13
votes
Accepted
Why doesn't the focus distance at which my lens has magnification 1 match the formula?
The equation assumes a simple single element lens that is bilaterally symmetrical. The camera lens, to mitigate the 7 major aberrations (shortcomings that degrade) is constructed using several ...
- 39.5k
13
votes
Why is distance absent from the exposure triangle?
You do get less light as you move further from a object. However, that less light is focused on a smaller area. It so happens that the two effects cancel out, and the focused image of a object will ...
- 17.4k
9
votes
Why do you need to change your position rather than just focal length to affect perspective?
Perspective is the size relationship of objects. You might say the ratio of size of foreground objects to background objects. Perspective plays a big part when it comes to judging distances to objects....
- 39.5k
9
votes
Why doesn't the focus distance at which my lens has magnification 1 match the formula?
first of all, kudos on your effort to break a photography problem down to first principles.
The discrepancy you've observed stems from a common oversimplification. Your 100mm Lens is actually what ...
- 1,999
8
votes
Backyard wildlife zoom question factoring distance
Given the ratio of the Canon APS-C crop factor (1.6) to the MFT (2.0) sensors, the equivalent of a 300mm on your camera is 300*1.6/2=240mm so a bit longer than your intended lens (200mm).
The zoom ...
- 21.7k
8
votes
Accepted
Backyard wildlife zoom question factoring distance
Assuming all other things are equal:
Your Canon 80D has a crop factor of 1.6. This means that your 300mm lens has an effective focal length of 300mm × 1.6 = 480mm.
A micro-4/3s camera has a crop ...
- 22.1k
6
votes
What is 'sensor height?'
Sensor height is indeed the physical measurement of the vertical dimension of the sensor's active pixel area.
From Wikipedia's Image sensor format article, the phone's sensor format of 1/3" (actually ...
- 33.2k
5
votes
Accepted
Does aperture really matter if the subject distance is large?
That observation is true.
The nearer to the lens, the smaller the depth of field.
If you use an online DoF calculator like e.g. https://www.dofmaster.com/dofjs.html you can easily see this.
...
- 4,983
5
votes
Subjects not focused when they are too far away
I'm not really seeing that any distance is softer than another.
Using screenshots at 100% zoom, I've focussed in on one significant area of each.
From this distance, they each look as soft as the ...
- 23.4k
4
votes
Why is distance absent from the exposure triangle?
The inverse square law applies to the distance between the light source and the subject. It doesn't apply to the distance between the subject reflecting the light and the camera in the same way.
This ...
- 176k
4
votes
Why is distance absent from the exposure triangle?
The exposure is based on the amount of light hitting the subject intertwined with how much light is reflected from the subject. Thus the exposure remains a constant regardless of camera to subject ...
- 39.5k
4
votes
What is 'sensor height?'
I find that the diagonal measure of this sensor image is 5.867mm. From specification I can't find, the height and length. However, based on the height to length ratio 1920 pixel length by 1080 high I ...
- 39.5k
4
votes
Accepted
How to find an angle and a distance for clicking picture of a distorted artwork to achieve 3D effect?
As this is the photography forum I will try to make a good approach using one. You need a camera with some kind of live view preferable.
Get a tripod and position your camera pointing to the sheet of ...
- 25.2k
4
votes
Backyard wildlife zoom question factoring distance
The formula for determining the focal length required to fill the frame with a subject is pretty simple:
FL= sensor(distance/size)
So for your example, to fill the width of an m4/3 sensor (18mm), ...
- 18.8k
4
votes
Accepted
Is x50 zoom camera able to zoom 500 meter target area from a 6 km distance?
By calculation angle (which is to the camera) of this triangle is around 4.7 degree.
So on one of the length of zoom you will be able to fill the frame with this object.
But the quality on such ...
- 12.4k
3
votes
Simulating increasing image distance
Short answer: you can't do it with just one image.
Long[er] answer: to realistically simulate distance change, you need either multiple images taken from multiple different subject distances or to ...
- 2,055
3
votes
Physical Distances at the edge of a photo compared to the center
Yes, if you ignore barrel/pincushion distortion.
Distortion aside, a camera projection obeys the pin hole camera model. Under this model straight lines in the scene are always rendered as straight ...
- 119k
3
votes
Why do you need to change your position rather than just focal length to affect perspective?
To quote Ansel Adams The Camera:
"...moving closer to the subject causes nearby objects to grow in apparent size more rapidly than distant ones, so their relative sizes change. In contrast, changing ...
- 223
3
votes
DOF change when keeping subject size same in the frame
Longer focal length lenses have shallower depth of field (DoF) than shorter focal length lenses if both are set to the same f-number when both are used at the same subject distance.
On the other ...
- 176k
3
votes
Calculation for getting dimension of object in image not working
You are missing something big. The size of the camera sensor is not mentioned. You need to know it, both in mm and in pixels. You didn't say any sizes, but Samsung says 3.7 megapixels, so if 4:3, ...
- 12.9k
3
votes
Distance from camera to have the photo print out as it's actual size
I am trying to fix my vinyl floor...
Sounds like it would not ruin the aesthetics of your photos if you laid a ruler on the floor, and included it in the frame when you took the picture.
My own next ...
- 635
3
votes
Calculating the size of an object from a single image, given the distance from the camera
You can calculate that distance given the formula for the pinhole camera model (which is an approximation, but should work well in the cases of interest). You need to know the focal distance (which by ...
- 219
2
votes
Accepted
What is ideal distance to subject for head and shoulder portraits?
This is a good question but many of the existing answers seem really convoluted and off the point.
All that matters is distance to the subject, as this is what defines the distortions of facial ...
- 136
2
votes
How to determine film size from smartphone image exif data?
From the Exif data: Image size is 2988 pixels height by 5412 pixel length. The file states the actual focal length is 4.8mm. The file states this value is the equivalent of a 31mm lens mounted on a ...
- 39.5k
2
votes
Calculation for getting dimension of object in image not working
@omega Here's what you are not getting: The 36x24 measurement is the size a classic photo negative taken with 35mm film.
It is a well known and accepted measurement. 35mm film was a very commonly ...
- 176k
2
votes
DOF change when keeping subject size same in the frame
For the EDIT: that's since 50mm and 85mm lenses are optically different. The DOF is part of the characteristics of the lens.
A longer lens compresses the image more, notice the difference in the ...
2
votes
DOF change when keeping subject size same in the frame
The span of DOF depends on the tolerable diameter of the image disks that comprise the picture. All lenses image by projecting an image made up of a googolplex of tiny image discs. It is the size of ...
- 39.5k
2
votes
Accepted
Calculate the distance of an object in a photo Android
This is actually a simple ratio problem you can solve easily with a basic calculator
.
We can a trace light ray coming from the top of the object to the lens. We can a trace light ray coming from the ...
- 39.5k
2
votes
Why do you need to change your position rather than just focal length to affect perspective?
Perspective is all about the angles at which light rays reach the lens. If the light rays coming from the sides of one object are closer together (a smaller angle) than those coming from the sides of ...
- 490
2
votes
In photography and videography, what is a long shot / wide shot?
[I need to come back to this with more time tomorrow & bring my almost famous bear & bookcase]
Long & wide are not polar opposites.
Either can be based on lens focal length and/or ...
- 23.4k
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