A Site for Photographers by Photographers

Community > Forums > photo.net > Lenses > Promaster 100-400 4.5-6.7 w/...

Featured Equipment Deals

Latest Equipment Articles

The Week in Photography News Read More

The Week in Photography News

February 21-27, 2015: Hear the latest goings-on in the photography world, from product releases to event and campaign announcements and more.

Latest Learning Articles

Teaching with the Nikon School: An Interview with Photographer and Instructor Reed Hoffman Read More

Teaching with the Nikon School: An Interview with Photographer and Instructor Reed Hoffman

An instructor with the Nikon School since 2002, Reed Hoffman speaks with photo.net about his love for both photography and teaching, and what makes the Nikon School a valuable resource for...


Promaster 100-400 4.5-6.7 w/ Elan IIe

Tim Robison , Aug 20, 1999; 08:56 p.m.

I recently purchased a used Promaster 100-400 4.5-6.7 lens used at a great price. When on the Elan IIe, at 400 the aperture reading is 5.6. My question is, is the lens actually at 6.7 when I get the 5.6 reading, or should I manually select the 6.7 aperture? This lens is the same as the Vivitar 100-400 and the Phoenix, anybody with experience with this lens would be appreciated if they would share their knowledge...

T. Robison

Responses

Jim Strutz , Aug 20, 1999; 10:57 p.m.

Tim,

This is fairly common with small aperture zooms. They report f:5.6 because most Canon EOS cameras (and others as well) are designed to NOT allow auto focus with smaller apertures. Canon builds them to reliably AF down to f:5.6 and doesn't want people to complain about erratic performance with slower lenses.

In actual practice most EOS bodies will AF as low as f:8, but only if there is sufficient light and contrast. I wouldn't worry about it. AF performance will not be the greatest but the exposure will still be accurate even with the wrong f:stop being reported.

Back to top

Notify me of Responses