# F/2.8 Depth of Field



## LuckySo-n-So (Apr 24, 2009)

Everything I've learned so far tells me that a photo taken at f/2.8 gives a very shallow depth of field.

I saw this photo a couple of days ago and checked the EXIF data, which showed that it was taken with a *Canon 50d, f/2.8, 1/640th, ISO 3200, 148mm focal length*( I'm assuming a 70-200 2.8 IS L lens). The photo is copyrighted, so here is the link:

http://farm4.static.flickr.com/3538/3469203556_e349e4c0c0_o.jpg


What makes the depth of field so deep at this aperture? High ISO I'm guessing?

BTW:  I don't know if this guy is a pro or not, but he does capture some pretty good major college sports photos.  His *flickr *ID is *lsuconnman*


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## Steph (Apr 24, 2009)

LuckySo-n-So said:


> What makes the depth of field so deep at this aperture? High ISO I'm guessing?



No. Camera to subject distance. The farther the subject, the deeper the DOF.


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## LuckySo-n-So (Apr 24, 2009)

Steph said:


> No. Camera to subject distance. The farther the subject, the deeper the DOF.


 
D'oh!! makes sense. :banghead:

eta: do you sometimes feel like "even though even though you are playing with a full deck," someone replaces the Ace of Spades with an extra Joker just to F*** with you?


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## Overread (Apr 24, 2009)

ISO won't affect the depth of field - it mostly only affects the shutter speed and noise levels in a shot. 

Distance though is probably playing a key part in this shot - a shot taken at f2.8 in macro world will have a depth of field only milimeters wide - portrate distance a few cms - move to telephoto distances and it increases still. I think there are some depth of field calculators online that you can use to get an idea of what is the actual depth of field at different distances - I suspect also that focal length might be a contributing factor also


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## Phranquey (Apr 24, 2009)

Steph said:


> No. Camera to subject distance. The farther the subject, the deeper the DOF.


 

Yup. The farther away the subject, the closer you get to the infinity focus, which will get you a much greater DOF.


EDIT:   BLESS IT, Overread!!!! I have now lost count how many times you jumped me on an answer.


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## Chris of Arabia (Apr 24, 2009)

This is a useful tool that you play with to explore the effects of DoF at a given distance - Depth of Field Calculator


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## Overread (Apr 24, 2009)

Phranquey said:


> EDIT:   BLESS IT, Overread!!!! I have now lost count how many times you jumped me on an answer.




but Steph beat us both this time round


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## Garbz (Apr 25, 2009)

Aperture. Camera to subject, and subject to background create depth of field. Given a same aperture, and same sized subject, the longer the lens, the further the camera to subject distance becomes. Have a look at these all shot at f/2.8:

28mm






50mm





200mm


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## djacobox372 (Apr 30, 2009)

I'm "guessing" that a teleconverter was used on that shot as well, which turns it into an f4 lens.


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## RyanLilly (Apr 30, 2009)

djacobox372 said:


> I'm "guessing" that a teleconverter was used on that shot as well, which turns it into an f4 lens.



Wouldn't a teleconverter show up in the Exif Data; maybe not specifically as "1.4 teleconverter" etc, but at least actual focal lenght of combined lens and converter? In any case with a canon branded converter it would still register as F/4, i beleive.


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## Seefutlung (Apr 30, 2009)

Actually, ISO does not affect either shutter speed or aperture ... in generally terms, (none technical), adjusting one's ISO makes the sensor either more sensitive or less sensitive to light (more sensitive = less light is required for a "proper" exposure ... less sensitive = more light is required for a proper exposure).

Typically one can adjust either the shutter speed or the aperture to accomodate changes in ISO.

Gary


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## Garbz (Apr 30, 2009)

RyanLilly said:


> Wouldn't a teleconverter show up in the Exif Data; maybe not specifically as "1.4 teleconverter" etc, but at least actual focal lenght of combined lens and converter? In any case with a canon branded converter it would still register as F/4, i beleive.



The Canon and Nikon ones do, the aftermarket ones don't.


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## JerryPH (May 1, 2009)

LuckySo-n-So said:


> Everything I've learned so far tells me that a photo taken at f/2.8 gives a very shallow depth of field.



DOF is not determined just by apertre alone, but by a combination of the following factors:

1 - Aperture
2 - Focal length used
3 - Distance from camera to subject
4 - Distance from camera to background
5 - Distance from subject to background


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