Flowers - Depth of Field or Focus?

[Gobae]

I shot both of these flowers at f/6.0 but only the left hand side petals are clear. Is this a depth of field issue or a depth of focus problem? Is there a way to tell the difference and how can I correct a depth of focus issue?


Exif for above
Make NIKON CORPORATION
Model NIKON D40X
Aperture Value f/6
Color Space Uncalibrated
Exposure Bias Value 0 EV
Exposure Program Aperture Priority
Flash No Flash
Focal Length 300 mm
ISO 400
Metering Mode Multi-Segment
Shutter Speed Value 1/400 sec
Date/Time Fri 03 Apr 2009 03:49:52 PM MDT


Make NIKON CORPORATION
Model NIKON D40X
Aperture Value f/6
Color Space sRGB
Exposure Bias Value 0 EV
Exposure Program Aperture Priority
Flash No Flash
Focal Length 300 mm
ISO 400
Metering Mode Multi-Segment
Shutter Speed Value 1/100 sec
Date/Time Fri 03 Apr 2009 03:52:31 PM MDT

[Alexander]

Hi. I'm certainly no expert, but it looks to me as if the camera is focusing slightly behind where you wanted it to. This, plus the combination of a narrow depth of field at this distance, caused the problem. For solutions, I would suggest trying: (1) focusing on the petal closest to you. The results will tell you if the focus is slightly off or if it was just a mistake. (2) Stopping down the lens to a smaller aperture and using flash and/or a tripod with a long exposure.

Hope this helps.

Gary

[mipo]

Hi,
As a rule of thumb.
The focus is generally 1/3 in front of focus point & 2/3 behind.
Also most probably in the lens guide you will find the DOF chart.

You only indicate the f #.
Missing the focal lenght of the lens & if it was in Macro mode.

I know that for a 105mm. in Macro, mean focus at less than 1 foot, the DOF is less than .12 inch. (1/8)

[Gobae]

Originally Posted by mipo

You only indicate the f #.
Missing the focal lenght of the lens & if it was in Macro mode

According to the Exif (posted under each pic) the focal length was 300mm. Yes, it was in macro mode.

But if I'm understanding both of replies correctly f/6 is still too open, and we're talking about DOF that is typically going to be fractions of an inch deep.

[mipo]

Any aperture you choose in Macro mode will have very shallow DOF
And normally the longer the lens, the shallower the DOF
On my 105mm lens at 1foot the DOF is.
F2.8 6/16' & at f32 5/16' There is 1/16 difference between Maximum & Minimum Aperture

[wulf]

What lens? I'm guessing you are using an Xmm-300mm lens at the extreme end of the range. The trouble is that these lenses are frequently on the soft side. If you are at f/6 you are also probably only just a step down from the widest possible aperture, which is another factor that frequently leads to softness.

I'm not seeing anything notably sharp in either of these images but, if my guesses are right, you can get crisper flower shots out of it. Here's one from my 70-300mm lens (at 122mm and f/7.1):



Wulf

ps. you might need to view my image at a larger size back on Flickr but it is sharp round the bottom although it also illustrates the narrow depth of field.

[subrataofkris]

Can you try the spot metering or manual focus. since the DOF in this case (300mm, Macro and F/6) is shallow, may be it will help.

[tjphoto]

Is it hand held ,if so try a tripod and turn up the iso, I'm thinking it's a bit slow? and back off a bit and zoom a little instead.auto or manual focus?

[aprillove20]

Well, focusing on the petal closest to you.