# Tag Info

## Hot answers tagged crop-factor

15

When I started photography, this one took me ages to figure out, because people tend to explain it with a lot of math, or in a way that makes sense once you already grasp the principle but not before. How does crop factor affect perspective? It doesn't. Not at all, in the slightest. The only way you change perspective is to move the camera. Changing ...

14

When Canon released the first 1D, APS-H was simply the largest sensor they could get away with, economically. They followed it up with the 1Ds which was full frame. However the 1Ds was slower than the 1D, and offered less reach with telephoto lenses, so was less popular with sports and wildlife photographers. For this reason Canon chose to continue offering ...

14

Whether a lens is an EF or an EF-S lens, the actual focal length is always used. There are certain technical reasons why this is so, but the simplest is that a lens' focal length is defined as the distance from the film plane needed when the lens is focused at infinity to cast point light sources as a single point on the film plane. This doesn't change with ...

13

The aperture size is a property of the lens only and does not depend on the crop factor. It does depend, however, on the actual focal length of the lens (not the "equivalent" focal length). So you need to obtain the actual focal length by dividing by the crop factor. actual-focal-length = equiv-focal-length / crop-factor You can then calculate the size (...

13

Crop factor has nothing to do with T-stop. T-stop is strictly about light transmission which affects exposure. If a lens could be 100% transmissive the T-stop and f-number of the lens would be the same number, but they would still be measures of different things. T-stop measures how much light is passed through the lens, f-stop measures the size of the ...

12

For digital cameras, it's purely due to historical reasons - 35mm was the dominant size for film cameras and cinematography. As for why film cameras ended up with 35mm, I'd suggest 35 mm film and 135 film on Wikipedia as a good place to start. It's also worth noting that "35mm" is not actually the size of the image, which is 36x24 mm, but the width of the ...

11

How do I calculate the aperture size and area You divide the focal length by the aperture/F-stop value. Infact, that's what the F-stop/aperture value is. It's a divider. Sometimes written as ƒ2.8 (as an example) but a lot of people leave out the vinculum and should be written as ƒ/2.8. Replace the ƒ with the focal length and that's the diameter of the ...

10

Perspective is determined by one thing and one thing only: Subject distance. Period. If you took an image using a rectilinear wide angle lens such as 17mm, which yields a diagonal angle of view of 104° on a full frame/35mm camera and cropped the resulting image so that only the center 3.08333° is in view, you would have the exact same perspective as if you ...

10

Nikon 1.5X APS-C sensors in their current lineup are actually 1.52-1.53X depending on the exact measurements of the various different sensors in different models. Some older, discontinued models in the D3x00 series are slightly smaller at 1.55-1.56X. The difference between 1.52X and 1.53X is 0.65789 percent. The difference between 1.5X and 1.53X is a mere ...

10

Assuming that the quoted 1365mm focal length is in 35mm full frame equivalent terms (because otherwise, it would be huge), then the actual focal length of the lens assembly is around 1365 / 5.6 ~= 244mm. To accomplish an equivalent 1365mm focal length with a 1.6 crop factor, you would need about an 854mm actual focal length lens. I'm not aware of anything ...

9

The minimum focus distance is a property of the lens and the distance to the sensor. The lens-to-sensor distance is the same for all Canon DSLRs hence the minimum focus distance doesn't change when using a cropped sensor body. There are adapters you can get to magnify the viewfinder image, here's a review of an offical Canon product, numerous third party ...

9

I think you should, in fact, use the slightly-smaller value. That's not because I've measured, but because I can resolve the apparent contradiction from exiftool: it's showing you a rounded value. Try giving it the -n flag, to disable what exiftool calls "print conversion": \$ exiftool -n -ScaleFactor35efl sample.jpg Scale Factor To 35 mm Equivalent: 0....

8

Here's the short answer: a wide angle lens on a crop sensor skews the image exactly in the way it does in the center of the frame on a full-frame sensor. In turn, this means that using a wide angle lens (small focal length) on a crop sensor gives the same perspective distortion as using a narrower lens (larger focal length) on a full frame sensor, with the ...

8

Well, the main thing is that crop factor doesn't really affect focal length. It just affects the field of view by making it narrower. So, what you really have is a 400x1.4x => 560mm lens combination on a crop body, which has the same FoV that an 896mm lens would have on a full frame body. So, unless you shoot full frame enough to translate focal lengths to ...

7

Because the standard size for film cameras for a long time was 135 film which measures 35mm in width including the perforations and leaves enough space for a 36x24mm negative size. Since the Field of View (FoV) for any particular focal length lens is determined by the size of the film or sensor onto which the image circle is being projected, over time ...

7

The crop factor applies to all lenses shot on camera with a smaller sensor. They look the same because 70mm is 70mm on both lenses, and they're both cropped in exactly the same way. I think the answers to Is an EF 50mm f/1.4 the same as 50mm with an EF-S lens on a Canon 550D? should help. Also check out my answer to What is Angle of View?, because the ...

7

Crop factor is expressed as a ratio of the linear measurements of a sensor compared to a 36x24mm 35mm film frame or a full frame sensor. This is because a sensor exactly half as large as another will also provide exactly half the angle of view as the other with a lens of the same focal length. Or conversely, a sensor half as large requires a lens of half the ...

7

The "equivalent" focal length draws from history, namely how it relates to a 35mm film camera, and there should come a time (and I think it is past) when we move on. The focal length IS the focal length. Having a smaller sensor may crop a portion of the field of view, but the focal length is a real and meaningful number. Anyone who is interested in the ...

7

In photography, what is interesting is mostly the angle of view (AOV). The AOV is the angle that a lens offers on a sensor - it can be specified horizontally, diagonally, or vertically. AOV [°] = 2 * arctan ( sensor_height|width|diagonale [mm] / (2 * focal_length [mm]) ) The formula to get from a specified focal length (FL) on a non-full-frame sensor to the ...

7

Neither the focal length of the lens nor the aperture of the lens change if we change the size of the sensor. What does change is the angle of view and the depth of field, but not the exposure. (We are assuming neither the focal length, f-number, the camera position, nor the focus distance to our subject changes - only the size of our camera's sensor.) We ...

6

Everything in product design is a comprise and Canon wanted to provide a solution to combine high-quality and high-speed for sports photographer. It did so with the 1D series. Its APS-H sensor and relatively large pixels make it sensitive to light and possible to shoot at high-speeds, up to 10 FPS with the 1D Mark IV. At the same time, the full-frame 1Ds ...

6

There are many various film and digital sensor sizes and formats. 135 film (also known as "full-frame") became the most used film in the 60s and the most common format was 3/2, meaning 36mm x 24mm frame size. The camera determined the format/ratio but was always 24mm high. There were even half frame cameras that used this film but would result in ...

6

No. You can imagine the micro4/3 to simply cut out the middle of the image. If you had a 25mm lens on a full frame camera and exposed it properly, the middle part of the frame is part of what's exposed properly. The definition of f-stop factors out the lens length so only f-stop and shutter speed determine the EV (exposure value). Let me make this clear: ...

6

The f-stop is a simple ratio. It is the focal length divided by the working diameter. We use this value to compare the image brightness of one lens vs. another. The f-stop is often in error because it does not take into account light loss due to reflections from the polished surfaces and the lack of perfect transparency of the glass. The "T" -top is ...

6

Not correct. Perspective (referring to the size and spacing of background objects relative to subject) is determined by only the distance of camera to subject. This is the geometry drawn from the camera position, regardless of any camera details. Another focal length or another camera crop size (and subsequent enlargement to equivalent size) can "magnify ...

6

It doesn't really matter, but two decimal digits is more precision than is practically useful. ... or is it standard practice to round to only the first place with crop factor? This is good practice, if not always standard practice. That's because in practice, it doesn't matter. Few other things are going to be so precise that going to two decimal ...

6

Well, sort of. There's no such thing as absolute equivalence. In terms of angle of view a 55mm lens will give the same AoV with a 1.5X APS-C sensor as an 85mm lens on a 36x24mm FF camera. In terms of exposure you'd need a 55mm f/1.8 to get the same AoV and exposure in the same light as an 85mm f/1.8 on a FF. In terms of depth of field (DoF), you'd need a ...

6

Theoretically, optically, it would work (for low-quality values of "work"). Yes, the focal reducer would give an extra stop of light. But because the 2x teleconverter is responsible for 2 stops of light loss, you'd still net 1 stop of light loss. Aside from the optics math, there are some real practical problems with this approach. Depending on exactly ...

6

A full frame sensor gathers more light for the total area, but that's because there is more total area. The light gathered for the same sized portion of the recording medium is the same for any combination of f-stop and shutter speed — no matter the total size. This means that if you are getting the exposure you want with f/8 and ¹⁄₅₀₀₀th at ISO 640 on one ...

Only top voted, non community-wiki answers of a minimum length are eligible