Go Back   Steve's Digicams Forums > Digicam Help > General Discussion

Reply
 
Thread Tools Search this Thread
Old Aug 24, 2007, 7:02 PM   #1
Senior Member
 
Join Date: Feb 2007
Posts: 129
Default

Been looking at getting an ultrawide angle lens, somewhere less then 20mm for landscapes and such but can't seem to find one with a D.O.F. scale. Asked the store help but he made it sound like it's a dying breed for dSLR. The reason I want the scale is for more percise hyperfocal finding, anybody have suggestions?
ahill876 is offline   Reply With Quote
Sponsored Links
Old Aug 24, 2007, 8:17 PM   #2
Senior Member
 
Bob Nichol's Avatar
 
Join Date: Apr 2003
Location: Eastern Ontario Canada
Posts: 822
Default

D.O.F. scales are hard to implement with the modern lenses such as those with internal motors as there is only a number in a window. It is even harder with zoom lenses not to mention Nikon "G" lenses with no aperture ring at all.

It would seem that they are an endangered species as you noted.
Bob Nichol is offline   Reply With Quote
Old Aug 25, 2007, 11:05 AM   #3
Super Moderator
 
peripatetic's Avatar
 
Join Date: Nov 2004
Posts: 3,599
Default

As Bob says, essentially impossible with a zoom.

Secondly with digital print sizes and web output varying so much it makes less sense to etch onto the lens.

Thirdly (as a corollary of the second point) the lenses are being attached to cameras with different sized sensors/film, which implies different enlargements, which means in effect that DOF field varies with sensor size.

Finally the processing options are so different with digital that extra sharening can often give the impression of greater DOF, and conversely high-resolution lenses and larger prints give shallower DOF. It's a bit of a mess really.

http://www.dofmaster.com can generate some tables for your particular set of variables.
peripatetic is offline   Reply With Quote
Old Aug 25, 2007, 2:30 PM   #4
NHL
Senior Member
 
NHL's Avatar
 
Join Date: Jun 2002
Location: 39.18776, -77.311353333333
Posts: 11,547
Default

ahill876 wrote:
Quote:
Been looking at getting an ultrawide angle lens, somewhere less then 20mm for landscapes and such but can't seem to find one with a D.O.F. scale. Asked the store help but he made it sound like it's a dying breed for dSLR. The reason I want the scale is for more percise hyperfocal finding, anybody have suggestions
Yeap - All the Sigma EX series wide angle lenses still have DOF scales:
http://sigmaphoto.com/lenses/lenses_...mp;navigator=4

-> Cheaper consumer grade lenses have done away with the "display window" - hence no markings (translate to lower cost)!



True zooms still have DOF scale as well - check out the 70-200 f/2.8 for example:
http://sigmaphoto.com/lenses/lenses_...mp;navigator=3

-> Problem is most modern zooms have gone varifocal relying on the camera AF to keep focus hence their focus distance changes as one zoom making the DOF scale inaccurate and impractical...

In the older days of varifocal push-pull zooms one would see different squiggly colored lines along the lens barrel to mark the different DOF as it relate to the distances, but this design have fall out of favor to internal zooming mechanism where the barrel now stayed fixed hence the distance has to varies which each focal lenght forcing the markings to vary instead (when the distance marking are fixed on the lens)!

NHL is offline   Reply With Quote
 
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

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 Off
Pingbacks are Off
Refbacks are Off



All times are GMT -5. The time now is 11:03 PM.