The term ‘full-frame' refers to a full-frame sensor that's same size as an individual frame of traditional 35mm film. The advantages of full-frame sensors over smaller digital camera sensors, such as APS-C or Micro Four Thirds are numerous.
For starters the larger surface area of a full-frame sensor means that the individual light-capturing photodiodes (pixels) can be larger, which in turn improves performance in low light.
Creatively speaking, another advantage of full-frame sensors is that it's possible to attain a shallower depth of field compared to their smaller-sensor comrades.
As a result, full-frame sensors are considered to deliver the very best in image quality, although they do feature high price tags and as a result you'll want to make sure you're picking the right full-frame DSLR for you.
Here's a selection of the best full-frame DSLRs of 2014 to help you decide.
Street price: £1400 body only
While the Nikon D600 represented a breakthrough for full-frame DSLR photography at a more affordable price, unfortunately it wasn't without flaw.
A substantial number of users reported that after around 3000 shots they noted the appearance of dust spots on the camera's sensor.
As a result, Nikon swiftly followed the launch of the Nikon D600 with the Nikon D610 - a model which offers much of the same specification and features but with an all-new shutter mechanism.
As you would expect the D610 offers similarly impressive image results and general performance, both of which arrive at a price within the reach of the enthusiast photographer.
Best full-frame DSLR for: High-end full-frame affordability
Street price: £1400 body only
The Canon EOS 6D is, in many ways, Canon's riposte to the Nikon D600.
Smaller than other Canon full-frame DSLRs, the 6D is built around an all-new 20.2MP CMOS sensor and Canon's powerful DIGIC 5+ processor - the same one that's used in the 5D Mk III.
This allows it to offer the same sensitivity range as the Mk. III, namely from ISO 100-25,600 (expandable to ISO 50-102,400. Continuous shooting speed is a little slower though at 4.5fps (compared to 6fps).
Elsewhere, the 6D does compromise a bit, no doubt in order to keep costs down. For example, the AF system is made up of just 11-points with only one cross-type sensor in the middle. One notable inclusion on the 6D that isn't found on Canon's more expensive DSLRs is built-in Wi-Fi connectivity.
Best full-frame DSLR for: Entry-point to full-frame Canon photography
Street price: £2300 body only
The 5D Mk II was already a class act, and with the 5D Mark III Canon has really pushed the boat out.
While the new model only gets a marginal increase in resolution - from 20MP to 21.1MP - the sensor has been completely redesigned with gapless microlenses for improved low-light performance.
Add to this improved AF, increased sensitivity range, faster burst shooting, and improved HD video recording and the 5D Mark III adds up to a full-frame heavyweight.
Best full-frame DSLR for: Videographers
Street price: £5200 body only
If you want the very best in terms of all round performance, both with regards to image quality and general performance, it's difficult to see past the Nikon D4S.
The model delivers some eye-watering statistics - 10fps for other 100 Raw files; maximum ISO of 409,600; Over 3,000 shot battery life; 3.2in LCD screen.
Although it's one of the largest DSLRs on the market, the level of performance makes it all worthwhile and if you're a professional - or just got a few quid to spare - the Nikon D4S is on of the best going.
Best full-frame DSLR for: Pro-level performance
Street price: £4850 body only
Broadly speaking, the basic aim of the 1D X was to take the studio-friendly resolution offered by the 1Ds Mark III and combine it with the speedy-shooting capabilities of the (APS-H equipped) 1D Mark IV.
To this end the 18MP 1D X is a big success; equipped with twin DIGIC 5+ image processors the 1D X boasts a top burst speed of 12fps - or 14fps if capturing JPEGs only.
Add to this a standard sensitivity range of ISO 100-51,200 (50-204,800 in expanded mode), a 61-point AF system of which 41 are cross-type sensors, and enhanced Full HD movie recording abilities and there's no doubting the 1D X's credibility as a serious tool for professional photographers.
Best full-frame DSLR for: Canon professionals
Street price: £1600
Sony broke new ground at towards the end of last year with the launch of the Alpha 7 and 7R. The models are the first compact system cameras to feature a full-frame sensor.
Although the Alpha 7R is a CSC and not a DSLR, with a resolution of 36.4MP it's placed in line with some serious high-end competition.
As you would expect for a CSC, the Alpha 7R is compact and portable, making it the perfect option if you're looking for full-frame photography in a portable body.
Best full-frame DSLR for: A CSC alternative