Velocity Reviews - Computer Hardware Reviews

Velocity Reviews > Newsgroups > Computing > Digital Photography > Re: Problems with Canon EF 50mm f/1.8 Lens

Reply
Thread Tools

Re: Problems with Canon EF 50mm f/1.8 Lens

 
 
J?rg Preddimann
Guest
Posts: n/a
 
      07-12-2004
The Last Gunslinger <(E-Mail Removed)> wrote in message news:<(E-Mail Removed)>...
> 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
 
Reply With Quote
 
 
 
 
Dave
Guest
Posts: n/a
 
      07-12-2004
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" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed) om...
> The Last Gunslinger <(E-Mail Removed)> wrote in message

news:<(E-Mail Removed)>...
> > 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



 
Reply With Quote
 
 
 
 
DJ
Guest
Posts: n/a
 
      07-12-2004
Predders, you are just full of ****.


 
Reply With Quote
 
Miro
Guest
Posts: n/a
 
      07-12-2004

>
> 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. 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.


 
Reply With Quote
 
Chris Down
Guest
Posts: n/a
 
      07-12-2004
DJ

What on earth do you have against ****?




"DJ" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> Predders, you are just full of ****.
>
>



 
Reply With Quote
 
DJ
Guest
Posts: n/a
 
      07-13-2004
On Tue, 13 Jul 2004 03:16:07 +1000, " Miro" <(E-Mail Removed)> 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 ... ?
 
Reply With Quote
 
DJ
Guest
Posts: n/a
 
      07-13-2004
On Mon, 12 Jul 2004 17:27:17 GMT, "Chris Down" <(E-Mail Removed)> wrote:

>DJ
>
>What on earth do you have against ****?


On reflection nothing, it makes things grow. Preddy's rantings OTOH simply
diminish the discussions.

>
>
>
>
>"DJ" <(E-Mail Removed)> wrote in message
>news:(E-Mail Removed).. .
>> Predders, you are just full of ****.
>>
>>

>


 
Reply With Quote
 
Miro
Guest
Posts: n/a
 
      07-13-2004

"DJ" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> On Tue, 13 Jul 2004 03:16:07 +1000, " Miro" <(E-Mail Removed)> 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 ... ?


What you see is what you get. You dont need an Excel spreadsheet to figure
that out.


 
Reply With Quote
 
DJ
Guest
Posts: n/a
 
      07-13-2004
On Tue, 13 Jul 2004 20:40:28 +1000, " Miro" <(E-Mail Removed)> wrote:

>
>"DJ" <(E-Mail Removed)> wrote in message
>news:(E-Mail Removed).. .
>> On Tue, 13 Jul 2004 03:16:07 +1000, " Miro" <(E-Mail Removed)> 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 ... ?

>
>What you see is what you get. You dont need an Excel spreadsheet to figure
>that out.
>


So you are saying "if it looks sharp it is sharp"?
 
Reply With Quote
 
 
 
Reply

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Another question - How to convert medium format lens to equivalencyof a 50mm normal lens (35mm camera) in APS-C digital cameras aniramca@gmail.com Digital Photography 13 05-31-2009 10:02 PM
New Lens Comparison: Nikon 50mm 1.4D vs. 50mm 1.4G M-M Digital Photography 14 03-22-2009 02:32 PM
Re: 50mm 1.4 vs 50mm 1.8 Bob Williams Digital Photography 1 01-13-2009 02:41 PM
28mm or 50mm Fixed focus lens for Canon dRebel Siddhartha Jain Digital Photography 15 11-09-2004 03:21 AM
A good Canon 50mm Lens for Cheap? Dane Brickman Digital Photography 4 06-20-2004 03:09 AM



Advertisments