Mirrorless or DSLR? Part-2

DSLR Autofocus

A complete discussion of this topic could be a whole article in itself. I'm just going to discuss the salient points of comparison between the two systems. It seems like this feature has been around forever, but the first autofocus film camera was only introduced in 1985 on the Minolta Maxxum 7000. Since then, the camera makers have been honing the system into what we have today. All of that refinement is a good thing. If you're looking for reliable and time-tested autofocus performance, a DSLR is you best bet. This is especially true for sports and wildlife photography.

There are some shortcomings you should be aware of. The autofocus system actually has a completely different sensor than the imaging sensor. When you look through the viewfinder, some of the light is being redirected to this other sensor which has specialized pixels designed specifically for focusing. For this to work, the distance from the lens to both the autofocus sensor and the main sensor have to be exactly the same. Even a microscopic discrepancy causes problems. This is more critical at fast f-stops (e.g. f/1.4) for two reasons:

1. Depth of field is smaller, so focus distance errors are more obvious.

2. At fast f-stops the cone of light coming from the lens to the sensor is steeper. This means the critical focus area is much smaller.

Lens aberrations can also cause errors. To correct this, users must make micro-adjustments to each lens / camera pair to get perfect focus. This problem is more likely to be noticed by more advanced users. Astrophotography is especially unforgiving because distorted stars are very obvious in a photo. I don't want to overstate this issue. Most of the time the performance of this system is perfectly fine. But wouldn't it be nice if the problem didn't exist at all?

Mirrorless Autofocus

Autofocus speed has been one area where mirrorless cameras have had to play catch up. Early cameras only had contrast detect autofocus modes. In this mode, the camera doesn't know if the focus distance is too short or too long, so it has to hunt back and forth testing contrast until it figures it out. This could take literally seconds in some cases.

Newer mirrorless cameras have phase-detection autofocus built into the main sensor. In fact, the Sony A7R mark-2 has 399 autofocus points, far more and better coverage than any DSLR camera (The Nikon D810 has 51 focus points, for example). These new cameras focus just as fast as their mirrored counterparts. Several mirrorless systems have added face detection and even eye detection to their focus systems--very useful for portraits.

Finally, the problem of having to micro-adjust lenses is not present in mirrorless cameras because the imaging and the focusing are both done on the same sensor.

What's the overall conclusion on autofocus? The mirrorless cameras have largely closed the gap, but it's still a work in progress. Professional sports and wildlife photographers will want to stick with DSLR's for the time being. For other types of shooting, both systems work well. If you're considering buying a mirrorless, it's worth researching if it has phase detect autofocus (PDAF).

Durability

Here is an important issue to consider: what environment will the camera be used in? Do you plan to take it out into the weather? How much will it get banged around? Landscape photographers take their cameras out into sun, sand, wind, rain and snow. Will the camera survive these conditions?

Professional level DSLR's are built like a tank. They have good weather sealing, the buttons are very durable, and they can take a fair amount of punishment. And there is no fragile flip out screen to get bent or broken. In general, DSLR bodies are larger and stronger so they can support large, heavy lenses. The larger base also provides a more solid connection to a tripod or L-bracket. The heavier body also balances in the hand better with larger lenses.

I'm generalizing here, but most mirrorless cameras are less durable than the pro-level DSLR's mentioned above. Of course, this is highly dependent on the camera in question. And many professionals use mirrorless for landscape photography. In the end, it comes down to how well you think you can protect the camera.

Can you use larger lenses with mirrorless cameras? This is usually not necessary, as mirrorless lenses are designed to be smaller and lighter. Larger lenses (e.g. 70-200mm zooms) are supplied with a collar so the lens can be mounted directly on a tripod. This means camera doesn't have to support the weight. Where this is more of a problem is when DSLR lenses are adapted for use on a mirrorless. In this case, the adapters themselves often come with a tripod mount (either a standard mount or a arca-swiss style dovetail) so that the adapted lens can be mounted to the tripod if necessary. This is a bit of a hassle though, as it's much more convenient to be able to switch lenses without taking the camera off the tripod.The Sony A7r-mark 2 and the new A6300 bodies have been strengthened for the purpose of being able to use heavier lenses. Sony knows that many Canon users mount their lenses on this camera, and so they designed these new cameras to be more compatible with adapted lenses.

System Longevity

When you buy a camera, you are also buying into an entire ecosystem of lenses and accessories, the price of which often exceeds the camera itself. Technology moves fast, and after two or three years you may want to upgrade the camera body. Good quality lenses usually last a long time and don't need to be upgraded. You want to know that the company that makes the camera will continue to support the system. You want the company to be able to repair the camera, and you want the option of upgrading the camera and lenses at some point in the future.

You want the company you buy from to be stable and reliable. For this reason alone, Canon and Nikon look like good choices. Surely they aren't going anywhere, and that's probably correct. But one note of concern is that DSLR sales are falling sharply. In 2015, the DSLR market dropped fifteen to twenty percent, and not coincidentally the mirrorless market grew by about the same amount. The industry is clearly in transition, and which companies are more likely to stick around, the ones making money or the ones losing money?

Conclusions

There is no one right camera for every situation. Cameras are optimized for different purposes, preferences, and budgets. And to make the situation more complex, the landscape of camera choices continually shifts as new lenses and camera bodies are released. This week brought the introduction of the Sony A6300 which is able to simultaneously display a live view through the electronic viewfinder, continuous focus and capture eight frames per second. The live-view-while-shooting feature is a first for mirrorless cameras, and it addresses one of the obvious shortcomings of mirrorless systems--that while continuous shooting, you couldn't visually track a subject.

If you're in the market for a camera--and the ecosystem that goes with it--which should you choose? The most important factor is what subjects you intend to shoot:

Sports and Wildlife

As of this moment, the autofocus systems on mirrorless cameras are not as fast, reliable and consistent as the DSLR's. Mirrorless cameras are catching up in terms of speed, but experienced photographers still wrestle with the controls to get these cameras to autofocus where they want. Add to this the fact that there are very few super-zoom lenses available for mirrorless systems, and you can see that the best choice is an APS-C or full frame DSLR for this type of shooting.

Wedding and Portrait

This is a tough call because there are so many tradeoffs. A wedding photographer will often have two or three cameras hanging from her neck or a belt strap. With DSLR's this can be very heavy and bulky. For this reason some wedding photographers have switched to mirrorless. Many mirrorless cameras can now shoot without shutter noises which means the photographer is not interrupting the ceremony with flurries of clicking sounds. However DSLR's have the advantages of longer battery life, dual card slots, and the durability to make sure you get the shot during this one-time event. For portraits, DSLR's often have better support for sync'ing and controlling remote flashes / strobes. As for autofocus, the mirrorless systems have face and eye detection which can be very useful. However, the DSLR autofocus systems tend to be more predictable.

Street Photography

Mirrorless is the obvious choice here. The cameras are smaller, stealthy and discreet. If you walk into a crowd with a massive professional DSLR and and a monstrous piece of glass, you are sure to make people nervous. With a mirrorless camera, you're just another tourist taking snapshots.

Landscapes

This is another tough call. Currently this area is dominated by full frame DSLR's. There are photographers--including professionals--who are switching over. The DSLR systems have a larger lens selection. The most compelling advantage to mirrorless is the what-you-see-is-what-you-get nature of working with an electronic viewfinder. You see the white balance and exposure *before* you take the shot, instead of peering through the glare at the back of a DSLR screen. There is also (usually) a weight advantage. When you are carrying around a camera and selection of lenses for five hours or more, some weight savings is greatly appreciated.

Final Thoughts

At this point in time, I could make a case for either camera style. If you want a camera that does everything well, then a DSLR is a good choice. It's been said that the best camera is the one you have with you. In that case, the more portable mirrorless might be a camera you have with you more often. Does the fact I'm not recommending mirrorless for wildlife mean that you can't use one for that purpose? Of course not. I've taken plenty of wildlife photos with my Sony. It just happened to be the camera I had with me when I stumbled across some beautiful animals. All it means is if wildlife is your *main interest* that a mirrorless camera may not be optimal.

In the next few years, it's likely that nearly all of the camera market will have switched to mirrorless. DSLR sales are dropping as mirrorless sales keep rising. Going mirrorless has disadvantages, but as the technology advances, those disadvantages keep disappearing.

Does this mean you should hold off on buying a Nikon or Canon? I think the best approach is to buy what best meets your needs now. Rumors say that both of these companies are going to enter the mirrorless market within the next six to nine months. You can bet that those cameras will be compatible with the huge selection of lenses available for those systems.

Maybe the best solution is to buy both a mirrorless camera and a DSLR!