Go Back   Steve's Digicams Forums > Digital Cameras (Point and Shoot) > Panasonic / Leica

Reply
 
Thread Tools Search this Thread
Old May 26, 2005, 2:25 PM   #1
Junior Member
 
Henrik L's Avatar
 
Join Date: Apr 2005
Posts: 27
Default

What is the focus range at 12x zoom with a nikon 4T close-up lens or equivalent 3+ diopter?
Henrik L is offline   Reply With Quote
Sponsored Links
Old May 26, 2005, 3:31 PM   #2
Senior Member
 
fmoore's Avatar
 
Join Date: Sep 2003
Posts: 2,116
Default

Henrik L wrote:
Quote:
What is the focus range at 12x zoom with a nikon 4T close-up lens or equivalent 3+ diopter?
Henrik - The formula is F=1/d where F is the focus (or working) distance in meters and d is the diopter power of the lens. A +1 dipoter lens would focus at 1 meter or about 39". A +3 diopter lens such as the 4t would focus at 1/3 meter or about 13". Since at lower zooms the depth of field is greater, there is a range of distances where you will obtain focus. For instance, at 6x zoom you might focus from 12-14" from the subject because the subject could be in focus at either the front end or the back end of the dof. At 12x zoom the dof is very small; maybe 5mm deep. Consequently, a little bit of movement closer or further will bring the subject in or out of focus. That is the trick to macro shots; setting the zoom where you want it for framing and then moving the camera physically closer or away to obtain optimum focus. It takes practice along with good light and a still subject. And patience.

Fred

fmoore is offline   Reply With Quote
Old May 29, 2005, 4:34 AM   #3
Junior Member
 
Henrik L's Avatar
 
Join Date: Apr 2005
Posts: 27
Default

Now I understand, thank you!
Henrik L 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 7:08 AM.