Omega designed iconic chronographs, the most known one beeing the Omega Speedmaster Moonwatch. There are however several other chronographs that deserve the attentions of the watch enthousiast and the collectors. The Omega Speedmaster Mark 4.5 is one of Omega's most interesting chronographs because of the number of complications that are offers. This watch was produced between 1974 and 1986.

Let's start first with the case. The Omega Speedmaster Mark 4.5 176.0012 case adopts a tonneau shape similar too the Speedmaster Mark II. It is a bulcky watch. The case is 42 x 45 mm large and 15.5 mm thick. The watch however surprisingly sits well on small wrist (as small as 16cm). The case has a sunburst polish on top. Collecor should pay attention to this feature as overpolishing would tarnich this optical effect, which is part of the charm of this watch. The case sides are brushed and a slim polished edge is separating the brushed sides from the brushed top. There also overpolishing would be harmful to the watch design.

The Omega Mark II was powered by the 861 caliber. In contrast the Mark 4.5 is powered by a Lemania 5100 based Caliber 1045 movement. It is an Omega's self-winding chronograph movement and it is known for its robustness. Its construction is far from being elegant: no column-wheel and it even has plastic parts inside. This caliber however offers numerous of additional features in comparison with the iconic Omega 321 and 861 calibers. These features are visible in the dial, which is my favorite part of the watch. The dial has a 24 hour sub-dial indicator at the 12:00 position, a chronograph 12-hour sub-dial at the 6:00 position, and a second sub-dial indicator at the 9:00 position. The date and day windows are located at the 3:00 position.

The main dial centralised the hour and minute hands as well as the chronograph second hand. The Mark 4.5 chronograph minute hand is my favorite feature. First I like the jet-shape of this white hand. Second, I often use the chronograph function and I appreciate to read the chronograph time (minutes and seconds) on the central dial instead of a tiny sub-dial. A tachymetre scale also appears on the inner bezel. The production of Lemania 5100 caliber stopped in the early 2000s, but this caliber gained since a cult status.

The Mark 4.5, as the Mark II, has a mineral crystal . The tachymeter scale is printed on the inner side of the crystal. Despite being a Speedmaster Mark 4.5, the text "Seamaster" and the seahorse logo appear on the case back.

Different bracelets were available for this model. Here is the Omega 1162/1/172 Bracelet, with folding clasp.

I love this watch for its complications and I like to this watch because it does not look like an Speedmaster Moonwatch. I don't want to be misunderstood, I love the moonwatch too but for different reasons. I really enjoy to use a chronograph, where the chronograph-minute hand is located on the main dial. It is a bulky watch but it does not look so bulcky on the wrist, also small wrist. The 5100 caliber is renowned for its robustness, so this watch should aged well. In fact the main concern with this watch is to find one that is in good condiction. I mean, it is a great tool-watch, and as such it should take hits and get marks. Polishing is the worse enemy of this watch. It is destroy it sunburst top, the sharpness of the case. To find one with a minthy case, here is the challenge. It should be mentioned the Omega Speedmaster 376.0822 "Holy Grail" is also powered by the 5100 caliber. Its price is now skyrocketing and the quest to find one so difficult. The Mark 4.5 is the way to go to acquire an Omega watch with movement, before the price increases too.