Go Back   Steve's Digicams Forums > Digital SLR and Interchangeable Lens Cameras > Nikon Lenses

Thread Tools Search this Thread
Old Feb 12, 2010, 3:10 AM   #1
Join Date: Dec 2009
Location: Los Angeles, California, USA
Posts: 87
Default Calculate fstop at any given focal length?

I have a 85-300mm SUN zoom lens (circa 1982), without any markings for aperture range. (Such as f/5-7.2 or whatever)

The widest f/stop is 5, so how do I calculate f/stop at ___mm focal length?

Or is it one of those fixed f-stop lenses that remain at the same f/number at any focal length?

NothingRare is offline   Reply With Quote
Sponsored Links
Old Feb 12, 2010, 4:28 AM   #2
Super Moderator
Mark1616's Avatar
Join Date: Oct 2005
Posts: 7,396

As you go from the 85mm setting to 300mm the widest aperture will change from f5 to 7.2 at certain points. I'm not familiar with the lens so have no idea at what points it changes. Putting it on a camera should show where the aperture is going from f5 to 5.6 to 6.3 etc.
Mark1616 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 Off
Pingbacks are Off
Refbacks are Off

All times are GMT -5. The time now is 6:45 PM.