Apart from Nikon's professional F series, two further Nikon camera series attracted much attention from about the end of the 1970s on: the FE (E for electronic) and the FM (M for manual) series. These two series developed a great reputation as small but rigid. The FE series was virtually discontinued with the arrival of autofocus cameras, but Nikon still manufacture the FM2. Apart from the Leica R6.2, the Olympus OM-3Ti, the Olympus OM-2000 and the Kiev 19M, it is probably the only mechanical 35mm SLR produced any longer.

In 2001, they presented a new product, the Nikon FM3A. It basically is a FM2 with an aperture priority mode added (thus having a hybrid manual/electronical shutter: manual in "M" mode, electronical in "A" mode) and a few other additions. So you have the advantage of manual shutter times if you run out of power or if the temperature is very low, and you also have the advantage of aperture priority and a center-weighted exposure meter when you want it (and the weather and battery want too *g*).

Now what so special with an expensive manual focus camera? First, it is supposedly as rigid as the famous FM2, second it adds the useful aperture priority which is more comfortable at handheld photography, third it enables you to use one of the most varied and huge selection of lenses (I personally use it with great but inexpensive lenses like those from the former Soviet Union), and finally it truly has many "professional" details.

It has a top shutter speed of 1/4000, a top flash synch speed of 1/250, a depth-of-field lever, indirect mirror lock-up via the (mechanical) self-timer, and much more. Some people would like to see it with spot metering, but I as being to used to handheld meters and exposure corrections am perfectly happy with center-weighted metering. Others even would like to see matrix metering in this camera, but as this metering system is totally inscrutable and uncorrectable, I wouldn't recommend it to any serious photographer. What is a bit "disappointing" is that the viewfinder only shows 93% of the full frame. Another interesting possible addition would be interchangeable finders (for being able to use a waist-level finder). Some people think it's a bit expensive (the - more expensive - black body costs about USD 610 in the U.S. or about EUR 910 in Austria), but on the other hand there are hardly any other camera bodies which have a longer average lifetime, so actually it is quite inexpensive for the ruggedness and reliability it offers! Other than that, it's probably impossible to make it any better! It is simply the climax of many decades of construction of mechanical 35mm SLR cameras.

FM3A vs. FA

advantages of the FM3A over the FA
The FA only has an ISO range of 12-4000 instead of the FM3A's 12-6400. The FA only has two manual shutter time back-ups: M250 and B, while the FM3A can create all shutter times manually. The FM3A offers two features over the FA: an AEL exposure lock button and a flash exposure compensation button.

disadvantages of the FM3A compared to the FA
The FA supports AI-S lenses of which's additional features the FM3A cannot make any use. The FA offers matrix metering in addition to center-weighted integral metering. The FA offers P and S modes in addition to the FM3A's A and M modes.

FM3A vs. FM2(n)

advantages of the FM3A over the FM2(n)
The FM3A offers an A mode in addition to the FM2's M mode. Its metering system has a metering range of EV 1-20 instead of the FM2's EV 1-18 range. The FM3A offers three features over the FM2: TTL flash exposure metering, an AEL exposure lock button and a flsh exposure compensation button.

FM3A vs. F3

advantages of the FM3A over the F3
The F3's highest shutter speed is only 1/2000 instead of the FM3A's 1/4000. It only has two mechanical shutter time back-ups: T and M60, while the FM3A can create all shutter times manually. Its flash synch time is only 1/80 instead of the FM3A's 1/250. Its metering range is only EV 1-18 instead of the FM3A's EV 1-20 metering range. The FM3A has a flash exposure compensation button which the F3 hasn't.

differences between the FM3A and the F3
The F3's center-weighted integral metering system is more concentrated in the center with 80/20 as opposed to 60/40. The F3's self-timer is quartz-controlled rather than mechanical.

disadvantages of the FM3A compared to the F3
The F3 can also use non-AI lenses which the FM3A cannot use. The F3 has a 100% viewfinder coverage instead of the FM3A's 93%. The F3 offers real mirror lock-up which the FM3A doesn't.

FM3A vs. Leica R6.2

advantages of the FM3A over the Leica R6.2
The FM3A has an additional Av aperture priority mode. The FM3A has a wider ISO range of 12-6400 compared to 12-3200. The FM3A has a shorter flash synch time of 1/250 compared to 1/100. The FM3A has a flash exposure compensation button which the R6.2 hasn't. The FM3A has a viewfinder coverage of 93% compared to 92%. The FM3A has a shorter shortest shutter speed of 1/4000 compared to 1/2000.

disadvantages of the FM3A compared to the Leica R6.2
The R6.2 has an additional selective metering (7mm circle). The R6.2 has a wider metering range of EV -1-20 compared to EV 1-20. The R6.2 has 5 exchangeable screens compared to 3. The R6.2 has a built-in diopter correction (+/-2) and a built-in eyepiece cover. The R6.2 offers true MLU compared to the FM3A's indirect MLU via the self-timer.

Links
interesting Nikon FM3A review by Josh Madison
good Nikon FM3A review by Chris Groenhout for Apogee Photo Magazine
brief Nikon FM3A review by Philip Greenspun for photo.net
short Nikon FM3A overview by Christoph Ozdoba [German only]
short Nikon FM3A overview by Peter Lausch [German only]
individual Nikon FM3A reviews at Camera Review
individual Nikon FM3A reviews at photographyreview.com