Originally posted by Pepe Guitarra Can anyone tell us if there is any difference in the optics or any other aspect of the two Tamron 105mm f2.5 lens versions: Adapt-a-matic vs. the Adaptall?
I have the Adaptall 105/2.5 (CT-105) but I have yet to see an Adaptamatic 105/2.5 (JOG-25AU). According to adaptall-2.org, they are both 4 element, 4 group lens, same max aperture opening but JOG-25AU has shorter minimum focus. They both have an A/M slide switch, I can confirm the CT-105 with a PK/A Adaptall-2 adapter will let you shoot in A mode on my Pentax DSLRs but I am doubtful if an Adaptamatic lens will do the same. I would say they share the same optical formula (difference might be the lens coating or lack of?)