The February/March 1969 issue of Camera 35 magazine indicates that best resolution was achieved f/11 and praised the lens for having high contrast. The review also notes the similarity to the Soligor T-4 lenses. It is believed the both the Vivitar and Soligor T-4 lenses were designed by Tokina with slight customizations made to the specifications of each company.
Badging: ... Vivitar
Manufacturer: ... Tokina
Manufacture Date: ... ca 1969
Focal Length: ... 105mm
Aperture Range: ... f/2.8 - f/22
Diaphragm Type: ... Automatic
Diaphragm Blades: ... 8
Filter Diameter: .... 49mm
Minimum Focus: ... 1.5m (5 feet)
Mounts: ... T-4 (adapters for Canon FL, Exakta, M42, Nikon, Minolta SRT, Miranda Sensorex)
Elements: ... 4
Groups: ... 4
Weight: (unknown)
Accessories: ... built-in retractable lens hood
Example Serial Numbers: ... 379001097
Image of Camera 35 Magazine Page:
https://www.flickr.com/photos/nesster/5262734069/sizes/o/in/photostream/
Reviews for the Soligor version of this T4 lens are found here:
https://www.pentaxforums.com/userreviews/soligor-105mm-f28-tele-auto.html