Aperture: Equivalent Focal Length
so equivalent aperture has something that is a terminology that came around. I did not learn about this in college. This is only come around. Really. In the last five years or so, we talked about equivalent angle of view At the beginning of this class, we have a full frame camera that has a 50 millimeter lens which sees degrees on it. And in order to get that same angle of you were using the 35 millimeter lens over here, does that mean that they are identical? No, it doesn't. It means they're equivalent, which means they're very close. There's some aspects that are saying, but there are some aspects that are different when we compare a 50 and a 35. Are those the same lens? No. Do they have the same depth of field? No. They are different in those aspects will carry forward, no matter what sensor you are using them on. As an example, if we're shooting with a 50 millimeter lands on a full frame sensor, have 1.4. We're gonna get this shallow depth of field. We put a 35 on our crop frame s...
ensor. We're gonna get shallow depth of field. But the depth of field is not exactly the same because 50 millimeters exhibits a shallower depth of field because it's a longer focal length van does the 35 millimeter lens, and so they may see the same angle of view. They may be able to sit in let in the same amount of light with one point for aperture. But they are not equivalent when it comes to depth of field. And so if we were to stop the 50 millimeter down to F two, we get just a little bit more depth of field. The background is a little less blurry, and these are equivalent apertures. And so if you have a crop frame camera and you have a lens that goes down to 1.4, well, that's angle of view. That's kind of a separate issue as far as 1.4. They let in the same amount of light, yes, but the depth of field it's a little bit greater with the smaller crop frame and a little bit less with large frame. And so where this really comes into play is people who want super shallow depth of field. I want to focus on the face and have the background go way out of focus. Those folks tend to prefer working with full frame cameras because they enable us to use lenses that get even shallower depth field. And so there have been endless arguments in the forums in the chat rooms, about comparing lenses. Well, I have a crop frame camera and I have a portrait lens that is the same equivalent. It's the same angle of you. It's the same aperture, and then somebody else who owns full frame would come in and they say You don't have the same lands It's a different depth of field and they would say But I have the same angle of view and I have the same light gathering ability. But you don't have the same depth of field and they go back and forth fighting, fighting, fighting. And there's three factors, two of which are exactly the same. The angle of you is the same. The light gathering is the same one after, or that one feature is different, and that is the depth of field, and it's one off. It's not a huge deal, but just don't get caught up in the arguments in the forums. They're all sorts of thugs in there that will beat you up for saying something. Okay, so ah, 300 millimeter lands is going to see seven degrees from side to side. If you want that same angle of view on a crop friend camera, you only need a 200 millimeter. Let's so these have an equivalent angle of view. Same angle of you. They let in the same amount of light. It's both 56 but they going to exhibit a slightly different depth of field. So here's our example of our subject in focus in the background that is a little out of focus you'll see with the full frame camera. Ah, 300 millimeter lens exhibits shallower depth of field. So our trees in the background are a little bit more blurry, and at every aperture you go if you stop them both down to stop to F aid. The full frame sensor has shallow word up the field at every equivalent aperture that you said it every identical aperture that you said it at, and if you want it to get to look fairly similar, you would actually have to stop it down to F eight or so. And so roughly there is a one stop difference in the depth of field that you were getting. So if you have a crop frame camera, you're always getting about one. Stop mawr depth of field with every lens that you're shooting at when you're comparing equivalent focal wings. And so it's one of these very subtle things that a lot of people like toe beat you up on if you say it in slightly the wrong way and the wrong place, and so 50 millimeter versus a 35 same angle of you because we have different sensors. We talked about this earlier, so the same aperture, same low light ability. They're both 1.4 is both. These photographers can work in the same low light environments. They're gonna get the same angle of view, but because they're using different lenses, they're gonna have different depth of field. Same focal length. You get the same depth of field, but these are not the same focal length. So you're gonna get different depths of field. You're gonna get slightly moored up the field with the slightly less step the field with the 50 in this particular example. And so that's the equivalent aperture in the equivalent focal length that you've probably heard if you've been reading some articles about the crop frame sensor, and it's because we're using different size sensors and we've always had this issue. But it was more with 35 millimeter and medium format and large format and less people had, we're going from 35 to medium format. So it's become Maura part of the dialogue these days because, well, we have kind of a big dividing line. And we have a lot of people on both sides of the line as to why we're talking about all this different terminology, and it's a little bit hard to keep straight. And if you're still a little confused, I can understand that it is a little confusing. Go back through the material again and again, and it can, and it will eventually make sense. I certainly hope and so little break point before we go on, just to see if there's anything we need to address. Well, I think first of all, this is where my brain starts to be, like, uh, What about you guys? And like, Oh, okay, that is definitely one that I haven't had explained to me in that way before. So thank you. Um and so just Teoh push that one home. Hamburgers had asked her age. Amber's with some votes. So can you confirm that on crop sensors that the F stop of a lens is also multiplied by the crop factor so similar to what we're talking about? The example given is 55 millimeter lens at 1.8 on a 1.6 crop factor. Is that really the same as an 80 millimeter lens on F as an F 2.8 would be on a full frame? Yes, they are correct in that. And so that's exactly what you were just complaining. I wouldn't want to be careful because we're getting It's a very precise wording on Yeah, it's the equivalent look in depth of field. But it's not the same light gathering ability because they still have their good light gathering ability. I think in their example of a 1.8, because they say it's the equivalent aperture of 2.8 in the look of how much depth how much depth of field, but as far US light gathering ability, it's still the 1.8. And so if a lens says 1.8, that's what it's gathering until you hear otherwise.