Ok folks, I’m going to keep this short and sweet! Let’s cut to the important facts.

Preamble:  I’ve shot extensively with Canon, Nikon and Sony gear (not sponsored by any of the three).   Ergo, I know these manufacturers & have no particular horse in the game.

DSLR History

For several decades Canon and Nikon have been duking it out, with Nikon firmly gaining the upper hand.  While each has similar deep collections of quality glass, Nikon cameras in general offer approx. 15 stops of dynamic range with Canon only 12-13. For most nature photographers, dynamic range is critically important.

Additionally, Nikon’s latest consumer flagship the D850 is a great sports/birding camera with the ability to expertly focus/track moving objects.  Couple that with a fast 7/sec frame rate and this camera can do it all.  Canon’s 5D Mk IV can’t focus lock/track sufficiently well and has a painfully slow frame rate (with a buffer that almost immediately bogs down).

Why are people moving to mirrorless?

  • They are smaller & lighter. The average full-frame mirrorless is ½ the size of the D850 and approx. 2/3 the weight.
  • They offer digital viewfinders that allow on-screen histograms & exposure warning indicators(ex. zebra lines below show overexposure). For advanced manual shooters, getting the exposure dialed in becomes faster/easier.
  • They offer focus peaking, a feature that allows you to quickly determine which portion of the photo is in focus as you modify the aperture setting. Ex. rider on right is shown highlighted in red (in focus). Note: It’s close, not perfect…you still need to double-check.
  • No need to bother with mirror lock-up with long exposures (no mirror!).
  • Ditch your reading glasses. The digital viewfinder can be adjusted to your prescription.

Nikon’s mirrorless Z6 and Z7 options

  • At 25 & 46 MP these cameras offer good resolution and the same dynamic range as the D850.
  • They offer great, in viewfinder, histograms, exposure warning and focus peaking.
  • They can’t lock on/track moving objects well & have slow frame rates (buffers that rapidly fill and slow your shooting to a crawl). Ergo no good for sports/bird photography.
  • Lousy lens selection. Your old Nikon DSLR glass won’t fit the Z series camera without using an adapter that adds 1 inch to the lens length.  So much for a smaller camera. The only zoom lenses that are currently offered to work directly on the Z series camera are a 14-30mm and 24-70mm.
  • Only one card slot.

Canon’s mirrorless R series option

  • 30MP offers reasonable resolution, however, the camera is rumored to offer only 13 stops of dynamic range.
  • Same histogram, exposure warning, and focus peaking as Nikon.
  • Lousy focus lock/tracking and even worse frame rate. Only 2-3 shots/sec when tracking moving objects. Also no good for sports/birds.
  • Lousy lens selection. You either use one of two adapters for older Canon lenses, or have the limited choice of a 24-105mm zoom that’s compatible with the R series camera.

Sony A7 series

  • The company has a 7-year head start on mirrorless technology over Nikon/Canon.
  • The new A7r IV offers a whopping 63 MP, 15 stops of dynamic range and weather sealing equivalent to the D850. The earlier generation A7r III (@ 43MP) and A7 III (@ 25MP) offer strong lower-priced options. (see discussion below for further detail).
  • All the in viewfinder options (histogram, exposure warning, and peaking).
  • Focus lock/tracking that bests the D850 and a superior frame rate of 10 shots/second. Great for sports/birding.
  • Great lens selection and quality. Sony lenses are shorter than Nikon/Canon DSLR lenses, generally lighter and have better sharpness edge to edge (see DXO testing scores below).  They also are the only manufacturer to offer a programmable lens button that allows side button focusing, a game-changer for sports or bird shooters.  Ergo, use your left hand to focus on moving objects, use your right to depress the shutter.  Improved my hit ratio 100%.
  • Manual focus option that allows 3/1 magnification of center spot to quickly achieve critical focus. Great tool for focus stacking.
  • Word of caution, the on-screen menus aren’t optimal. They could use a little better organization/simplification.

Tale of the tape:

Sony details

  • The new A7r IV’s chief advantages over the A7r III include greater resolution, weather sealing, and improved ergonomic grip. The A7 III, while offering lower resolution, has considerably better low light performance given lower pixel density (generates far less noise at higher ISOs). Ergo, I use it as a backup camera and in situations where I’m forced to shoot at a high ISO.
  • Which camera to use for sports?  While the A7r IV has a fast frame rate, the massive 62 MP file size quickly fills up the buffer shooting sports.  The only realistic option is to switch the camera to APC mode (crop sensor size) and shoot 26MP images.  This allows great reach with your glass (1.6 crop factor plus the buffer won’t fill).  The other strong choice to use for sports is the A7 III.  With a smaller full frame sensor (25MP) the camera’s buffer won’t fill up, plus it’s low light ability (with lower pixel density) easily bests the A7r III or IV.  The A7 III (like it’s big brother the A9 is the clear winner when shooting sports indoors or in low light).
  • Which to use for birds/wildlife.  The A7r IV has the edge here offering slightly superior focus tracking to the A7III.  APC mode allows you to get more reach from your glass.  You’re typically not firing off photos so fast that the buffer bogs down.
  • How to set up your A7r III or A7r IV. Don Smith offers some great instructional videos.
  • Increasing the viewfinder gain for low light: A great option for focusing in very low light (great for celestial photography). This makes the image so bright you can actually see the Milky Way live on screen!  Makes focus peaking a snap.
    • Here’s how to use.  Activate the manual focus on your lens and focus peaking.  Go to the custom key setting in your camera’s menu and under custom button 2, scroll through the menu and select “bright monitoring”…select.
    • Then when you have a situation where you need to brighten up your monitor in manual focus mode, just push the C2 button atop your camera to activate Bright Monitoring.  Depress the button again to turn off.


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