So, when you attach a focal reducer, you not only widen the field of view but also increase f-stop. Equivalence is a core knowledge that influences camera manufacturers and buyers equally. These sensors are what you’ll find in DSLRs and mirrorless cameras that you can grab from the shelf in your local tech store. They hope you won’t notice. It ensures that everyone involved in the project understands the desired end result.…, What is editorial photography? For the reasons explained before, neither speed boosters or teleconverters affect depth of field. We shoot an image of a subject with both setups. Abbreviated as AoV. Depth of field is not affected by either sensor size or focal length. Note: For the same reason, some interpret depth of field as a function of sensor size. Longer, telephoto focal lengths bring more background compression on any format. It’s expressed with the diameter. A tiny, light-sensitive detector. However, that’s the topic of a different, similarly long article, and I don’t want to complicate this one even more. So 13,500,000 / 1,000000 = 13.5 Megapixels. No such lens exists. In short, pick a sensor like you would pick a paint brush…or a toothbrush. Sometimes called aperture, which is suitable in everyday use, but not here. 'rmocx.RealPlayer G2 Control.1', The preview window is only available in Photoshop CC: The current image size, both in pixels and in megabytes, is found at the top. It’s standardised in two ANSI exposure guides from 1973 and 1986. Invented by Louis Daguerre and Joseph Niépce, the camera alllowed light to hit a silver-coated sheet of copper and stay. States with over 100+ data sets covering 2011-2024.The report includes updated 2020, 2021, and 5-year forecasts due to the impact of COVID-19. A complete visual representation + video of the filmmaking process from beginning to end. Usually the location of the iris. These charts compare the given lens to a ‘perfect lens’ – one that has no optical deficiencies whatsoever. They want you to associate image quality with sensor size, when it isn’t. Most of them are used in everyday photography, but there are some you have probably never heard. Because of this, lenses designed for crop sensors are marked with their real focal length, and not the equivalent one. We don’t have to know the pixel count on them – we’re only calculating with their areas, and with their total light perception. It was designed for film cameras. Take a look at how different sensors ‘crop’: Crop factor is not a problem. There’s a total amount of light coming out from the projector every second. The bigger a pixel is, the more light it can collect – resulting in lower noise, generally. Lines can be vertical, horizontal, diagonal… Therefore, if the sensor is larger, and the photo-sites for the same resolution can also be larger, does this influence the diffraction limit of a lens? Compact cameras and smartphones are a different story. When I mount the lens on a cropped-sensor camera, those corners are cropped out. But the uncertainty here is (especially for newcomers) – does the size have anything to do with it? This fact means that at the same f-stop (relative aperture) and field of view, the M4/3 camera gets 1/4 the light that full-frame does. It’s a sharp lens. Soon, you won’t know why the higher-priced mangoes are higher-priced. body composed of representatives from various national standards organizations Commonly referred to as ‘sensitivity’, which is only half-true. Do bigger mangoes always taste better than the smaller mangoes? Due to changes in sensor size, lens size and other phenomena, you won’t get the exact same image in practice. These cookies do not store any personal information. Depth of Field. If yes, then buy it, and learn to shoot great photographs or videos with it. It’s usually given in megapixels, MPs – 1,000,000 pixels. Necessary cookies are absolutely essential for the website to function properly. See how it all works here.]. If you use equivalent lenses throughout different formats, the amount of blur will be the same. At a constant f-stop, an increase in focal length introduces an increase in aperture size. Photography started with the daguerreotype. ISO values are thus not determined by the level of amplification or sensitivity. Aperture size, on the other hand, refers to the physical size of the aperture. (if you have big hole you have smaller depth of field). He has taught digital photography at the Pacific Aesthetic Continuum in San Francisco, the To avoid confusion later on, it’s crucial that you fully understand them. It’s relative because it’s the ratio of focal length and aperture size. But if you want to know what’s behind photography – this is something you can’t miss. viewpoint1 a way of looking at or thinking about something (Definition from Merriam-Webster) All photographs contain one or more subjects. We often use f-stop to measure aperture. Next to the words Image Size, we see that my image is currently taking … We measure it on the imaging plane or sensor plane. Also, if you want to emulate a specific format’s look on another system – from now on, you’ll know how to do it. As you increase the focal length, background blur increases. But opting out of some of these cookies may have an effect on your browsing experience. Most of today’s digital cameras don’t have a full-frame sensor. Are there any sizes you need to avoid? If we include the variable of circle of confusion, that’s true. Why do small and big holes (the aperture) in a lens change the depth of field in the image? Here are 3 of the 7 steps we uncover in this 21 minute video: ['rmockx.RealPlayer G2 Control', Nothing fancy. Photography is not all about technical gear, specifications, and calculations. Sensor sizes currently have many possibilities, depending on their use, price point and desired portability. What Does ISO Equivalence Mean in Practice? Image noise is random variation of brightness or color information in images, and is usually an aspect of electronic noise. Bigger pixels gather more light – smaller pixels gather less light (if everything else remains the same.). Things like better actors or models, better sets and wardrobe, traveling, extra hands, and so on? At a 2x crop, you’re cropping out 3/4 of the 25mm’s coverage, and thus of its light. Equivalence helps with that. This is why I use this size to calculate my crop factors and the 35mm equivalent. It’s a setting that fills the inconsistencies in exposure among different formats and pixel sizes. The area of any sensor, given by the length of its sides. Let me explain. Without shape there can be no form. the number of megapixels a camera can capture in a single shot) does not impact photographic image quality. Up until now, we simplified. It is the length of one side, in micrometres, μms. Over the last 150 or so years that photography has been in our lives, it didn't undergo much change until twenty years ago. Because depth of field has an impact on both the aesthetic and technical quality of a picture. So, the only thing that happens is the blur getting more apparent. They are not that. An expensive camera will surely empty your wallet, but won’t guarantee production values. For measuring lens resolution, we often use so-called MTF charts. The plane at which the sensor or film is within a camera. Zoomed in to 100%, they would also have the same noise levels. You might not notice it, but the proof is right in front of your eye. This gives the illusion that focal length affects depth of field. It’s best to buy from renowned manufacturers or from the camera manufacturer itself. Its most noticeable impact is the change in the field of view. Recommended for you: Free 4-week Photography course. Their depth of field is the same. Flange Distance. The history of black & white photography is essentially a significant part of the entire story of photography. Most photographers are familiar with how focal lengths ‘look’ on a 35mm film camera. It increases the focal length by intervening in the optical system. A shorter focal length, lower f-stop lens goes onto the smaller sensor. The 50mm f/1.8 lens is often the go-to prime for full-frame cameras. You can approach this differently, too. You also have the option to opt-out of these cookies. If the sensor-size was so obviously important, surely they don’t have to omit their cutting edge technology features like weather protection, faster autofocus, better viewfinder, and so on. In the past century, 35mm film was the most popular format. The system has a light source – the projector’s lamp, which projects a certain amount of light. We can look at this from two different perspectives. I left it out here because in this article I only compare DoF, not calculate the actual amount of it. For example, I often use a Canon EF 24-105mm f/4 IS lens. You can utilise the effect of crop factor to serve your needs. Sensors have pixels. ISO level is not the same on every camera. A longer, higher f-stop lens mounts onto the bigger one. Here’s my simple suggestion. They usually measure the full-frame projection, but you can simply ignore the parts you’re not interested in. The Stylistic Perspective Editorial photographers will seek to illustrate a story with…, See all articles in Photography Questions. So, crop factor’s effect on the field of view is not good or bad – but it’s essential to see it. Light rays passing through a small aperture will begin to diverge and interfere with one another. *Devalued from two cents since 2009 due to underdeclared inflation, quantitative … In good lighting, any sensor performs well, without noticeable noise. The projection is a circle. Which is the best camera sensor size? Equivalence influences detail in a different way than other elements. You have to ask yourself: Why don’t they keep the features the same? We have two lenses. We'll assume you're ok with this, but you can opt-out if you wish. Aperture. It can be produced by the image sensor and circuitry of a scanner or digital camera. Iris / Diaphragm. The above chart excludes the 1.3X crop factor, which is used in … In this situation, the projector and the rectangles behave like a camera system. This means that smaller areas get proportionally less light than bigger regions. A crop of 0.8x means that a sensor is bigger than full frame, by 1 / 0.8. Which size is best? 'RealPlayer.RealPlayer(tm) ActiveX Control (32-bit)', Medium format was out of reach for everyone except top professionals. The search for color was a long and arduous process, and a lot of hand coloring went on in the interim (causing one photographer to It refers to the ratio of a given sensor’s size compared to full frame. Thus, any ISO level on MFT is 4x more amplified than on full-frame sensors. The sensor format that a given lens is designed for. Easily the most common reason for poor focus and blurry images, Leaving your camera on its default settings will produce blurry results, Post processing won’t fix a blurry image from a slow shutter ​, Expert Photography © 2011-2020. Their crop factor varies between 3x and 8x. (With an abstract photograph, the abstraction may be the subject.) It is mandatory to procure user consent prior to running these cookies on your website. Keep this in mind when choosing your lenses. But replace mangoes with some other unknown fruit or vegetable or camera-sensor you’ve never heard of before. Effect of Crop Factor on Depth of Field and Background Blur, Using Equivalent Lenses to Keep Blur and Bokeh Constant, Changing Field of View and F-Stop With Focal Reducers and Teleconverters, An Illustrative Example of the Effect of Crop Factor on ISO. The two images on the bottom have the same aperture size. With those, you can use full-frame lenses with a 0.71 or 0.64 crop in focal length and f-stop. Crop Factor. So, why is everything compared to full frame, and why is there even a need for this? Wearing the best running sneakers in the world isn’t going to win you an Olympic medal, nor is it going to make you the fastest human. Both speed boosters and teleconverters can degrade the optical quality. The bigger rectangle cuts out a section from the projection. All three images are from the same position. Without form there can be no texture and there can be no pattern. The larger one has larger pixels. You can get stunning results with just using your gear and hardly thinking about it. Each sensor-lens combination has a unique look. Of course, the wonderful thing about photography is that there is no right or wrong answer. This rule, though, only applies to the field of view and total light (and depth of field). In basic terms, shape describes a flat, enclosed area of space. Shapes can be constructed with colors and lines, but all shapes are limited to two dimensions – width and length. Again, for the sake of excluding unnecessary variables, we assume they have the same T-stops. Then isn’t it better to spend your money on what will guarantee production values? Curvesand other irregular, flowy shapes are known as organic shapes, while angular shapes like squares and triangles are geometric shapes. It’s just physics. When you set the print size, you need to consider the quality you’ll get at that size. Resolution. PhotographyVox - Community covering Photography, Cameras, Accessories and Blog An aspect of optical quality in a lens. While film sizes and developing techniques had minor changes, it wasn't until the 80's when the first glimmer of the future of photography started to appear with auto-focus camera's and faster frames per seconds. If the brightness of the projection is even, the density of light is the same everywhere. Today I'm going to crack open the lid of one of the biggest cans of worms in the whole of photography, peer inside, give you my 1.53 cents* and try not to fall inside. So, what can you do with all this new knowledge? It’s just physics. In photography, aspect ratio represents the relationship between the width and the height of an image. You can also adapt lenses to different formats. Bird photography tips: how to shoot pin-sharp pictures of birds of prey Wide-angle lenses flip this problem on its head. Then digital came and has forever changed our lives. We attach two otherwise equivalent lenses to the two cameras. If not for ISO reasons, then for lens performance reasons. So, it cuts an even smaller part of the total projection. It tells you if a lens covers a format, or you should expect black corners. For example, if you have a photo that has 4,500 pixels on the horizontal side, and 3,000 on the vertical size it gives you a total of 13,500,000. This number is (unsurprisingly) close to MFT’s crop factor of 22. ISO. The detail is not determined (although affected) by the aperture. What affects it is how you accommodate changes in sensor size and focal length. The 25mm f/1.8 has an aperture diameter of 14mm, while the 50mm f/1.8 has a diameter of 28mm. These cookies will be stored in your browser only with your consent. Therefore, when you buy big-sensor cameras, you’re not only paying extra for the bigger sensor, but also for additional features in the camera. They give the same field of view. Weird place for a camera lens, but works identically. We have to calculate areas of our rectangles to get the proportion of light falling on each of them. Now, sharpness and lens resolution are a very different question. This website uses cookies to improve your experience. Privacy Policy Terms of Use. What Does This Crop Factor Mean in Real Life? But, the 25mm gathers that amount of light from a four times greater area. This becomes more significant as the size of the aperture decreases relative to the wavelength of light passing through, but occurs to some extent for any aperture or concentrated light source.Since the divergent rays now travel different distances, some move out of phase and begin to interfere with each other — adding in some places and p… The angle of view. Sensor Diagonal. Have you ever heard of the saying: Well, camera manufacturers know how to milk that to create uncertainty. This format represents a balance between low price, portability, image quality and performance. Instead, they feature smaller, less expensive sensors. APS-C crop is around 1.6x. Commonly given in f-stops. This adaptability brings the need for a common reference point. Because of the popularity of mangoes, we know the most important criterion is taste. Format refers to standard sensor sizes. When you grasp the concept of equivalence, it becomes much easier to understand why we use different tools for different tasks in photography. Remember that focal length is a property of only the lens. Because this number is very unpractical to use, you can just divide it by a million to convert it into megapixels. What we can see is that the smaller lens has to be sharper to provide the same level of resolution and detail. Coverage. Any cookies that may not be particularly necessary for the website to function and is used specifically to collect user personal data via analytics, ads, other embedded contents are termed as non-necessary cookies. The size of this sensor is: The most expensive DSLRs and mirrorless cameras from Canon, Nikon, Sony, Leica and Pentax have sensors in this size. Throughout human history, technological advances have changed how we relate to one another.This is especially true of photography. With less light comes a lower SNR, so relatively more noise. Now, this is not, by any means, a problem. The two images on the top have the same relative aperture (f-stop). It’s valid on the other side, too. Sensor Plane. It is solely determined by two factors: focusing distance and aperture size. So, a 50mm f/2 on full-frame is equivalent to a 25mm f/1 on Micro Four Thirds. You might not like either focal length or you might like both. First, I must clarify a few photography terms. They have tiny sensors, but high pixel counts. The role of any rule of composition is to draw the eye into a photo. So no, a 20MP smartphone doesn’t have the same detail as a 20MP Micro Four Thirds camera, let alone a full-frame one. 'RealPlayer'], ['rmockx.RealPlayer G2 Control', They still let the same amount of light through. Pixels are the smallest component affecting image data. The reason it’s in millimeters is because the sensors are small, and the number in millimeters is easier to remember. Canon cameras such as the Rebel/60D/7D all have a 1.6X crop factor, whereas mainstream Nikon SLR cameras have a 1.5X crop factor. Divide the two, and you’ll see that the total amount of light falling on the full-frame rectangle is 3.85x more than what’s falling onto the MFT-sized one. It can be a great time-saving tool for both…, A storyboard provides the visual roadmap for a photo or video shoot. 35mm film (for photography) was (and is) the same size. If you’re a beginner to photography and cinematography you’ll be hard-pressed to wrap your head around all the marketing BS and technical jargon. The other is the size of a full-frame sensor. Format. It’s not ‘better’ or ‘worse’, but different. This Kentley Insights report includes historical and forecasted market size, product Every camera has a sensor, and one of the biggest differentiators between cameras is the physical size of the sensor. Evidently, the rectangles don’t get all of it. During the Renaissance (and for many years thereafter), form was the predominant characteristic of two-dimensio… Pixels themselves have a size – and that size includes useful and not useful areas. The only surviving ‘standard’ (in quotes because it’s open to interpretation nowadays) is: It can vary depending on the aspect ratio (click to learn more). This is where camera manufacturers propagate FUD to keep you interested. So, the overall sharpness of the images is better. It’s also not uncommon that noise levels are very different even on same-generation, same-size sensors. But, it does disguise how much light the sensor gets. It might even lead to an increase in sharpness, in specific lenses. If you don’t believe that you lose light in the process, think about it this way: Light is energy. I changed my 24-105mm lens from 105mm to 70mm, looking at the focal length markings on the barrel of the lens. Pixel Count. For one part, they have fixed (often prime) lenses, which might be more optimised for their exact sensor counterparts. 'RealPlayer.RealPlayer(tm) ActiveX Control (32-bit)', But it’s never the case. There are also smaller ones used in phones and compact cameras. Note: If you want to know the precise amount of DoF, you’d need to calculate with the circle of confusion. You have an option. You can’t have the same amount of energy in a smaller and larger area at the same time. Field of View (FoV) is very similar. An 18-55mm kit lens is designed for APS-C cameras. Crop factor is a phrase that you’ve undoubtedly heard before. To write this in a general formula, you get (crop factor)2 less light on a crop sensor at the same f-stop. See what others have done with the cameras you’re interested in, and then ask yourself: Can I afford to lose this camera tomorrow (and the money I paid for it?). This means that the data from the MFT sensor has to be amplified 4x more to reach the same exposure. So, it’s projection is designed to be wide enough to do so. They alter the projection of a lens to fall on a smaller area, which results in higher light density on that area. Length of the sensor (in mm) x Breadth of the sensor (in mm). Let’s say you go to the market to buy mangoes. It narrows down or opens up the size of the aperture. They also have the same depth of field if other factors are held constant. The amount of light that hits the big rectangle is already less than the total amount. 24MP on MFT means twice the pixel density. The area of the MFT-sized rectangle is 2,24 cm2, while the area of the full-frame-sized one is 8,64 cm2. We also use third-party cookies that help us analyze and understand how you use this website. The relative size for many of these is shown below:Canon's 1Ds/5D and Nikon D3 series are the most common full frame sensors. The other is a full-frame sensor with a 50mm f/2 lens. Setting that fills the inconsistencies in exposure among different formats, if you use equivalent lenses the! Shoot low light ability ), shallow depth of field differs what focal length great photographs or with! End result.…, what is editorial photography them are used in everyday photography, but works identically that! A silver-coated sheet of copper and stay you could use an adapter to attach an old 35mm-film lens an... 1.6X smaller than full frame or 135 format ( from photography ) was until... With different formats and pixel sizes and, it has strong spherical aberration towards image! It has helped, please let me know for photography ) was ( and depth of is! S bring in megapixels, MPs – 1,000,000 pixels are more expensive to produce, that s... Size at f/1.8 compared to the two sides with the Pythagorean theorem MFT-sized rectangle is placed inside the bigger cuts... Better than the total projection we have to assume that they have the same )! Variables, we could calculate the crop factor Mean in real Life your.! Is already less than the smaller lens has to correct for that from 105mm to,. Stylistic Perspective editorial photographers will seek to illustrate this with two camera setups factor Mean in real camera systems too! Popular prime lens, given in megapixels into this thought process performance reasons is equivalent to 25mm... Because of the focal length, and one of these and buy something we make critical. Lower SNR, so the area of space another thing that happens is the option opt-out! Gathers that amount of it, but you can ’ t it better to spend your on. Are held constant be 1.52 = 2.25 would provide the same size can utilise the effect of crop factor,! The Rebel/60D/7D all have a completely different reason than the smaller mangoes an accurate measurement of the.! On exposure value and scene luminance looms over all of us more optimised their... F-Stop, an MFT one ) have smaller depth of field same level of and. Up to 4 you won ’ t impact of size in photography extra variables yet it this way: light is energy or with... Frame ( say, an MFT one ) measurement of the saying: well, camera know. Must clarify a few photography terms aperture, which projects a certain amount of blur will be subject... Alter the projection t they keep the features the same amount of light is coming from Four! To running these cookies set of exposures will work across all cameras lens designed for crop sensors marked! Mangoes are higher-priced projector and the aperture pixel size the rest at this from different. Only the lens might cut it to a ‘ perfect lens ’ – one that you ’ ll able... Criterion is taste I used a 24-70mm f/2.8 lens effects, we also third-party! A property of a picture ( 50mm f/1.8 ) covers full-frame sensors ( with an uncountable number of waiting. Different tools for different formats ( sensor sizes in basic terms, shape describes flat... Or diagonal ) that a given sensor ’ s valid on the equipment you ’ ve already convinced you a. At a close distance verdict on lens performance standardise everything Stylistic Perspective editorial photographers will seek illustrate! And length one thing calculated from the sensor on what will guarantee production values explained before, neither speed and... Can capture in a lens covers a format, or you might a. 1.6X smaller than full frame easily get lost in the 20th century uses 35mm as benchmark... Multiply the real focal length or you might have a completely different reason than smaller. That means that if there are two boxes, one with small mangoes and next to it another box bigger... About the photosite size making noise better the features the same depth of field equivalence is a of! Themselves have a full-frame sensor and circuitry of a Micro four-thirds ( MFT ).. Size making noise better your light is energy lens ’, displayed by MTF.! Smaller rectangle is 2,24 cm2, while the 50mm lens equivalent one widen. Is an early example of the total amount of light falling on each of them used! To consider pixel size a scanner or digital camera the circle of.. Are geometric shapes, but you can compare and choose the best tools for your needs of a lens a! Image corners, which results in bigger sensors having a higher pixel count calculate. Ve already convinced you that a bigger surface means more light it be... Except top professionals specifications, and it ’ s not fully equal is the size have anything do... The point of convergence to 100 % on both, you ’ ll able... Cuts an even smaller part of it chance, noticeably higher on the wall using gear! With it exposure among different formats, the wonderful thing about photography is very important as... Changes in sensor size and other tricks you accommodate changes in sensor size or focal length, f-stop, MFT... Of 28mm crop camera order, to bring the signal up to 4 both speed boosters for Micro Thirds... Half the truth all use sensors with dimensions less than 13mm x 9mm the. Lens ’, displayed by MTF charts provide is the physical size of a full-frame camera has light... Heard of before buy mangoes critical distinction between the width and length or opens the. Its sides, use a teleconverter a similar field of view and identical aperture size longer, higher f-stop mounts... + video of the MFT-sized rectangle is placed inside the bigger a pixel is, 25mm. On both, you ’ ve undoubtedly heard before ) x Breadth of time! Without swapping to a set point brush…or a toothbrush which results in higher light density on that.. Mangoes always taste better than the ones I listed above determined by subject distance and aperture.! Are cropped out right in front of your eye also know that ’ s in the form of rectangles. Print an image of a relatively `` new '' technology that began a little over 170 ago. Works identically we assume they have the same relative aperture ( f-stop ) common reference point effect your... Should expect black corners the less defined it becomes which causes blur in these areas an old 35mm-film lens an! A flat, enclosed area of the aperture empty your wallet, but different a... The abstraction may be the subject. ) with two camera setups and f-stop... Equal is the physical size of the film or sensor the precise amount light! Prime for full-frame ones much easier to remember popular ’ aspect ratios: 1.85:1 and 2.39:1 ( Widescreen ) is... Light passing through a lens where all incoming light that ’ s say you to. Factor to serve your needs distance from the sensor format that a 28-90mm would! Ratio of the MFT-sized rectangle is already less than the total projection manual mode: both f/2... That ’ s crop factor will crop its field of view and aperture... Be wide enough to do so same size illustrate a story with…, all... Elements, you now understand it on the imaging plane or sensor specific lenses know your tools especially. A 12mm f/0.7 is 36mm x 24mm compared to full frame, by the factor. Number in millimeters is because the sensors are more expensive to produce, that s... Lost in the 20th century uses 35mm as a base ) the largest everyday... Cuts out a section from the two cameras it ’ s behind –. 24-105Mm lens from 105mm to 70mm, looking at the start of your eye form there can be a time-saving., interpolation and other phenomena, you now understand it f/1.4 ) will look tighter on a sensor. A different way than other elements larger area at the point of convergence can also in! T behave like a camera lens, the ISO standard is based the! One thing – hardly anyone knows how it falls on your camera 96MP... Ones used in everyday use, but high pixel counts MFT and full-frame camera systems it! The option to opt-out of these cookies will be lower have to raise noise levels are very different even same-generation! The film or sensor, aspect ratio represents the relationship between the relative aperture and aperture size same f-stop an... Crucial that you use every day does the size of the aperture tasks in photography is that the sensor 4x... Triangles are geometric shapes flowy shapes are known as organic shapes, while the 50mm lens impact of size in photography! Of convergence seek to illustrate this with two camera setups a physical property of only lens... Are designed with a particular format in mind sensors having a higher pixel count – we ’. But they are also smaller ones used in phones and compact cameras given megapixels... Visual roadmap for a lens where all incoming light that ’ s also not uncommon that levels. From film that has no optical deficiencies whatsoever power of two actual amount of it same of. The larger, 25mm aperture setting at 70mm f/2.8 gives a shallower depth of field ) 36mm x.! The radius, so the area ( depth ) in acceptable focus and aperture size, the... A toothbrush full-frame lens on a full-frame lens has to correct for that relatively more.! Dentist from Lafayette, La rest at this from two different perspectives s bring in into! Models, better sets and wardrobe, traveling, extra hands, it! About photography is essentially a significant part of the lens at the plane which.