This is one of the more frequent themes of conversations I find myself in with photographers who are trying to make their way through the incredible range of equipment available to image makers today. As common a concern as it is I have yet to come up with a more satisfying answer than “it depends.” With the inherently technical nature of photographic equipment its natural to expect that one could simply compare specifications and determine an objective best. In my experience however, the subjective preferences of the practitioner and their requirements for the final image make it impractical to give a universal recommendation for which camera may be best suited to your endeavors.
Each sensor format has its own strengths, and each system has its own potential pain points to take into consideration. So the answer is, depending on the photographer, yes, no, and maybe. Each format needs to be analyzed against your personal needs and preferences to make an informed decision.
Take for example, some of the most noticeable performance differences between different sized sensors. Larger sensors tend to capture a greater dynamic range, exhibit less noise and allow for greater pixel density relative to smaller sensors. These traits may allow you to retain more tonal information in the extreme highlight and shadow regions, allow you to use higher ISO values with less image degradation and allow you to record a greater degree of detail. Why then would anyone make use of a smaller sensor?
As sensor size increases so too does the camera body housing it along with the lens projecting onto it. For many, the possibility of scaling down the size and weight of their equipment is reason enough to choose a smaller format camera. Equipment expense can vary between formats as well, with the larger full-frame models typically at the higher end of the scale.
Full-frame cameras will also require lenses with full-frame coverage to make full use of those larger sensors, whereas smaller format cameras can potentially make use of both their native coverage lenses as well as larger format lenses. Larger sensor cameras can also utilize a wider angle of view than smaller sensor cameras through the same focal length lens and will exhibit a narrower depth of field than smaller sensor cameras when comparing equivalent angles of view from the same shooting position.
In practice, this allows smaller sensor cameras to achieve equivalent framing with a smaller lens than what a full-frame camera would require. Take for example, the Art 30mm; this lens was designed specifically for the APS-C format cameras (denoted as DC in the Sigma lineup) and yields a field of view equivalent to the full-frame coverage (denoted as DG) Art 50mm at nearly half the size at weight. This principle applies when utilizing full-frame coverage lenses on APS-C cameras too. Take for example the Contemporary 100-400mm; when this DG lens is utilized on an APS-C camera it yields a field of view equivalent to that of the Contemporary 150-600mm lens utilized on a full-frame camera while weighing 1.7lbs less. Now of course this principle applies to the 150-600mm lenses as well, utilizing one of these lenses on an APS-C format camera yields a field of view equivalent to a 225-900mm lens, a focal length range you simply won’t find available for full-frame format cameras.
How does any of this help to make sense of whether or not a full-frame camera is necessary to improve your photography? To very broadly summarize, if all-out image quality is more important than physical size or cost, if you primarily photograph with very narrow depth of field, if you primarily photograph in extreme low-light conditions or if you want to have access to the largest group of high-performance wide-angle lenses you might be destined for a full frame camera. If you work primarily in good light, if you primarily photograph distant subjects and want the greatest degree of apparent magnification, if you’re looking to reduce the size and weight of your equipment or if you’re looking to moderate your equipment expenses you may be better suited by going with a smaller format APS-C or Micro Four-Thirds camera. And here’s the good news: Whatever sensor size system you choose, Sigma offers a great selection of lenses.