There is something that bugs me about aperture...

I understood that aperture will influence my picture on both light and focus zone.

Now when taking a picture, I find it difficult to know precisely which aperture would fit best to give me a blurred background and focus on multiple close objects (Legos caracters for example)...

For example, I know that I'm using a lens with a XXX mm focal, I'm 1 meter away from my subjects and I want my focus area to be about 10 cms long (covering the distance between the caracter being the closest to me and the one being the farthest)... Is it possible to precisely calculate which aperture I need to select instead of painfully try and change all the possible value and check the result on my pictures...

Does it exist a rule of thumb to know that? It's even more important when trying to capture living things (insect on a large flower) and we need to take quickly the good picture...

Thanks for your precious advices...

  • \$\begingroup\$ I'm not sure the math really allows for a workable rule of thumb - but there are plenty of smartphone apps to do just that and most cameras have a depth of field preview button. \$\endgroup\$ Commented Jul 7, 2013 at 7:38
  • \$\begingroup\$ Have a look at this website. \$\endgroup\$
    – Pouya
    Commented Jul 7, 2013 at 8:44

1 Answer 1


What you are looking for is a way to quickly determine which aperture setting will allow the Depth of Field (DoF) you desire.

There are several ways to do this:

  • \$\begingroup\$ I downloaded an application on my phone and it's very helpful! I also thought about printing a table with dof informations about my lenses... Thank you very much for your answer! \$\endgroup\$
    – Andy M
    Commented Jul 8, 2013 at 19:50

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.