In my last post I discussed the benefits offered by “full-frame cameras”, defined therein as “… cameras that have sensors that are equivalent in size (dimensions) to 35mm film”. Today’s post will focus on the other side of the coin, that is, advantages of cameras with sensors that are smaller than 35mm film. These are collectively known as “cropped-sensor” cameras, and the higher the crop-ratio, the smaller the sensor becomes.
In this post, my predominant focus is on DSLRs with an “APS-C” sized sensor, which corresponds to a crop ratio of between 1.5 and 1.6, implying that a full-frame sensor would be around 1.5 to 1.6 times larger in surface area when compared to the cropped sensor. Here again, the “APS-C” nomeclature harks back to the time of film, whereby the APS-C format was a film-size that was roughly 25mm by 16mm in dimensions. Before we proceed, it needs to be clarified that there are even smaller sensors around, such as those found in cameraphones and compact cameras, but I won’t be going into the merits of such smaller sensors as of yet. Nonetheless, most points listed below can be extrapolated, to some extent, to cameras with such smaller sensors as well.
So – let’s get down to business. What are the benefits of smaller sensors over full-frame sensors? This post explores three primary benefits, namely (a) cost considerations, (b) weight considerations, and (c) reach. Here’s how.
Let’s start with an obvious difference. Cost. As a general rule, you can reliably expect to pay far higher prices for cameras with a full-frame sensor when compared to a crop-sensor camera. Given that money doesn’t grow on trees, this is a score in favour of crop-sensor cameras, of course. And it doesn’t start and stop exclusively with the camera bodies, as cost considerations also come into play when it comes to compatible lenses. For instance, whilst Canon cameras come in both flavours, full-frame and crop, not all (DSLR) lenses made by Canon would fit on its full-frame cameras. Indeed, lenses that fit on full-frame cameras are designated as being “EF” cameras, whilst those made exclusively for crop-sensors are designated as being “EF-S” lenses. As you might guess, EF-S lenses tend to be cheaper than their EF counterparts. This exacerbates the cost issue of buying full-frame bodies, since you can only use EF lenses on these bodies, as the cheaper EF-S lenses would either malfunction or return an unusable image if attached to a full-frame body. By way of example, Canon’s current entry-level full-frame camera (EOS 6D) costs nearly as much as Canon’s flagship crop-sensor camera (EOS 7D Mark II). However, when you add a general purpose zoom lens with an f/2.8 maximum aperture, the cost of buying full-frame exceeds the cost of crop (e.g. EF 24-70 f/2.8 II @ €1,700; EF-S 17-55 f/2.8 @ €680). (Costs increase considerably if you opt for a Canon EOS 5D Mark III, which offers similar performance specs to the 7D Mark II on many fronts, as opposed to the EOS 6D which is found lacking on several aspects when compared to the 7D II). The same argument applies to other brands, such as Nikon, for instance (vide debate of FX vs DX lenses).
A second advantage offered by cropped-sensor cameras is in terms of size and weight. You can also, generally, expect a size and weight advantage when using a cropped-sensor camera, as the smaller sensor allows for tighter (read, smaller) designs. Smallness implies lower weight and better comfort for the user. It might not seem apparent at first, but lower weight hanging from your camera strap or in your hands will be an obvious advantage when out shooting for a long period of time. For instance, a wedding gig could see you out shooting for anything between five to eight hours straight, and the extra weight of full-frame cameras and their (typically larger, and heavier) lenses will have you tire out quicker for sure. A tired photographer is generally less creative and less amenable, so in a way, (and yes I might be overextending here), you can also link cropped-sensor cameras to more efficient and effective photography in the long run! Joking aside, do consider weight and size if you intend to be out shooting regularly. I have to admit that, despite loving my new(ish) 5D Mark III, I did tire out far more quickly when using it on holiday last August. And to be quite honest, I don’t think the photos I achieved would have been significantly worse, quality-wise, if I had shot them with my (lighter) 70D. So there you have it, advantage (b) is out of the way too.
This brings us to (c) “reach”. This is the third advantage offered by a cropped-sensor body: it ‘extends’ the reach of your lenses to an equivalent higher focal length, with the ratio of extension equating to, (you guessed it), the crop ratio! For instance, whilst a 50mm lens on a full-frame setup would, unsurprisingly, render an image that is equivalent to the 50mm field-of-view, using this same lens on a cropped-sensor (1.6x) body would return an image with a field-of-view equivalent to an 80mm lens (50mm multiplied by 1.6). This is typically seen as an advantage of cropped-sensor bodies, as it ‘extends’ the (telephoto) usefulness of your lenses. It is an especially prized feature of cropped bodies amongst birders and sport photographers, since in such situations reach is paramount. This happens due to the fact that a crop sensor only sees the central portion of a (full-frame) lens’ image circle (that is, the projected image from the lens). In effective terms, seeing only this central portion is akin to having “zoomed in” on the central part of the full-frame image which one would have obtained using the same lens on a full-frame body.
Of course, it’s not always greener on the other side, and there are of course downsides to crop-sensor photography. Image quality, depth of field (and quality of bokeh), noise performance, etc are all issues mentioned in my earlier, full-frame advantages post. These full-frame advantages play to the weaknesses of cropped-sensor cameras, and indeed are the kind of advantages that justify extra costs, added neck strain (read, weight issues) and lower reach at the telephoto end.
Regardless, there is a role to play for cropped-sensor bodies and that is typically associated with the strengths of these three key advantages. In a nutshell, crop cameras tend to offer the best compromise between price and quality, and are due most of the credit of popularising DSLR photography amongst the masses. It is unsurprising that, for many, a cropped-sensor body would be the first DSLR ever bought, and for many of those, it would also be the last.