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How to calculate DOF, hyperfocal distance

 

In order to make a picture such that 15 cm tall kingfisher just fits in the camera's longest dimension, you will need - besides patience and some luck - the right equipment: 

  • a camera with a full frame sensor and a 1200 mm telephoto lens
  • a camera with an aps-C sensor and an 800 mm telephoto lens
  • a micro-43 camera and a 600 mm telephoto lens


Cambridge in Colour
offers several calculation modules which help you answering questions like:

  • Which focal point do I need at a given camera and distance to a subject, to fit that subject  in the camera's longest dimension?
  • How large is the depth of field at a given camera, lens, aperture and focussing distance?
  • At which aperture setting starts sharpness to diminish because of diffraction?
Ijsvogel

Calculating Depth of Field

Depth of field is, in short, the area which is sharp in the photo. Depth of field is approximately dependent on the sensor size ("camera type"), the focal length, the aperture and the distance on which is focused. At Cambridge in Colour there's an additional, extended depth of field calculation, where also the size of the print, the viewing distance and the quality of your eyes are included in the calculation, for an accurate calculation of depth.

 DOF

Diffraction (circle of confusion)

Initially, your photos become sharper if you choose a smaller aperture. But at some point, the aperture is so small that light scattering (diffraction) occurs, making the photo less sharp again. Diffraction depends on the sensor size ("camera type"), the focal length, the aperture, the focus distance, the size of the print, the viewing distance and the quality of your eyes. Use this calculator to calculate the aperture where diffraction begins to dominate.

diffractie

The smaller the sensor, the less you can / have stop down before diffraction occurs and the image becomes less sharp ("softer"). With many compact cameras, you cannot stop further than 5.6 or 8 for this reason, while with SLR cameras with a full-frame sensor, the optimum sharpness ("sweet spot") is actually reached at these apertures. SLR lenses can often be set to aperture 22, but if you do not want to lose too much sharpness, you better remain under aperture 11 with an SLR camera with full-frame sensor.

Hyperfocal distance

The hyperfocal distance is the smallest distance at which a lens can be set, so that subjects at infinity are still sharp. It is the focus distance with the greatest depth of field. Calculate the hyperfocal distance yourself based on the desired print size, viewing distance and sensor size ("camera type").

Hyperfocaal

Hyperfocal distance in practice

If I want to use a 16 mm lens (converted to full-frame) to take a night shot that is sharp from front to - say one meter – back, choose:

  • a full-frame caera with a 16 mm lens on aperture 11
  • a camera with aps-C sensor and a 10 mm on aperture 5.6
  • a micro-43 camera with an 8 mm lens on aperture 4.5


These 3 different combinations will give the same result.

nacht

Focal length 

At Cambridge in Colour you can find a module to calculate the focal length you will need for capturing a subject, such as a kingfisher, full screen, based on the size of the subject, the sensor size ("camera type") and the distance to the subject.

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Magnification in practice at macrophotography

If you want to take a macro recording with a 50 mm lens with a magnification of 1 (the image on the sensor is as large as in reality), you need to choose a distance of 20 cm regardless of the type of camera (or sensor size).

macro

Macrophotography: Magnification

Do you want to calculate what magnification you can achieve with macro photography? The magnification only depends on the distance to the subject and the focal length of the lens.

magnification

Macrophotography: Depth of field

Depth of field is an essential parameter for successful recordings with macro-recordings. Use this calculator for calculating the depth of field of your macro recordings.

Macrp-DOF

Macrophotography: Diffraction limit calculator

At some point, further diaphragming is of no more use, because the increase in depth of field is offset by diffraction. With the Macro diffraction limit calculator you know when this is the case.

 macro-diffractie

Panorama photography: Field of View (FOV) calculation

The calcaulation of the Field of View is a handy tool for panaoram photography: how many shots do I need take with a particular lens to make a 360 degree panorama? Here is a link to a Dutch website where you can find an angle calculator at the bottom of the page.

Beeldhoek

 

Similar photographic calculations:

 

Comments  

+1 # RE: How to calculate depth of field, hyperfocal distanceWilliam Wilgus 2012-06-19 23:58
Crop Factor has nothing to do with Depth-of-Field.
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+1 # RE: How to calculate depth of field, hyperfocal distanceIvo 2012-06-20 20:33
Hi William,

I am not sure what you mean.
See the Depth of Field Equivalents calculator at: http://www.cambridgeincolour.com/tutorials/digital-camera-sensor-size.htm

regards

Ivo
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0 # Crops factor / Smaller Sensor impactNaveed Akhtar 2014-01-10 14:17
This is one of the most confused topic, I found across the photography community and for a valid reason, I will come to it later :)

Crop factor is probably not the best term as we normally use it for a full-frame lens mounted on an APSC sensor, since the image circle of the lens remain same, but cropped in the middle. I would say the the "Smaller sensor" have an indirect impact on Dof (Depth of field). Now, if you see the Dof calculating formula (Google it, if you like) has no variable for the size of sensor.

However, the focal length is inversely proportional to it. That means at longer (higher) focal length, shallower (less) is the Dof. There are two other parameters (f stop and magnification) but the point to notice is, the sensor size determines how much focal length you need to give you an "angle of view".

So larger the sensor size is, longer focal length you need to produce an image circle that is big enough to cover the sensor size!

That's why you notice shallower Dof on 50mm f/1.8 lens on full frame camera body then a 50mm (Fullframe Equivalent) f/1.8 lens on 4/3. Because 50mm (Equivalent) coverage on 4/3 camera can be achieved by an image circle with a lens of 25mm (Physical) focal length. Which is less than 50mm, so Dof is deeper.

When a lens designer / engineer see the mathematical equation he would bluntly state, "Sensor size has no impact on Dof", while an experienced photographer will swear on his life that "it does".

My 2c
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