I have been trying work out this depth of feild recently and i am getting nowhere what i am trying to do is blur the background when taking certain pics. I am bringing the F. down as far as it will go as i am led to believe this is the way to go, but the back ground is still in focus or not as blurred as i would like. Does the distance between you, the subject and the background determine how blurred the background is or has it something to do with the lens i am using.
thanks

use a large apature f2 or your largest

what do you mean bringing the f number down you want large f stops not small ie not f16 etc

Have a read of this ... http://www.diglloyd.com/diglloyd/free/back...groundBlur.html

Hope it helps

Julia

Paul, when you think of apertures think in fractions i.e. 2 =2 parts of one, and 16 = 16 parts of 1. Therefor 1/2 is bigger than 1/16. Actually a LOT bigger:)

Den

The largest apature i can get at the moment is F4.4(if my memory serves me correctly) is this to small for creating background blurr or am i doing something else wrong.
Looking at thearticle julia posted they talk of apatures of F1.2 i cant get anywhere near that

f4.4 should be Ok, but try combining that aperture with zooming in on your subject, the combination of the two will help get the desired effect.

Regards

Cliff

** Just a quick edit, I took the following shot yesterday, nowt special, but it does show the effect on DOF when using the combination of a large aperture (F5.6) and zooming in with a telephoto lens (300mm (450mm/35mm equivalent)).



This post has been edited by rabster: Jan 20 2006, 08:03 PM

The one thing you haven't told us is the lenth of the lens you are using. If it's a standard or wide then even wide open you will struggle to throw the background but anything over 180mm and you will notice it going. If you get up to 300mm it will be much better

The lens i have been using is a standard 14-45mm mainly but i also have a 45-150mm.Is it not possible with these.

If photoing someone or something - I take into account what does the surroundings (background/foreground) bring, if anything to the photo to enhance it, or do I just want the subject to be isolated in the photo with the surroundings blurred (the bokeh).

For instance if I was photographing someone, I may just want them in focus ... so I would use a shallow depth of field, depending on the distance I am away from them (ie F2) ... so they are firmly in focus, nice and sharp and their surroundings are blurred.

Then I may be photoing someone whoms surroundings does bring something to the photo - ie, lately I was photoing a darts competition and I photographed the winner with the trophy, I would normally want the winner to be the main subject of the photo with no distracting surroundings in the shot ... BUT ... I wanted a dartboard in the background just to the side of him, so I wanted that just slightly OOF (out of focus), so anyone who sees picture in local newspaper can spot straight away what the person has won the trophy for, but yet the winning guy holding the trophy is nice and sharp. (hope that makes sense). (depending on distances between me, subject, and backgrounds ... around F4 to F6 usually ... or you have to take a few shots until you find setting you are happy with)

Landscape photography you usually want a fairly large depth of field to get as much i, so shooting at F11 upwards (I usually use F16) ... available light is a main factor here also.

Lenses with shorter focal lengths generally produce images with larger depth of fields (ie your wide angle lenses ... or wide end), where as lenses with larger focal lengths (70mm + ... your telephotos) produce images with shallower depth of fields ..... this all depends on situation and surroundings you are photographing, and distance.

As you can expect, coming closer to a subject will reduce depth of field (as you are physically closer), where as moving away from a subject will increase the depth of field - depending on what F stop you have chosen.

Here are two examples that I have at hand online ... (not the best of photos or examples I know - but I have them at hand online)



This Flower was taken at F4 (shallower depth of field)



This Landscape was taken at F16 to squeeze as much detail out of foreground and the background (an ND grad filter was on the camera also, to try and not to overexpose to much at F16 .... shot taken at midday ... thats why its generally said to be better to photo landscapes during last hour of light and first our of light if your not using filters so you have a litte bit of control over the exposure.

Anyway, hope my ramblings on and on have been of some interest to someone.

Gillies