How come telephoto part of a zoom lens has shallower DOF?

[wizz747]

Not practical to do an indepth technical explanation here. Suggest you look up this link
http://en.wikipedia.org/wiki/Depth_of_field
Fred

Alright matey, thank you.

 

[Diavonex]

Depth Of Field is affected by:

1. Aperture

2. Subject distance

3. Focal length

4. Sensor format

 

[android17]

Bigger F number = deeper DOF?

Smaller F number = shallower DOF?

sorry...bigger number = shallower DOF.

:sweat:

 

[ZerocoolAstra]

errrr... because DOF is also a function of focal length?

Actually in the instance if the apertures were the same, a telephoto lens will have the same dof as a wide lens.

http://www.clubsnap.com/forums/newreply.php?do=newreply&p=6578893

http://www.cambridgeincolour.com/tutorials/depth-of-field.htm

Ryan

ahhh thanks for the correction.
Yes it didn't occur to me that I'm technically incorrect.
It's because when using telephoto lenses, the subject tends to occupy more of the frame, hence affecting other parameters which in turn affect DOF.

 

[chiangkxv]

[youtubehd]OUYuUs1aaCU[/youtubehd]

watch this for explanation and illustration. ;p