Problems with Canon EF 50mm f/1.8 Lens

The bizarre, off topic and biased comments notwithstanding, DOF is
related to focal length, film/digital format, subject distance, and apeture.
It is largely unrelated to manufacturer. You could do a google search for
online free calculators that will give you DOF after you put in the details
of your lens. For example,

http://dfleming.ameranet.com/dofjs.html

DOF is not an exact number, it relates also to human tolerance of focus
variance. Mathematically this is repersented as a 'circle of confusion'
correction factor.

Dave

"J?rg Preddimann" wrote in message
om...
The Last Gunslinger wrote in message
...
Hi All
I bought a Canon EF 50mm f/1.8 lens a couple of months ago.
The 'in focus' depth (dont know what this is called) appears to be about
1 or 2 cm at f/1.8 at a distance of 1-2 metres.
Is this about right?
Is there any calculation to work out the 'in focus' depth?
Is there a technical term for the 'in focus' depth?

The lens is attached to a 300D.

Cheers

This is a frequent occurance with Canon autofocus lenses. The problem
is poor quality control and very bad sample variation. Canon
outsources the manufacturing of its non L lenses (and the 300D CMOS)
to sweat shops in the poorest sections of Asia. The exploitation of
slave labor by Canon is the reason why you can buy this lense for $60
USD. Switch to Sigma to avid this problem. Sigma makes lenses for your
300D, but you would be better of going native and buying the much
better Sigma SD10 body too. You will gain:

1--a professional body with excellent lenses, & better image quality
than anything Canon
2--a self-cleaning Foveon sensor with 3 colour layers like film
(instead of the grayscale, poorer version of the already poor 10D CMOS
outsourced to sweat shops in Asia for manufacturing by slave labor)
3--built in camera shake stoppage so you will almost never need a
tripod.


--

Jörg Preddimann

On Tue, 13 Jul 2004 03:16:07 +1000, " Miro" wrote:



DOF is not an exact number, it relates also to human tolerance of
focus
variance. Mathematically this is repersented as a 'circle of confusion'
correction factor.

The threshold at which an image is seen as in-focus is a precise number.

Yeah??

The
final judge is perceptual acuity not mathematical probability. At any given
range an image is sharp for a given set of conditions.

There is no need to limit the tolerance to infinite precision if the goal is
attained.


And in English ... ?