A Site for Photographers by Photographers

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

Featured Equipment Deals

How to Get the Most Out of a Photography Workshop Read More

How to Get the Most Out of a Photography Workshop

Attending a photography workshop can be a great way to take your images to the next level, but it can also be a big investment in time, money, and travel. By following these 7 simple tips, you can...

Latest Equipment Articles

Nikon D750 Review Read More

Nikon D750 Review

Nikon introduced the D750, the first full-frame DSLR to feature a tilting LCD and built-in Wi-Fi, in September 2014. In this in-depth review Shun Cheung discusses the ins and outs of this new offering...

Latest Learning Articles

Faces of Photo.net Slideshow Read More

Faces of Photo.net Slideshow

This selection of 25 faces is from the distinct collection of portraits on photo.net by our member photographers.


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