Lumix FZ40 depth of Field
may i ask you about DOF for an FZ40 ... it's driving me nutty trying to blur the background behind the main focused item ...
whether i shoot from close or ,say ,1 or 2 metres away ... background remains unblurrred whether it's on IA, or Av with f2.8 ( lowest i can go
) ... also , if i set it at f8 , remains unblurred and looks same as the f2.8 ...
i have searched the Net , got some info ,and read a number of magazines,which really just say to set a low f number ... was some comment about
"maxing the telephoto " , but i don't understand that ...
maybe it's just the LEICA 25-600 wide angle lens ?
whether i shoot from close or ,say ,1 or 2 metres away ... background remains unblurrred whether it's on IA, or Av with f2.8 ( lowest i can go
) ... also , if i set it at f8 , remains unblurred and looks same as the f2.8 ...
i have searched the Net , got some info ,and read a number of magazines,which really just say to set a low f number ... was some comment about
"maxing the telephoto " , but i don't understand that ...
maybe it's just the LEICA 25-600 wide angle lens ?
it'll be down to the small sensor that's used in your camera unfortunately. moving to a smaller aperture
(f/8 or f/11 for example) will only increase the depth of field, not reduce it.
to get shallow DoF, you ideally need a larger sensor (M4/3, APS-C or Full Frame) and a large aperture.
you "can" isolate your subject to some extent by using the telephoto at a longer focal length and placing
your subject sufficiently far enough away from the background to give the impression of blur. a downside
to this will be the image looking "soft" and less sharp than at a shorter focal length.
if your camera has a filter thread, you could invest in a cheap set of "close up" lenses (normally a tenner
for 4 on ebay), but these will restrict you to smallish objects like coins or insects, but will significantly reduce
your depth of field.
it's trial and error i'm afraid.
hopefully someone with a better understanding may come along and explain a little better.
hth
Ste
(f/8 or f/11 for example) will only increase the depth of field, not reduce it.
to get shallow DoF, you ideally need a larger sensor (M4/3, APS-C or Full Frame) and a large aperture.
you "can" isolate your subject to some extent by using the telephoto at a longer focal length and placing
your subject sufficiently far enough away from the background to give the impression of blur. a downside
to this will be the image looking "soft" and less sharp than at a shorter focal length.
if your camera has a filter thread, you could invest in a cheap set of "close up" lenses (normally a tenner
for 4 on ebay), but these will restrict you to smallish objects like coins or insects, but will significantly reduce
your depth of field.
it's trial and error i'm afraid.
hopefully someone with a better understanding may come along and explain a little better.
hth
Ste
many thanks ,guys 
understand about aperture size ... when i mentioned f number i meant the f2.8 etc.. not the opening size ... and that's what i couldn't understand ,ie the f2.8 and f8.0 both being unblurred , even tho the f2.8 opening is larger than the f8.0 ...
so it's the basic limitations of the camera , guess i'll create the blur in Photoshop ...
thanks for your help ...
understand about aperture size ... when i mentioned f number i meant the f2.8 etc.. not the opening size ... and that's what i couldn't understand ,ie the f2.8 and f8.0 both being unblurred , even tho the f2.8 opening is larger than the f8.0 ...
so it's the basic limitations of the camera , guess i'll create the blur in Photoshop ...
thanks for your help ...
Putting it in simplistic terms the DOF is dependent on the aperture of the lens, the focal length of the lens and how close you are to the subject. The bigger the aperture (or the lower the f number) the shallower the DOF will be. The longer the focal length the shallower the focal length will be. The closer you are the shallower the DOF will be (as you'll notice when you try macro shots).
The reason that small sensor cameras have a large DOF is because the smaller sensor dictates the use of a smaller focal length lens for a given angle of view - it's more complicated than that but this is a reasonable way of looking at it. So the FZ40 uses a 7mm lens (roughly) to achieve the same angle of view that a 35mm FF camera would have with a 35mm lens - what's called a "crop factor" of 5.
Have a look at an online DOF calculator and it'll show you roughly how it works. To get the minimum DOF from your camera you need to select the longest zoom, the widest aperture and the closest distance to the subject. The problem you'll immediately find is that the longer the zoom the shorter is your minimum focus distance - and also the maximum aperture goes down too. So it's a matter of trial and error to see what works best.
The reason that small sensor cameras have a large DOF is because the smaller sensor dictates the use of a smaller focal length lens for a given angle of view - it's more complicated than that but this is a reasonable way of looking at it. So the FZ40 uses a 7mm lens (roughly) to achieve the same angle of view that a 35mm FF camera would have with a 35mm lens - what's called a "crop factor" of 5.
Have a look at an online DOF calculator and it'll show you roughly how it works. To get the minimum DOF from your camera you need to select the longest zoom, the widest aperture and the closest distance to the subject. The problem you'll immediately find is that the longer the zoom the shorter is your minimum focus distance - and also the maximum aperture goes down too. So it's a matter of trial and error to see what works best.
thanks ,Steppenwolf .... i think i get it.... i clearly understand the result of a lower / higher f number , but , if i select the longest zoom by moving the zoom lever , then everything in the LCD goes out of focus and all i see is a colored blur ?
thanks for your advice
thanks for your advice
