# How to calculate depth of field at different resolutions

I have a DSLR (EOS 60D) and I use hyperfocal pro when setting up astro-photography. At lower resolutions though, such as in video mode, how can I calculate the depth of field?

The field of view barely changes so there is not much crop, but there is no continuous auto-focus so I want to keep the subject in focus.

Is the DOF the same as in photography modes, assuming the same aperture and focal distance?

And if it isn't, is there a similar app or calculator for the lower resolutions?

• You can check here: dofmaster.com/dofjs.html Apr 5, 2021 at 18:01
• Depth of field in astro-photography? Are you not focusing at infinity? "At lower resolutions though, such as in video mode" Lower resolutions? Video stack may be a better place to ask video questions. Apr 5, 2021 at 19:56
• There's no real calculation to be done regarding depth-of-field with astro work. The actual focus distance is about all that will be acceptable. Your ability to accurately focus is usually a wider variation than the total acceptable DoF. We hold point sources of light, such as stars, to a higher standard than most things that are acceptably sharp at infinity when the rear edge of the DOF is at infinity. I've shot frames containing both the moon and Jupiter. Both are much nearer than typical astro objects. If the Moon is optimally focused, Jupiter is not, and vice versa. Apr 6, 2021 at 12:44
• When I do astrophotography it may include the landscape, focussing the lens to what is marked as infinity leaves too much of the foreground out of focus, focussing to the hyperfocal distance is preferable for me and that varies based on aperture size. Apr 6, 2021 at 14:46

## 1 Answer

Depth of field does not vary by resolution; assuming you meet the minimum requirement (~ 1MP).

Depth of field does vary by sensor size though; because a smaller sensor will require more magnification/enlargement, which makes a lack of sharpness more apparent.

Depth of field is the same for video as it is for still images. You can use any of many calculators available assuming the viewing conditions will be standard and no cropping will be applied. If the viewing conditions are not standard, or the images/footage will be cropped, then the default results of a DoF calculator will be wrong; you would need to use a different CoC limit suitable for the output/viewing conditions.

• So the 2MP video will have exactly the same depth of field then? My thoughts were that if there were fewer pixels the circle of confusion can be bigger because the pixels on the image sensor are bigger. Or am I mis-understanding how video mode works? What is the minimum requirement? Apr 6, 2021 at 14:49
• @MParks, the CoC can be larger for larger pixels. But the CoC standard for image sharpness/DoF does not change; it is based upon the format size. E.g. a 2MP image and a 12MP image from the same sized sensor will have the same perceptible DoF/acceptable sharpness when displayed/viewed the same; the 12MP will just have more in reserve you can't really see (based on the CoC standard). Apr 6, 2021 at 15:24
• If the video from your camera is 2MP because it is skipping rows of pixels (to enable higher FPS rolling readout of full sensor area) the result will be different than if it is due to the video being in a crop mode (less than full sensor area). But there is no change in pixel size/area either way. Apr 6, 2021 at 15:24