How do you select your aperture in your photos?

EtherArts wrote: Hello! Congrats on the Sony A7r. It's a pro-level camera. Aperture choice in Aperture Priority or Manual mode affects depth of field and light. Wide apertures (e.g., f/1. blur backgrounds, ideal for portraits. Smaller apertures (e.g., f/ keep more in focus, great for landscapes. Experiment based on creative goals and lighting conditions.

   best advice  "Experiment"  

Ozzie_Traveller wrote: G'day Storz

The aperture settings in the camera are used for three main things ..... a) exposure control in conjunction with the best shutter speed, -or- b) to create / determine the Depth-of-Field that you want for the scene, and/or c) to determing the level of image sharpness from the centre to the corners of the photo

Looking at these in reverse ... sharpness - if you use a magnifying glass to look at a subject, you will quickly see that the edges of the image are blurry when compared with the middle. Camera lenses are much better, but as we are a fussy lot !! we want good edge sharpness as much as possible. So comes the recommendation to use a mid-range aperture for good image quality, and to be aware that when using the lens at wide-open (small aperture numbers) then the IQ may not be perfect

Secondly- when you have a subject that needs more or less Depth-of-Field, then you can run the apertures down to F16, F22 if needed, or out to F4 maybe if you do not need DoF

Finally, it is alwayas a balancing act (like a child's see-saw) to balance the Aperture to the best Shutter speed so that the exposure is correct and the end result is what you wanted

Remember also that the aperture number is the bottom of a fraction ... the diameter of the aperture hole is a fraction of the millimetres of the lens focal length. So small numbers F2, F4 etc are 1/2 - 1/4 of the focal length and large numbers F16, F22 are 1/16 or 1/22 of the focal length

Hope this helps
Phil from the great land Downunder
www.flickr.com/photos/ozzie_traveller/sets/

Thanks for this overview, Ozzie, especially the aperture fraction (i.e. F2 as 1/2 of the lens focal length).  That is a very helpful way of describing it.