The Crop Factor Myth Explained 

There's one major mistake, the compression is not due to the focal lenght but is due to the relative distance of the subject and the background from the sensor. So if you take a S35 camera with a 50mm lens and shoot a scene, and then, without moving anything, you shoot the same scene with a 16mm camera with a 25mm lens (same field of view) you will have the exact same compression of the background.

Bit of a swing and a miss on this one. I had to stop when you stated that the lens creates compression. Aside from the unique characteristics of each lens (sharpness, aberrations, etc), you will indeed get the exact same image if you use the crop factor principle. What's commonly forgotten though is that the crop factor applies not just to the focal length, but to the f-stop too. Framing up a head-shot on a Super 35 sensor with a 100mm lens at f/4 will give you the exact same frame, compression, DOF and distortion as staying in the same position and switching to a Super 16 sensor, with a 50mm lens at f/2. The only difference will be the exposure change due to the new f-stop, but this is also equaled out by the difference in sensitivity between the two sensors. All else being equal, a Super 35 sensor will show a similar amount of noise at, for example, ISO 3200, as a Super 16 will show at ISO 800, due to the smaller sensor having a worse signal to noise ratio given the smaller area on which it is registering light. I'm a fan of your channel, so don't take this as an attack, just a correction.

The lens does not "compress" the image. So-called compression is an effect of perspective. As you move away from something, it becomes relatively closer to the background. Making them seem closer. A 25mm with a 2x crop will have the same "compression" as a 50mm with no crop. It's the same perspective change that makes stars feel like they're inches apart, despite being lightyears apart.

Compression does not work like this. That's just a matter of distance between the camera and subject. You wouldn't use a 50mm as a "wide angle" close up on a s35mm being right in front of the subject, instead you might use a 35mm to get a wide close up. But if you put a 35mm on a 65mm you need to be much closer to the subject to get the same framing and therefore you get a more distorted wide effect. If you take a 50mm on a large format camera, match up the aperture a few stops for the same bokeh as a 35mm on a s35 sensor, frame it the same, they will look identical. The only two things that differs is that the resolution and glass distortions become much more visible the further out of the image circle you get; which leads to more lens artifacts visible on larger sensors, alternatively if the image goes into the extreme wide, the s35mm requires much wider lenses for the same effect and extreme wide angles usually are harder to get without heavy glass artifacts. The second part is covered in the video, but it's not as simple as this. You can match up much of the look between s35mm and large format, to a point. It's when you get into wider images that larger sensors show their prime. If you use a 24mm T1.4 for a really wide shot on s35mm with a shallow DOF, you get the same on a larger sensor with increased focal length around T2.8, but if you try to go wider on the s35mm you cannot retain the shallow DOF as wider lenses cannot be that fast. The larger sensor however can still go lower and retain a fast T-stop, resulting in a shallow DOF at lower focal lengths. So, you can get the same image on a s35mm sensor using a 35mm at T1.4 as a large format sensor with a 50mm lens stopped down. But as soon as you open that 50mm up you reach a DOF that isn't possible on the s35 sensor. The only way for that sensor to get a similar image is to go below T1.0 and that's a hell hole for glass clarity. This is the sole reason why larger sensors produce a shallower DOF, but the lenses do not compress or change any other aspects other than imperfections at the edge of the image circle.

I'm usually a big fan of your videos but i think you should delete and re-do this one. You got a few things wrong in the background compression section. The only real difference in image between sensor sizes is the amount of background blur, but this has nothing to do with the sensor; it's just that a 30mm lens at f1.4 generally has less background blur than a 50mm at 1.4 if used from the same distance, and you need a larger focal length with a bigger sensor to achieve the same FOV as with a smaller sensor. In theory, if you had a sensor with infinite resolution, you could shoot everything with say a 16mm lens and then crop in later to get every other focal length. The only thing that dictates background compression is the position of the camera.

yikes... you got the section on "compression" completely wrong. it is NOT a function of the focal length. it is a function of DISTANCE FROM CAMERA. in all the cinema books where they're showing you the differences in focal length on image compression, they're actually MOVING THE CAMERA in order to keep the subject the same size in the frame. THAT is what causes the difference in compression. so for example, if you take the typical example of shooting telephone poles receding into the horizon vanishing point - if you shoot that with a wide angle lens, the poles CLOSER to camera will look farther apart. but in that exact same shot, shot with the wide angle lens, if you zoom in on the telephone poles in the distance with a magnifying glass, their distance from each other looks COMPRESSED. those poles, at that distance, shot with a telephoto lens to fill a screen will have the exact same compression that was visible when shot with the wide angle lens... it would just fill the screen.

I want to clarify things up. Its a hard thing to say, but the compresion effect you were referring to as the result of the focal lenght of the lens used does, in fact, hypothetically, depends solely and only by the distance between the camera and the subject not precisely the focal lenght itself. the focal leght of the lense does only one job -- cropping the image in front of your eye into preferred sizes, in other words, control the field of view. let's say we are to shoot a shot opted for medium shot size, on a full frame camera (namely large format for cinimatography). you would be needing 50 mm focusing at 1.0m to get that shot size on this sensor size -- this shall be our control set. Then, we are to shoot this same shot on a camera w different sensor size, -- lets say super 35 having a crop factor of 1.5 compared to Full frame(LF) -- if we use this same 50mm lens focusing at the same 1.0 meter the image will come out to be 1.5 time croped, maybe it will become medium close up, so you will either need to move the camera backwards to, lets say, 2 meters to get the same opted medium shot, which creates a compression effect on the background and ,hence, has more feeling of dimensionality blabla , or -- more normal usual way -- change the lens in front of this super 35 camera into a 35mm which will give 50mm "FULL FRAME FEILD OF VIEW EQUIVALENT" and be able to shot at the same 1.0 meter focusing distance. Apart from this, talking about depth of feild (aka background seperation aka bokeh) is a different subject and is already mentioned correctly in the video. I am currently teaching cinematography in an art school using mainly the pocket 4k having micro 4/3, and was a photography using a normal full frame dslr. honestly, there is no actual difference form this crop factor "compression " and "dimensionality" kinds of things (apart from the size of the bokeh which no one who actually shoot cinematograph cares about much once its already shallow enough). You just need to know how to choose what lenses to used. The only concrete enough differece ive heard so far is about the difference in lens designs for each "focal lenght" which tends to make the wider (lower number) prone to more distorsions and spherical abberation and conversly, the longer(higher number) prone to chromatic abberation, but, honestly, in this era, should be all taken for granted.

after reading all these comments, it has reaffirmed my understanding that most people are still “spec & technical” guided rather than “creativity & feel” guided, which for me is more important in the field of cinematography.

All someone needs to do is shoot with 2 different focal lengths from the same spot with matching depth of field (ie. 25mm @ f/2 vs 50mm @ f/4), and then crop to match. The compression, bokeh, and distortion should look pretty much identical if the optics are of similar quality, but the image fidelity is higher on the larger sensor. Optical distortion varies from one lens to another - if someone compared a highly-corrected wide-angle lens to a pancake lens of a slightly tighter focal length with a ton of barrel distortion and then cropped to match, then you might think the tighter lens has more of the wide-angle distortion look.

As others have explained compression has nothing to do sensor size, I’d also like to point out that depth of field differences can also be compensated e using different aperture stops. For instance shooting Master Primes on Alexa 35 at T1.3 versus shooting Signature Primes on Mini LF at T1.8, when matched for framing should yield largely identical results (lens characteristics aside). The super 35 setup also has the benefit of one extra stop of light when needed

Just to be clear: isn‘t the 1x crop factor referring to 35 mm wind up film in photographic stills cameras? Which is apparently larger compared to the S35 sensor area. I think that debating about crop factors and sensor sizes in digital cinema technology first started when people used full frame lenses on their (digital) APS-C or mFT camera bodies - which in the first place were DSLRs. The so called „full frame image circle“ was - as far as I know - never a significant measurement size for cinema lenses. Although lenses for larger format film areas like 65 mm negative stock existed since the mid 1900s. There are of course 0.x crop factors which refer to sensor/film areas larger than „digital“ full frame or 35 mm celluloid stills film but I think the 1x crop always referred to what is called „full frame“ (nowadays).

If you have ever used a zoom lens you should immediately recognize that compression doesn't exist. Zooming in changes the focal length, yet zooming in expands the image the same as 'cropping in' on the sensor, same as zooming in in post. The one exception is that at a constant f-number, the zoom lens will make the background more out of focus as it zooms in. All lenses (outside of special machine vision lenses used in manufacturing) have the same perspective. Fish eye, 10mm, 1000mm, anamorphic - they just have different magnifications. Another way to convince yourself is to think of why objects don't look darker as they get further away. We know further away light sources dim by "one over the distance squared". Well all objects imaged by a lens also are rendered smaller by "one over the distance squared" - twice as far away and they appear half as tall, and half as wide, so one quarter as big, and so the light per area in the image never changes.

There is no lens compression. Compression or perspective is achieved by only the distance and the framing. How the framing is done is not relevant. I know this may be hard to get. It was for me 45 years ago. With depth of field you are right but it can be fixed by opening the aperture more on a small sensor - if possible (unfortunately it often is not and that is why larger sensors are preferred in photography)

2:07 "28 Days Later" was shot on Canon XL1S cameras: they were 1\3'' machines. 3:13 Sorry, but the standard everything is derived from is full frame. That's the "1x" format. As such, Super35 has a crop factor of approximately 1.5x (different sensors have a slightly different diagonal while with film it really depends on the amount of perforations and wether or not you're shooting open matte).

You went through this entire video without talking about aperture and how you DO get an identical image if you also apply the crop factor to the aperture. 27 mm f/1.4 on APS-C (photography term) / Super 35 (cinematography term) will look NEAR IDENTICAL to 41 mm f/2.1 Full-frame (photography term) / Large Format (cinematography term)

please stop with the compression lie. its distance.

Thanks, I was about to buy a Pocket 4k, but because of this video I am purchasing an Alexa 65 with DNA primes. Thank You!

Ironically there is one major misconception in your video. Yes the sensor doesn't influence anything and it's the focal length that matters, but again that's not the actual millimeters on a lens that do that. It's all because of magnification ratios within the lens element, and the entrance pupil. For the depth of field for exemple, it's because to get the same aperture number, you need to physically enlarge that pupil. a 24mm f/2 as a much smaller entrance pupil diameter than a 85mm f/2, and this IS the parameter that changes depth of field. (if you close the iris to match the physical size of the entrance pupil of the 24mm, you will get the same DOP) So focal length is a consequence but not the direct culprit of those changes. In similar fashion, the actual focusing plane isn't on the sensor or film gate either, it's on the nodal point of the lens. In a lot of cases it isn't that impacting but for very long focal length at close focus, or macro shots it does matter. and that nodal point slightly moves in and out depending on the focusing distance.

What Mic do you use? On your RU-vid videos?

FYI super 35 (1.5x crop factor) and full frame 35mm (1x crop) are different things 3:21

I think focal length itselt doesn't directly affect the depth of field. It's basically the distance between the camera(sensor) and subject that decides the depth of field. And also you have to decide the correct aperture to create the desired shallow/deep depth of field.

Take a full frame lens, change the back elements to narrow the image circle to match S35 (similar to how speed boosters work), you get the same FOV and DOF, but a higher exposure output, which in-turn, would help against the slightly worse sensitivity of the S35 sensor. This is why you tend to get faster APSC lenses relative equivalent Full Frame FOV. The relationship to the numbers change but thats about it. I think the differences between sensor size lay in the technicalities of the manufacturing and marketing departments.

thank you for your content Sir, are you UK based? and Will you ever consider some live workshops?

Sorry to pile on but it's not called a "micro four thirds sensor" (2:12). "Micro four thirds" refers to the camera system that uses a 4/3 sensor but doesn't have a mirror. Thus the cameras can be smaller (micro).

Great video once again, thank you.

Bokeh and depth of field has always been a lens characteristic, never a sensor characteristic.

Great job. Thank You.

We love you homie but compression works differently than you explained

Could you do a cinematography style video for Bruno Delbonnel?

One big question. Is s35 equivalent to full frame? Or in cine world the standard sensor size is s35 (aps-c) instead of full frame?

There's one thing I don't quite get with crop factors smaller than 1. When they're bigger than 1, it's because the sensor only uses a part of what the lens let's through. So how does it work with factors smaller than 1? How can it get more data than what the lens can give?

S35 has a cropfactor of 1.4-1.6, or am I missing something?

S16mm and 16mm as a crop factor around 3. 3.41 in almost 16mm cameras. Blackmagic pocket cinema camera, 2.88 crop factor. MFT 2 crop factor ang GH5S 1,79.

I've been using MFT for almost 20 years now and finally understand what all my lenses do...

Thank you for information. From India

Great video.

Oh my god please don’t peddle the bigger sensor size = more compressed garbage, this is misinformation that makes absolutely no sense. Larger sensor allows for more bokeh, more detail, potentially smoother focus rolloff, but does NOT magically compress the image to make it feel “bigger”. All of the other things are what have that effect. Compression is an effect of distance from the subject to the camera, and field of view. Almost any field of view and distance to the subject can be achieved on any sensor size (for most shots).

Super35 is crop factor 1.0 when we are in Cine Mode?

Thank you for the video. 5:51 / 13:23 "...a wider focal length you will need to use" should probably be "A wider field of view you will need to use". You mention it yourself later in the video; that there are long and short focal lengths, but that it has nothing to do with the lens' field of view. An S16mm lens does not cover the image circle on a large format image chip, no matter if it is an 18mm or 75mm lens. There are of course some exceptions, for example the Zeiss Jena Biotar 50mm f:1.4 from the late 1950s, which covers the S35 format even though it is a 16mm format lens.

Will tie the "master photographer" who administered my journeyman-exam to a chair and make him watch this clockwork-orange-style. Dude hated my work based on it being shot on 6x7cm film (180mm lens) instead of a 35mm digital camera. Well, I think he mostly hated me, but still. (Got my certification, turns out somebody who doesn't grasp their field of expertise can't create documents that hold up in front of a judge)

oh good, complete strawmanning in the first 60 seconds, this should be fun

Uhm i think there are some thing wrong... super35 has a cropfactor of 1.6x but and is 24mm wide but there are many variations alexa mini has a cropfactor of 1.27x some other sensors have 1.5x...and fullframe is 35mm and has a cropfactor of 1x. The alexa 65 has a crop factor of 0.7x

There’s an easy way to learn this. Pick up an older digital SLR camera versus a full frame camera. Shoot them side-by-side with the same lenses. The problem with the smaller sensors is that in order to get the same or relative field of you need a back up. Depth the field revolves around four factors, one of which is distance the subject. The best way to learn these things are just to shoot with various sensor sizes and be willing to learn. Most people will never understand these concepts while they stand and argue their points while holding the cellphone camera. The farther away you get from those people - the smaller they will appear.

Love your videos, but there’s lots wrong with this one. Crop factor is measured at 1.0x when referring to 35mm stills film, not super 35 motion picture film. This is a major difference as 1.0x size sensors are actually Full Frame sensors such as the FX3. This means that S35 cameras such as the Alexa mini have a crop factor of approximately 1.25x or 1.33 with a camera such as the Komodo. Compression is also defined completely incorrectly in the video. Crop factor does in fact changes the perceived focal length of an image, and compression is directly affected by the perceived field of view of a lens, rather than the lens itself. Therefore, a 50mm lens on the Alexa mini, will give the exact same compression as a 65mm on the mini lf, assuming they are both in their open gate modes, or a 22mm on S16 (1.66) film. The only real difference that larger sensors give you, is higher pixel pitch at the same resolution, and a perceptually shallower depth of field when at the same field of view with the same T stop

COMPRESSION

These comments should be addressed in another video. It would make for good knowledge sharing and be better for the community.

Oh this one is gonna trigger tons of folks. 😂

Another major mistake, the crop factor only applies to filed of view but not focal length, regardless of sensor size, a 50mm is a 50mm, regardless of field of view, all sensor shares same perspective, thus regardless of sensor size, you never say that a 90mm on bigger sensor looks exactly the same as a 50mm on smaller senor

Might be better to discuss the difference between Super35 and 35mm...

I wish you didn't add fuel to the fire of missinformation about compression and I'm quite baffled that someone like you doesn't understand it. Otherwise it's very informative video.

Nobody who has any idea about what they're talking about thinks that crop factor is the only difference in sensor sizes wtf?

I though that crop factor was 1x on 35mm full frame sensors, not s35 ones

all the crop factor tells you is how close or far away you’ll have to put the camera to use the same lens.

It's funny because in the videography world (indie filmmaking...etc) the standard size is Full-Frame. So that S35 sensors are considered 1.33 or 1.50 crop factor.

Hope everybody is aware that same F-stop with same crop on the subject (for example portrait) will have exactly the same depth of field regardless the focal length. Only thing changing is background compression which gives an illusion of "more bokeh". Same F-stop on different sensors will create different DoF ... This video is kinda misleading IMHO ...

La cantidad de pelotudeces que tengo que ir a leer en los comentarios, mamita querida!!

Wrong.

S35 ≠ Crop Factor 1x 35mm AKA Full-Frame = Crop Factor 1x

This is close but not quite right. Gerald Undone has a good video explaining the nitty gritty of crop factor, and Tony & Chelsea Northrup have a good video demonstrating an easy formula for applying crop factor to not only focal length but to F/T-stop (regarding its effect on DoF). Even a formula for ISO. But as a cinematographer shooting on a native ISO sensor, all you have to remember is to multiply both the focal length and the T-stop by the crop factor to get the equivalence (and then adjust your NDs or lights accordingly, obvi) if you're going to swap out lenses for the same FoV. In this case, a T/2.8 on Super 35 is more like an T/1.8 on Full Frame-not directly because of sensor size, but because if, when switching to a smaller sensor, you're changing to a wider lens to keep your FoV and distance from the subject the same, then your lens diameter at T/2.8 is going to be narrower than it was on the longer focal length when that one was set to T/2.8. So you'll have to open up to roughly T/1.8 to get the same DoF. If that isn't confusing lolol

Gerald the purple need to see this..

Wow. Lots of mistakes in this video. I'm surprised you did what seems like a lot of research and editing but there are quite a few errors. Others have mentioned them.

You can use T1.3 lenses on S35 - go learn how to light better and stop arguing about sensor size.

You need to leave this video up. Your engagement is going through the roof with all the people correcting the factual errors!

No esta correcto este video !

How does everyone who talks about crop factor fail to bring up anamorphic?

this is just straight up misinformation from the beginning, please redo

Bro got roasted in the comments 💀

This video is racist AF. 😳

Yeah... that's not how it works. Nice try though!

Why does this guy talk this way? With a 10-word “sing along” cadence. Fantastic information, but the vocal style drives me away after a few minutes. The inflection pattern is amazingly regular, like a droning sound. Sorry…