Aperture ...

the_monkey

http://www.flickr.com/photos/whitehouse/5167381996/



I see this is shot at 35mm f/2.2


What is the point in using such a wide aperture when not focusing
on a particular object ? seems a narrow ap. would be better to get
more of the action in focus yeah ?

Apart from low light conditions I can't see the advantage.

bogmanfan

Freezes the action i would imagine. There is movement in the scene, so the wide aperture allows the fastest possible shutter speed.

gerk86

low light conditions are precisely why you open your aperture

5uspect

Also DoF widens with distance so as you approach infinity so does DoF. You'll notice that in the image the entire scene is in focus.

Ghost Train

more light through the lens, shorter shutter speed to freeze moving subjects.

also more light allow use of lower iso so less noise

the_monkey

5uspect wrote: »

Also DoF widens with distance so as you approach infinity so does DoF. You'll notice that in the image the entire scene is in focus.

So then how come it's a bad idea to use wide ap. for landscapes ?

5uspect

Because the lens has a sharpness sweet spot at a certain f-number. The glass alone isn't always enough to give a sharp image (small circle of confusion). So while the distribution of sharpness is a function of distance and f-number the peak sharpness of that distribution also depends on the particular optics and aperture.

It is also a bad idea to shoot with too small an aperture as you can get diffraction effects at the extreme end.

5uspect

5uspect wrote: »

Also DoF widens with distance so as you approach infinity so does DoF. You'll notice that in the image the entire scene is in focus.

Is there anything more detailed out there with regards to what you just posted?

I know that your depth of field changes with the distance you are from a subject, but I don't really know much about it at all. Would love to read up on it properly.

5uspect

This article is excellent:
http://toothwalker.org/optics/dof.html

as is his DoF calculator:
http://toothwalker.org/optics/vwdof.html

Cambridge in Colour is also an excellent resource.
http://www.cambridgeincolour.com/tutorials.htm

Gonna head to bed soon, but will take a look tomorrow. Cheers 5uspect.

charybdis

the_monkey wrote: »

So then how come it's a bad idea to use wide ap. for landscapes ?

It's not, at least it's not necessarily. The "rules" of landscape photography (or any other kind of photography) aren't as ironclad as some would have you believe. The reality is that you should make decisions appropriate to the image you want to achieve. Often times, in landscape photography, it is possible to use low ISO ratings and slow shutter speeds with a small aperture because the subject is relatively static and the camera is on a tripod. Depending on the focal length and focus distance used, this typically results in an image with a deep depth-of-field and pleasing tonal characteristics, which is usually preferable in traditional landscape photography. However, any of these things may or may not be desirable to you; you have to make decisions about how you want to get your desired image.

Thecageyone

Most Landscapes are rarely in similar poor lighting conditions as indoor shots. There will always be light to play with, and as mentioned using a tripod allows slower shutter speeds [or VR, as you're shooting a static scene] Landscapes are much, much further into the distance too. Narrower apertures help ensure more sharp, in focus area. The shot here is indoors, up close enough to the subjects to allow the wide aperture, more chance of most of the scene in focus. Photographer might have got a little lucky, I bet he ripped off more than few shots to get this one.