How to calculate crop factor Videos

Yep that's right, but if you choose to use the 30mm, you will have different levels of compression in the images. Long focal lengths tend to compress the image, so the background will look bigger and closer to the subject like with the wide focal length. Wide focal lengths distort the image, so the nose of a person will look bigger than the rest of his/her head. That is why long focal lengths are used for portraits, they "flatten" the face. It will look more flattering to the person.

so if I buy a lens designed for a full frame camera like the AF-S FX Nikkor 50mm/F1.4 G and use my D7000 I would get a 75mm/F2 lens....and if I would buy the lens designed for ASP-C camera I will still get the 75mm lens with the only difference i will get very strong vingeting on the FF and because of that I cant use it ? or how does it work ?:)

I love these videos, but can I make a suggestion? Female photographers! I see women being used as photo subjects, but everyone else (the host, the photographers, the assistants, the "scientist") are all men.

As always, your videos are articulate and well presented. Thank you. I was hoping thought you would have addressed the reason that there is a crop factor. What is the physical reason that causes a crop factor?

Hi, I have a question about equivalent focal length that I have been trying to find the answer to for several hours. I have a Nikon D3300 APC-S camera, and my mom has a Nikon D600 full-frame camera. I am thinking about getting a Nikon 50mm 1.4 FX lens to use with my D3300. I can't figure out what that would look like though. The D3300 comes with a 18-55mm kit lens. I am confused as to whether the 50mm would be equivalent to setting my kit lens to 33.3 mm or to 75 mm (outside its range). Thanks.

i think that ur video is not 100% correct , pixel density cant efect focal length plus the total light gathered is also effected and aputure needs to be multiplied by the crop factor aswel

I am not so sure your video is correct. The overall sensor size (physical dimensions) determines the crop factor. The number of pixels of the sensor and hence pixel density is irrelevant! In other words - if a Canon FF sensor is the same physical dimensions as a Nikon FF sensor then they both have the same field of view with the same lens. The higher MP of the Nikon have no effect on the angle of view of the image projected. We are talking about an image being protected onto a rectangle. The smaller the rectangle the narrower angle of light reaching the rectangle and greater cropping of the projected image. Think of a slide projector shining on a wall. You then draw some rectangles on the wall where the image lands. The smaller the rectangle the greater the cropping of the projected image. Where does pixel density come into it? Simple answer: it doesn't. Having read more of your information I see you may be right. It is hard to tell without doing some real world tests or calculations. I really like the way you think and you may well have this nailed.

No it isn't. This is wrong. Jared did not explain this correctly. With the same lens, you get the same perspective in both cameras. The only difference is that on an APS-C (cropped) sensor, you will only see the CENTER of the entire image that you would get on a full frame camera. If you have a full frame cam, you can always recreate what you would see on a cropped sensor cam by cropping the image and leaving only the center. Basically, full frame is always better (but more expensive).

Have you sent this in to him? It's a very good question indeed.

I think you bring up a good question here that needs to be answered as it is a common one in photography, and in a wider sense, an intially challenging concept to understand in radiometry. I've studied optics in grad school and feel like i understand the underpinnings of the question at hand. Aperture is defined as the measure the focal length of a lens divided by its entrance pupil. That is something that is inherent in the lens itself. It is a direct reference to the ability of a lens to gather light. For a given entrance pupil (i.e. - lens diameter), a shorter focal distance corresponds to more light gathered. Because of this, when you use a crop sensor body, there is light gathered by the lens that is lost on the sensor, thus making it the equivalent of a longer focal length with a narrower field of view. With the decreased field of view also comes a decreased f-number since its ability to gather light has been diminished (essentially your sensor becomes the entrance pupil instead of the aperture stop in the lens). What this means for a Sony/Nikon crop factor of 1.5 is that a 50mm lens f/1.8 (35mm equivalent) will give the same background blur, depth of field, and field of view as a 75mm f/2.7 (1.8+.5*1.8). This is what geometric optics has to say on the matter and it's what Tony was trying to explain. In the case of this test what you are looking at is the digital readout of your sensor. When you do a digital crop on the image, it isn't changing the image that was formed in total; it's the equivalent of putting some construction paper around the outer half of a portrait on the wall in order to crop it. It doesn't change any of the physical properties of the image. However, if you were to increase the physical crop factor of your camera, a different field of view would be obtained (focal length) and you would end up with a new depth of field to your image. Bottom line is that a digital crop does not change the angle of view of an image formed on your sensor so it will not effect the depth of field of the image formed thereon.