Go Back   Steve's Digicams Forums >

LinkBack Thread Tools Search this Thread
Old May 19, 2005, 5:09 PM   #1
thommas's Avatar
Join Date: Jul 2004
Posts: 43

I am buying either Sigma 18-200 DC or Tamron !8-200 Di XR. Both 3,5-6,3 Which one is better zoom lense? Can anyone send links with pictures taken with both these lenses?

f1.4 is twice as fast as f1.8. how about 2.8 and the "next level" which is 3.5? is 2.8 twice as fast as 3.5 as well? and 3.5 and 4, 4 and 6.3....so on?
thommas is offline   Reply With Quote
Sponsored Links
Old May 20, 2005, 5:38 AM   #2
Nagasaki's Avatar
Join Date: Jan 2004
Posts: 897

Full F stops are F2 F2.8 F4 F5.6 F8 F11 F16 F22 F32 each time you increase the F number you half the amount of light. F number between those listed are usually half stops so change the amount of light by a quarter.
Nagasaki is offline   Reply With Quote
Old May 20, 2005, 6:42 PM   #3
Senior Member
NHL's Avatar
Join Date: Jun 2002
Location: 39.18776, -77.311353333333
Posts: 11,599

f/6.3 is only a 1/3 stop from f/5.6... :idea:

On some cameras (default to 1/2-stop), the f/6.3 will be rounded down and register as f/5.6 in the viewfinder and EXIF - unless one programs the camera to increment in 1/3 stop!
NHL is offline   Reply With Quote

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 On
Pingbacks are On
Refbacks are On

All times are GMT -5. The time now is 3:29 PM.