The depth of field calculator allows you to find the depth of field of any lens aperture at any distance. It also includes a 35mm equivalency calculation to see a given aperture’s equivalent lens crop and depth on smaller or larger sensor cameras compared to full-frame 35mm. For a deep dive into sensor size, see our APS-C vs Full Frame guide.
Depth Of Field Calculator
This calculator is built with the industry numbers for each sensor size’s general circle of confusion. The numbers come from viewing a printed photo at a normal viewing distance, not the 100% crop of an image.
This calculator is designed to give a general idea based on 24MP sensors. So, assume all sensors are 24MP regardless of the sensor type.
With the same lens, aperture and distance, smaller sensors show less depth of field in this calculator. That isn’t about pixels. An image from a smaller sensor has to be enlarged more to reach the same viewing size, so a smaller blur circle on the sensor already looks out of focus. That’s why each sensor size gets a smaller circle of confusion value.
Depth Of Field Calculator + Megapixels Adjustment Field
Since the Circle of Confusion is based on Sensor Resolution. I’ve added a different table allowing you to input the sensor megapixels. This gives you a more scientific depiction of the depth of field based on the resolution, but it isn’t necessarily real-world applicable.
The Circle Of Confusion
Circle of confusion = the disc or cone of light a lens produces that is considered acceptably sharp or in focus.
The Depth of Field calculator is based on a circle of confusion of standard photo viewing distances.
These are general numbers set by camera manufacturers. However, the value of the circle of confusion will change depending on sensor resolution and viewing distance. If you get closer to a high-resolution sensor, you will get better precision when discerning what’s in and out of focus.
Circle Of Confusion Sensor Values
Medium Format 645 = 0.05mm
Full Frame = 0.03mm
APS-C = 0.02mm
APS-C Canon = 0.019mm
Micro 4/3 = 0.015mm
1″ = 0.011mm
These values are adequate for calculations, but depth of field and resolution aren’t that simple, of course.
Sensor Size & Resolution
It’s best to use the circle of confusion values above when discussing the depth of field with different sensors and lenses, but there are some technical details that we can examine that will affect it.
Even though we use the circle of confusion to calculate the depth of field with different sensor sizes, the phenomenon is optical. CoC is set with sensor sizes because the detail is needed to see this CoC, and generally speaking, the larger film or larger sensor would give you more detail when looking at this CoC.
When we match the resolution of smaller sensors to larger sensors, weird things can start to happen. This is done by increasing the pixel density on the smaller sensor.
Printed images from smaller sensors have to be scaled up more when printing, which also increases the size of the circle of confusion.
Smaller sensors usually have a higher pixel density, giving a more detailed look at the cropped portion of the image the lens is projecting. This all plays a role in the overall perception of depth.
Blowing up the image increases the size of the circle of confusion, but increasing the pixel density improves its resolution.
Higher Resolution Sensors Have Shallower DoF | But Not Really
The ability to perceive the depth of field will also change the value of the circle of confusion. Higher-resolution sensors give more precision when looking at pixels that are in focus compared to pixels that are out of focus.
This technically means higher-resolution sensors will have a shallower depth of field because you will be able to see the exact point of focus falloff with more detail. Higher-resolution sensors don’t change the depth of field, but at the pixel level, they just let you see which pixels are in focus vs. out of focus.
So when you see someone say that higher-resolution sensors have less depth of field, technically they do at the pixel level, but optically it’s all the same: viewed at the same size, the background blur looks the same.
Some Practical Application
Take a 50mm lens at f2.8, focused at 10 feet. With the full-frame circle of confusion of 0.03mm, the depth of field is 24.42″. With the APS-C value of 0.02mm, it’s 16.19″.
The APS-C image with the same lens has a shallower depth of field.
A 50mm APS-C lens will have a cropped field of view of 75mm if you compare a full-frame 24-megapixel sensor to a 24-megapixel APS-C camera shooting the same image at the same distance. You’ll be looking at that 1.5x cropped depth of field of the APS-C image with a greater pixel density. The APS-C image has to be enlarged 1.5x more to reach the same viewing size, and that enlargement is what makes its depth of field look shallower with the same lens at the same distance.
We know this because higher-resolution cameras technically produce a shallower depth of field. After all, you get a more detailed view of the circle of confusion. However, if you were to stand back and look at the images in Lightroom without cropping in, the perceived depth would be the same.
For example, the Sony A7rIV has a 61MP sensor, but you can shoot in APS-C crop mode with 26MP. The depth of field with the same lens will never change if you’re shooting in full-frame mode or APS-C crop mode. However, if you used the same lens on the Sony A7III with its 24MP sensor shot in full-frame mode, you would see less resolution when cropped into the same field of view when compared to the Sony A7rIV shot in the APS-C crop mode and the APS-C crop with the A7rIV would have a shallower depth of field. The rendering would look the same, but you could see the point on the eyelash where the focus stops with the A7rIV.
Now, The Not Really Part
It’s a strange technicality, but this topic is often discussed. Smaller or higher-resolution sensors don’t really have a different depth since that’s completely analog and produced by the lens, but increasing the technology of the sensor is like adding more detailed notches on the ruler when it comes to measuring depth. This is likely why camera manufacturers refer to those standard circles of confusion values.
The Real Science Of Lens Equivalency
The above calculators are all based on a viewing distance and subjectivity of human perception and the assumption that we all have 20/20 vision. It also assumes that you increase the resolution as you move to a smaller sensor.
In reality, based on the physics of light, a lens projects the same image with the same focus falloff no matter what sensor you put behind it. An f1 lens doesn’t care about crop factor or pixel pitch, and it isn’t magically changing its cone of focus because of a different sensor. What changes is how much of that image the sensor captures and how much you have to enlarge it afterward.
How Printing Changes CoC
Printing, or scaling up smaller sensor images to match the same viewing size distance of larger sensors has the biggest effect on the depth and any sort of an optical anomaly because everything is scaled.
This is the biggest reason why larger sensor cameras are better; it’s not about the resolution. The resolution shouldn’t even be mentioned when comparing sensor sizes; it’s an irrelevant characteristic.
Images from smaller sensors have to be scaled more to match the same image from a larger sensor, resulting in a larger circle of confusion. Any flaws and imperfections are also enlarged.
Looking at Hard Numbers
If we were to shoot the Sony A7rIII full frame with a 50mm f1 lens focused at 10 feet, then shoot in APS-C crop mode with the same lens, we would have the same pixel pitch and the same circle of confusion but a 75mm-equivalent field of view.
So we could calculate in the maximum circle of confusion of the A7rIII, 2 x 4.51microns = 0.009mm.
Viewing at a close distance gives us the maximum circle of confusion value and a depth of field value of 2.59.”
That’s the shallowest depth of field you can measure on the A7rIII at the pixel level, regardless of viewing distance.
Now, we can do our APS-C crop with 18 megapixels, but since we don’t have any more megapixels to crop into, we can use the standard CoC given by APS-C sensors, which is 0.02mm with a 75mm crop factor.
This gives us a depth of field of 2.54″.
So the A7rIII full frame with its pixel-level CoC gives 2.59″.
The A7rIII 18MP APS-C with a standard CoC value produces 2.54″.
They are nearly identical.
Depth of Field Equivalency | Conclusions
A lens always produces the same depth of field regardless of the sensor you put behind it, but as you move to larger or smaller sensors, you will have to change your lens focal length or distance to match the perspective, and this will change the depth of field of a lens.
For real-world use, I added a 35mm lens equivalency and aperture value that would produce the same results at the same distance to help settle any confusion. You would have to adjust the exposure with shutter or ISO to compensate for the different aperture because no matter what camera you use, an f1 lens will always allow more light in than an f1.5 lens as long as the light transmittance value, the T-stop, matches the f-stop.
It also clears up the “bigger sensors gather more light” argument. Exposure is the same: f1 gives you the same brightness on any sensor. Where the idea comes from is total light. A bigger sensor collects more light overall at the same f-stop, so when you view a full-frame image and an APS-C image at the same size, the smaller sensor’s image had less light to work with, and that’s why it looks noisier at the same ISO.
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