Mirrorless or DSLR? Part-1

Mirrorless or DSLR?

This is a serious and difficult question, especially for photographers with no experience with mirrorless systems. When you buy a camera you are also buying into an ecosystem of lenses and accessories that represent a substantial investment. So it's worth the effort to make a good decision up front. Unfortunately, there is no obvious right answer.

Mirrorless is a paradigm shift that substantially changes the design of the camera. It allows the cameras and the lenses to be more compact. Many photographers, including professionals are trying to figure out if going mirrorless is better or worse for the type of photography they’re doing. The mirrorless landscape has also changed rapidly in 2015.

I own both a Nikon D810 and a Sony A7r, along with an odd assortment of other cameras including Canon, APS-C, film, astronomy, etc. What's interesting about the D810 and Sony A7r is that they share (nearly) identical full-frame, thirty six megapixel, Sony sensors. As you’d expect, the images that come out of these cameras are basically the same. This has given me the opportunity to see which design works best for that sensor. With a year of shooting with these cameras, I’ve had plenty of time to get a feel for their strengths and shortcomings.

Before we dive into the details, let’s revisit some claims about mirrorless cameras to see if they still hold true.

1. With mirrorless you have to compromise on image quality

The early mirrorless cameras were micro four thirds format or APS-C. Generally cropped sensors are not going to be able to perform as well as their full-frame cousins. There simply wasn’t a pro-level, full-frame mirrorless camera on the market. Going mirrorless meant going with a smaller (and presumably lower image quality) sensor. Sony put this one to rest with the A7 line of full-frame mirrorless cameras. The new Sony A7r Mark-II has a 42 megapixel back side illuminated (BSI) sensor that currently holds the top score on DxOMark. The Nikon D810's sensor comes in a close second.

VERDICT: No longer true. You don’t have to give up image quality.

2. Mirrorless cameras have a limited lens selection compared to DSLR’s

There is no denying this. There are literally hundreds of lenses for the DSLR systems. You can buy from the name brands (Canon, Nikon…) or from many third party manufacturers (Sigma, Tamron, Tokina…) Competition between the brands means there is a good selection of lenses at different focal lengths, prices and performance levels.

The situation on the mirrorless side has been getting much better—to the point that this may not be much of an issue now. The camera brands have been building out their lineups, and there is now third party support. Using the Sony full frame (E mount) lineup as an example, Sony makes lenses: 16-35mm, 28mm, 35mm, 55mm, 24-70mm, 90mm macro, 28-135mm, 24-240mm, and 70-200mm. The 16-35mm, 28mm, 55mm and 90mm are remarkably good lenses. One reviewer compared the A7r Mark-II with the 90mm macro to a Phase One 160 medium format camera with a Mamiya 120mm macro lens. His conclusion was that the Sony matched the Phase One pixel for pixel, and even came out on top in some cases. Zeiss also makes the superb Batis and Loxia lenses for the Sony E mount. These are pro-level lenses without question. For more budget conscious buyers, there are manual-focus Rokinons, that are surprisingly good optically.

Another thing to consider is that DSLR lenses can often be adapted and used on mirrorless cameras. For example, I currently use the (epic) Canon 11-24mm on the Sony A7r, and it works fine with autofocus, aperture control, EXIF data, etc.

Ultimately, you don’t need or want hundreds of lenses. You just need them in the focal lengths you shoot. The glaring hole in the mirrorless lineup is the in the super-telephotos. If you want a 150-600mm Tamron, the best you can do is buy the Sony DSLR version, and use a Sony adapter. The reason is that mirrorless cameras are not the weapon of choice for sports and wildlife—more on this in a moment.

VERDICT: True but much less of an issue unless you need super-telephoto focal lengths.

3. Mirrorless cameras are lighter, smaller and cheaper?

The camera landscape has been changing and the recent full-frame mirrorless are still smaller, but the weight on some models is getting close to the DSLR’s. Even so, I'd argue that the whole mirrorless system--camera and a set of lenses--is lighter overall. The new cameras are not cheaper though. At launch the Sony A7r Mark-II was $3200, just a couple hundred shy of the Nikon D810.

VERDICT: It depends on which camera you get. High end models are creeping up in weight and price.

4. The battery life is shorter on mirrorless

This is true. Because mirrorless cameras are smaller, they tend to have smaller batteries. It’s really not a problem to keep a spare battery in your pocket or backpack. It’s the price you pay for having a smaller, lighter camera and the extra functionality that comes with an electronic viewfinder. The Nikon D810 eats batteries just as fast if you use Live view for focusing. I don’t know of any serious photographers that don’t carry a spare battery anyway. With the Sony A7r, I can shoot for a solid three to four hours before I have to switch batteries.

VERDICT: True but not a problem.

EVF or OVF?

Mirrorless cameras use an electronic viewfinder (EVF) instead of a mirror and pentaprism. This difference is at the heart of the major tradeoffs between the two. The image through an electronic viewfinder has to be processed and displayed by the camera's electronics. This causes a small amount of delay in presenting the image. For sports or fast moving wildlife, that small delay can make a huge difference. My friend Liz Muraoka shoots dragonflies that dart in almost random directions as they fly. Catching one in-frame is hard enough without an artificial delay. The same can be said for sports, where you need to track the action at critical moments. If sports or wildlife are your primary subjects, then you should get a DSLR. The optical viewfinder is optimal for these subjects, and you will also have a good selection of long lenses to choose from. The lag has been coming down as the cameras get faster. However, if display lag is not an issue (e.g. shooting landscapes) then there are big advantages to having an EVF.

Here is a frequent occurrence with DSLR’s. You take an exposure, look at the LCD, and notice that it’s completely messed up. It’s bright blue because the white balance is off, or it’s too dark or too bright. Nearly the whole photo is blinking because it’s so badly over-exposed. This doesn’t generally happen with mirrorless cameras. The image you see through the viewfinder is what the camera will record. If the exposure or white balance is off, you notice *before* you take the photo. You can also watch a real-time histogram as you change exposure settings. Electronic viewfinders display zebra patterns superimposed on over-exposed or under-exposed parts of the image. For manual focus, you can turn on focus peaking (little red blips on sharp contrast areas)—great for checking depth of field. As soon as you turn the focus ring on the lens, the display zooms to 100% and you can pan around to check focus on different parts of the image. For portraits, the viewfinder shows green squares around the faces (or even the eyes) of the person it’s focused on. All these things are useful, save time and prevent missed photos.

For reviewing images, an electronic viewfinder is like your own private movie theatre. You can flip through images, zoom in and out, and pan around. Need to check the sharpness in the corners? No problem.

You can do many of the same things with Live View on a DSLR. But if you're like me, it's hard to get close to the little screen without reading glasses (age happens) and you have to shade the screen with your hand to reduce reflections and glare. A Hoodman (a rubber hood with a loupe-like lens) solves the magnification and glare issues, but it's clunky compared to simply looking through the viewfinder.

In Part-2, I'll cover focusing differences, durability, system longevity and some conclusions.