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 ...
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 ...
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 ...
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

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 ...
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 ...
844 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 ...
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 ...
294 views

Where can I find photos taken by a calibrated camera to make a 360° panorama? [closed]

I am trying to write up an automatic 360° panorama stitching program for my final project, in order to do so, I need to accomplish four steps: Find the horizontal and vertical field of view for a ...
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 ...
18k 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).
466 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 ...
35k views

Is there a formula to calculate DOF?

I am pretty clear about that DOF depends on: Focal length Aperture Distance from subject Sensor size and more (as pointed in the comment). But what is the question here is: Is there any formula that ...
773 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 ...
13k 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 = (...
4k views

Can we measure size of an object using EXIF data from a photo?

A lot of people have asked if we can measure the distance of an object in photo. But I was wondering if we can measure the size of an object in photo. Of course assuming we know everything from sensor ...
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 ...
999 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 ...
778 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 ...
216 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 ...
17k views

How can I calculate focal length from a photograph?

I posted this question over on Stack Overflow, but someone suggested this site might be of more help to me. I'm doing a college project where I'm trying to calculate the focal length of a camera ...
483 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 ...
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 ...
144k 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 ...
210 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 ...
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,...