The DSLR – digital single reflex camera – was king until mirrorless digital cameras first began to appear in the late 2000s. Mirrorless models immediately shook up the scene, and while professional photographers continued to lean towards the familiarity of the DSLR, many casual and hobbyist users began to opt for the smaller, lightweight mirrorless models. It was the beginning of the DSLR vs mirrorless debate – could a mirrorless, interchangeable lens camera really produce the same quality of images as a DSLR?
Over the years the technology has evolved, and investment in mirrorless cameras has grown. The line between the two has blurred, and many pros can be seen opting for mirrorless equipment especially as companies like Canon, Nikon and Sony have produced pro-level mirrorless bodies and exceptional lenses to attach to them. As mirrorless options have become more widespread, they’ve become the target of the most up-to-date technology, while DLSR units – although still trustworthy and high-performing – are sporadically updated, with the release of new models now rare.
Either makes a great choice for astrophotography, but there are some differences that you should be aware of, which is where this article comes in. We also have a beginner’s guide to astrophotography, for anyone looking for pointers on settings and location choice. And if you’re wondering, we also break down the best cameras for astrophotography, which includes a mixture of mirrorless and DSLR models.
What’s the difference between DSLR and mirrorless?
There’s a fundamental difference between the two types of camera, and it comes down to the path the light takes from the back of the lens to the sensor. DSLRs use the technology of old film cameras, where the light enters through the lens and hits an angled mirror, before being reflected up and bounced around in a prism into the optical viewfinder. This is how the photographer sees directly down the lens. When you press the shutter button, the mirror lifts to unveil the image sensor. Part of the ‘click’ you hear is the mirror moving out of the way, ready for the image being projected onto the sensor to be captured as the mechanical shutter opens.
Mirrorless cameras, as you might expect, don’t have this function. Instead, the light enters through the lens and is projected straight onto the naked sensor, which sends it live to the viewfinder, which is a screen, or to the screen on the back of the camera. There’s still a mechanical shutter in some models, but others make a noise through a small speaker to let you know an image has been taken.
The size and weight difference between DSLR and mirrorless
DSLRs are often branded as the heavier option – while mirrorless cameras have a reputation for being a smaller, lightweight alternative. Put them side by side and this certainly can be the case – digital SLRs are larger than film cameras used to be, and suited to professionals who lug around heavy gear as standard. Mirrorless cameras appeal to beginners and intermediate users, who don’t care for the hassle that comes with heavy equipment.
This is changing, however. Mirrorless cameras now appeal to customers at all levels of expertise, meaning some high-end options – such as the Panasonic Lumix S1 – are just as large and heavy as their DSLR counterparts. One of the reasons for this is that larger sensor sizes have grown in popularity, with full-frame units (those with a sensor the same size as a frame of 35mm film) leading the market. The matching lenses also tend to be bulkier. Smaller, lighter weight cameras, such as Olympus or Fujifilm models, are a good option if size and weight are a priority.
Lens options and availability
DSLR brands such as Canon, Nikon and Pentax offer everything from telephoto 800mm and 600mm to wide-angle 12mm to 24mm lenses, with third-party manufacturers – such as Sigma, Tokina and Tamron – making lens options more affordable. Popular mirrorless lens needs are covered well too – with only the rarer lens requests being harder to source. The mirrorless market is growing constantly, so if there is a lens missing for your chosen brand, it likely won’t be long until the gap is filled. You can also often use DSLR lenses on mirrorless cameras by investing in an adaptor.
If you want to use your camera in conjunction with one of the best telescopes, then you’re in luck, as either kind can be attached with the help of adapters.
Rigorous testing shows DSLRs offer better battery life, sometimes allowing up to double the number of shots in one charge. This is simply because DSLR batteries are often bigger, holding more power, and the electronic viewfinders and increased screen use on the mirrorless cameras drain the battery quicker. If your heart is set on mirrorless, and you are likely to use your camera for long periods each day, the easiest solution is to carry a second battery, either in your pocket or in a special battery grip – or invest in a battery pack and charge your camera over USB – many mirrorless cameras offer this option, but it’s rare in DSLRs.
The professional favorite DSLR, the Canon EOS-1D Mark III, shoots at 16 frames per second (fps), flipping its mirror out of the way every time. This is boosted to 20fps if you lock the mirror up and use an electronic shutter. Meanwhile, current top-level mirrorless cameras shoot at 20fps, or even 30fps, as standard. Some mirrorless models claim a 60fps speed using an electronic shutter, however these set the focus at the first shot and can cause banding to appear on the image. Nikon’s remarkable Z9 offers 120fps, if you don’t mind a stream of 11MP JPEGs.
Autofocus and video
DSLRs have long been the go-to for precision and autofocus quality, but mirrorless technology is beginning to beat them at their own game. Mirrorless cameras tend to offer more focus points than a DLSR, and usually with points positioned closer to the edge of the frame – a particularly valuable feature when photographing in low light, people or wildlife. The silent shooting ability is handy, too, though watch out for the ‘rolling shutter’ effect that can make moving objects in the shot look very strange.
For many years, Canon has led the way in video making with DSLRs, with the 5D series being a particular full-frame favorite with professionals, and its crop-frame models being popular with vloggers and YouTubers. While 4K video is now the norm on high-end DSLRs, the quality of video is rapidly increasing on their mirrorless counterparts – with some newer models offering 6K or 8K, a rate DSLRs simply can’t match. In addition, mirrorless technology offers a trustworthy live autofocus, making filming much more user-friendly for the user. Some mirrorless cameras, such as the Canon EOS R5c and Sony A7Siii, are oriented more toward video work than stills photography.
Other important features
When it comes to the basic functions, DSLRs and mirrorless are neck-and-neck. The image stabilization function on DSLR lenses is matched on mirrorless bodies by an in-body image stabilization system (IBIS) that moves the sensor to compensate for camera movement – and some mirrorless lenses have stabilization too, which works with IBIS for a stronger effect. DSLRs and mirrorless cameras both allow the user to photograph in either JPEG or RAW formats and retain complete manual control over exposure settings, or go into full automatic and let the camera decide.
With fast continuous shooting, up to 8K video frame rates, high ISO and a live monitor with the possibility of overlaying histograms and gridlines on top of any video or image – mirrorless processing certainly trumps the DSLR. That said, the experience and trustworthiness of long-standing camera technology can’t be substituted, and the DSLR has the advantage of a longer battery life coupled with tried and tested quality.
Entry-level mirrorless cameras and DSLRs have come down in price and are now very affordable, but don’t expect them to offer high-end features
As with most technology, both types of cameras see their prices reduce as newer, more efficient models are released. However, we know this is likely to happen far more frequently with mirrorless cameras than with DSLRs, as fewer new models of the older technology are being released. Professional-level cameras tend to sit around the same price bracket anyway – with little difference between the types.
In terms of the price of lenses, which can often be the largest expense, you’ll find that mirrorless lenses are slightly more expensive, and there’s a smaller pre-owned market for them, which does keep the MSRP high.