I have a Canon EF 28-105mm F3.5-4.5 USM. Its a strange model and I have only ever seen perhaps one reference on the internet alluding to the possible existence of a fourth version – a variation on the flower-macro symbol version (mkI.)
My Canon EF 28-105mm F3.5-4.5 USM – the missing version? MkIa perhaps?
They do exist, however they must be very rare. Mine is one of these. Let me explain by way of describing the different versions first.
The Canon EF 28-105mm F3.5-4.5 USM is generally accepted to have three versions as described on Wikipedia or this more detailed page at EBay.
The first version, manufactured from 1992 onwards, has five aperture blades. Despite the generally applauded optical quality of this older Canon EF lens, the five blades make for somewhat a poor type of bokeh. The lens is identified by a flower symbol – Canon’s earlier designation for lenses with macro capability, shown thus:
From 1999 a newer version, utilising the same body/optical mechanics, adopted seven aperture blades instead of five. Technically this was a Mark II lens, denoted by the now customary word, ‘MACRO’ instead of the flower symbol:
This version was made in Japan as was the earlier one. Both this and the earlier five blade model had ‘Japan’ inscribed on the bevel edge of the lens.
A slightly different version of the MkII came out in 2003. Still the same seven blade design but was manufactured in Taiwan. This Taiwanese version does not denote an origin of manufacture as shown below. The only place its origin of manufacture can be seen is etched beside the lens mount.
Later on (2007) the Taiwan version was issued with all lettering/symbols entirely in white instead of yellow (for MACRO) and the iconic Canon gold band!
This final (sort of MkIIIa) version of the 28-105 USM ceased in 2010 when the more modern version, the Canon EF 28-105mm 1:4-5.6 Ultrasonic came on stream. This 1:4-5.6 lens according to many sources produces a dreadful quality of image so we will not divulge further.
Back to the original 28-105! It is recognised that the 28-105 USM’s modification from five aperture blades to seven was mirrored by a change also from the flower symbol to MACRO. Prior to this however a short-lived Mk1a version was produced. This had the flower symbol and SEVEN aperture blades.
Either it arose because Canon began adding the seven blades at the very end of the original production line – or made a decision once the MkII production line had begun – upon a change of symbol to clearer denote the lens’ macro capability.
The 7 aperture blades in my 28-105mm F3.5-4.5 USM with flower symbol: