Fellow Photographer,

I originally created the calculators on this page for myself as an exercise while learning to write javascript code.

This was way back in the early days of the web when it was common to "give something back to the online community" so I decided to share these as my contribution. I added a simplified explanation of depth of field and posted the page to the Outsight web site.

Little did I suspect how popular this page would become! Over the years, I've received countless DOF questions and frankly, have learned far more than I need to know trying to answer a few of them. There's been numerous expressions of gratitude (you're welcome!) and requests for more information or features too - the equations, more film formats, accommodating digital cameras, printable charts, etc.

Hence, the page here for you today. I hope you find it useful. Make your own DOF charts for field use using the original calculators. Use the equations and create your own calculators in a spreadsheet or other application. Or use the Chart Makers and quickly print customized depth of field charts.

Wishing You Great Light & Good Shooting,

- Tom Hallstein

Focus Pocus
Depth of Field Calculators
For Digital and Film Cameras


Have a Digital Camera?
Before using the basic calculators on this page or the Chart Makers for a digital camera, you must determine your digital camera's Lens Multiplier Factor (LMF) which is simple to do.

Hyperfocal Calculator
Use this calculator to find the maximum focus range, or hyperfocal, for any aperture and lens focal length combination. I carry a list of hyperfocal settings for commonly used f-stops and focal lengths for my zoom lenses that don't have depth of field guidemarks.

Hyperfocal Distance Chart Maker
Quickly customize, create, and print charts of hyperfocal distances for any ten apertures and ten lens focal lengths. Select distance units in feet or meters. Choose from seven film formats or use the LMF for your digital camera. The Chart Maker instantly creates concise, easy to read tables with this valuable information. Just print them and you're done!

Focus Limits Calculator
Doing critical close up work? Selective focus? Here's a handy tool. Enter either the aperture and focus distance to determine near and far focus limits, OR enter near field and far field limits to determine f-stop and focus setting... if it's possible!

Focus Limits Chart Maker
Quickly customize, create, and print easy-to-read charts showing near and far focus limits for a single focal length at any ten apertures and ten focus distances. Select distance units in feet, inches, meters, or centimeters. Choose from seven film formats or enter the LMF for your digital camera. Shows hyperfocal distances too. Essential information for your camera bag.

Depth of Field?
Here's a quick explanation if you don't know what this is.

The Equations
For the mathematically inclined...


Hyperfocal and Depth-of-Field Calculator

The hyperfocal distance is the focus distance that yields the greatest depth of field, or range of apparent focus, and will be from one-half the hyperfocal distance to infinity.

note 1: Calculation based on adequate focus for an 8x10 inch print viewed at arm's length. (Long considered the standard for depth of field.)
note 2: For digital cameras, enter actual lens focal lengths, not 35mm equivalent focal lengths.


Select Format:
35mm  6x6cm  4x5in  Digital LMF :
Enter Lens Focal Length:
mm (millimeters)
Enter Aperture f -stop:
Focus at feet for Depth of Field from feet to infinity.
(multiply feet by 0.3048 to convert to meters)
For more film format options and the ability to quickly customize, create and print concise, easy to read tables of hyperfocal distances, check out the Hyperfocal Distance Chart Maker.


 
Focus Limits Calculator

Enter aperture and focus distance to determine near and far focus limits or enter focus limits to calculate aperture f-stop and focusing distance.

note 1: Calculations based on adequate focus for an 8x10 inch print.
note 2: Focus distances over several thousand inches can be considered infinity for most purposes.
note 3: When solving for f-stop and focus if aperture result is unrealistic enter smallest aperture available and recalculate for near/far limits - reiterate as necessary - but there are limits!
note 4: For digital cameras, enter actual lens focal lengths, not 35mm equivalent focal lengths.


Distance units are in inches
(1 inch = 2.54 centimeters)
Select Format:
35mm  6x6cm  4x5in  Digital LMF:
Enter Lens Focal Length:
mm (millimeters)
Enter f-stop & Focus Distance to Calculate Focus Limits
- OR -
  Enter Focus Limits to Calculate f-stop & Focus Distance
Enter Aperture f-stop:
Enter Focus Distance (inches):
 
Enter Near Focus Limit: inches
Enter Far Focus Limit: inches
Depth of Field: inches
Technical Note: The focus calculators assume a simple, single element lens with the focus distance measured from the center of the lens to the object. In reality, most lenses have multiple elements and we assume that the focus distance is from middle of the lens assembly (lens barrel) to the object. But at close focus this may be inaccurate because there can be several Principle Points of Focus. Precise close-up focusing requires determining these Points.
For more film formats and distance unit options PLUS the abilty to quickly customize, create and print concise, easy to read tables of focus limits, check out the Near - Far Focus Limits Chart Maker.


 
What is Depth of Field?

Knowing what will appear to be in focus (and what will be out of focus) is one of the most basic considerations when making any photograph.

Although exact focus occurs only at the precise focusing distance, depending on film format or sensor size, lens focal length, aperture size and focus distance, the apparent range of focus, or depth of field, can vary considerably. Additionally the size of a print as well as the viewing distance will have an effect on this apparent depth of field.

It should be noted that an 8x10 inch print viewed at arm's length has long been considered the standard on which most lens manufacturers base their lens' depth of field guidemarks.

Without going into the physics involved, this apparent depth of field is due to an optical phenomena called the circle of least confusion. When an object is at the exact distance the lens is focused, every point on the object will focus to a point on the focal plane. When an object moves out of focus, on the focal plane these points begin to grow and become circles. The farther out of focus an object is, the larger these circles become. However, up to a certain point (again depending on film or electronic sensor size, lens focal length, etc.), these circles of confusion are unresolved by the human eye and the image appears to be in focus over a range of distances thus having 'depth of field'.


 
Determing Depth of Field for Digital Cameras

The same factors that affect depth of field in film cameras apply to digital cameras too: aperture f-stop, focus distance, lens focal length, format (essentially the size of the 'light recording area' whether a piece of film or an electronic sensor), and of course, the final print size (traditionally, 8x10 inch).

However, unlike film cameras which use a handful of standardized film sizes (35mm, 6x7, 4x5, etc.), digital cameras are being made with numerous different sized image sensors. This makes determining the all important Diameter of the Circle of Least Confusion parameter used in the calculations a laborious and ongoing task for each and every digital camera model! Fortunately, there's an easy "shortcut" that yields accurate results.

Lens Multiplier Factor (LMF)

In the specifications for the focal lengths of the zoom lenses in point-and-shoot digital cameras, most manufacturers also show an Equivalent 35mm Focal Lengths spec.

By dividing the Equivalent 35mm Focal Length by the camera's Actual Focal Length we derive a number, The Lens Multiplier Factor, that can be used to interpolate an acceptable Diameter of the Circle of Least Confusion for use in depth of field calculations for our digital camera.

For digital camera bodies that use interchangeable lenses the manufacturer usually specs this Lens Multiplier Factor. (A Nikon D300, for example, has a Lens Multiplier of 1.5, while Canon specs the EOS Rebel XS as having a Lens Multiplier of 1.6.)

Do the Math:

LMF =   35mm equivalent focal length    
camera's actual lens focal length
(LMF equals the 35mm equivalent focal length divided by the actual lens focal length)

Enter the Lens Multiplier Factor (LMF) for your digital camera into the
corresponding Select Format box on any of the Focus Pocus calculators.


IMPORTANT!
Be sure to enter your digital camera's actual lens focal lengths in the calculators.
DO NOT enter 35mm equivalent focal lengths!


Example:

In the specifications for an Olympus C-720, you'll see the zoom lens focal length spec is 6.4mm to 51.2mm. Right next to this is the 35mm equivalent focal lengths of 40mm to 320mm (Yikes! That's some zoom!).

Taking the wide angle equivalent 35mm focal length value of 40 and dividing by the digital camera's wide angle focal length of 6.4 we get an LMF of 6.25. Or divide the 320 (35mm telephoto equiv) by 51.2 (actual telephoto focal length); it's the same number: 6.25. Hence, an Olympus C-720 has a Lens Multiplier Factor of 6.25 and it is this number you enter into the Digital LMF box on the calculators.


Can't Find the Equivalent 35mm Focal Lengths for Your Lens?

If you can't find a specification for the equivalent 35mm focal lengths for your camera's lens, there's another method - if you know the size (height and width) of the sensor in your camera. First, determine the usable diagonal length of the sensor in millimeters (see note below). (Remember Pythagoras' Theorem? --- height2 + width2 = diagonal2.) Next, divide 43.3 by this diagonal length. This yields the LMF for this camera to use in the calculators.
LMF =                           43.3                         
Diagonal Length of Image Sensor (mm)

Enter the Lens Multiplier Factor (LMF) for your digital camera into the
corresponding Select Format box on any of the Focus Pocus calculators.

Important Note about Diagonal Length of Sensor: In investigating this approach, I discovered that the size many manufacturers spec for image sensors is not necessarily the portion of sensor area that is actually used to record the image. This makes this method highly suspect! If you determine the LMF for your camera this way, be aware that it most likely will be a very conservative number, meaning the usable depth of field available may be greater than the calculators indicate.


 
The Equations

Note 1: Based on acceptable sharpness for an 8x10 inch print.
Note 2: Multiply Inches by 25.4 to convert to Millimeters. Divide Millimeters by 25.4 to convert to Inches.

Hyperfocal Distance
Setting focus at the Hyperfocal Distance gives maximum depth of field from H/2 to infinity.

H = (L x L) / (f x d)

Where:
H = Hyperfocal Distance (in millimeters)
L = lens focal length (ie, 35mm, 105mm)
f = lens aperture f-stop
d = diameter of circle of least confusion (in millimeters)
      for 35mm format d = 0.03
      for 6x6cm format d = 0.06
      for 4x5in format d = 0.15

Near Focus Limit

NF = (H x D) / (H + (D - L))

Where:
NF = Near Focus Limit (millimeters)
H = Hyperfocal Distance (in millimeters, from above equation.)
D = lens focus distance (in millimeters)
L = lens focal length (ie, 35mm, 105mm)

Far Focus Limit

FF = (H x D) / (H - (D - L))

Where:
FF = Far Focus Limit (millimeters)
H = Hyperfocal Distance (in millimeters, from above equation)
D = lens focus distance (in millimeters)
L = lens focal length (ie, 35mm, 105mm)


Calculators Courtesy
Thomas Hallstein / Outsight Photography

PERSONAL USE ONLY
no commercial or redistribution rights granted