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 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 & Z7(I and new v II) 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.
  • The first-gen Z cameras can’t lock on/track moving objects well. While recent software updates have improved focus performance, their still not up to sports/bird photography. The same is true for The Z6 II & Z7 II which track slightly better.
  • The first generation Z’s also have painfully slow frame rates (buffer that rapidly fills and slows your shooting to a crawl). The new Z6 & Z7 II can shoot a respectable 12 pics/sec when in tracking mode.
  • Slim lens selection. Your old Nikon DSLR glass, is not nearly as sharp as new mirrorless lenses and 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 selection of Nikon mirrorless glass is pretty limited at the moment. Some of these lenses are great, some are lacking in IQ.  Ergo, lens selection requires careful study (buyer beware).  Nikon currerntly refuses to work with third-party lens manufacturers on mirrorless options.  It’s Nikon lens or nothing.
  • Only one card slot.

Canon’s mirrorless R series option

  • The new R5 (45 MP) and R6 (20MP) offers the same histogram, exposure warning, and focus peaking as Nikon.
  • Unlike the Nikon however these cameras offer outstanding focus lock/tracking and a good frame rate.
  • Limited but rapidly growing lens selection. The lenses are expensive (most $2,000+) but tack sharp. You either use one of two adapters for older Canon lenses.
  • The big problem is mediocre dynamic range (13.5 stops) and poor ISO invariance (2.5 stops vs 5 for Sony & Nikon).

Sony A7 series

  • The company has a 7-year head start on mirrorless technology over Nikon/Canon.
  • The new A7r IV offers a whopping 61 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).  Unlike Nikon & Canon they also 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%.
  • Very strong third party lens options.   Although the Sony 16-35 F2.8 is unsurpassed in IQ, the Tamron 17-28mm F2.8 is excellent as well and slightly sharper and lighter (14 oz vs 1.5 lbs) than the more expensive Sony 16-35mm F4.  Sigma’s 100-400 F5-6.3 provides similar IQ as the 2.5X more expensive Sony F4.5-5.6 100-400. It also has a programable side button & is slightly lighter (2.5 vs 3.1 lbs). Pros and serious amateurs may opt for the Sony which has better focus lock/tracking for sports/moving bird photography.
  • Battery life:  The Sony battery gets 670 shots with the LCD & 530 shots looking thru the EVF.  The Canon and Nikon only 320 and 330 thru the EVF.
  • 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.
  • For sports/wildlife/birding pros:  Sony today (1/26/21) announced the new Sony Alpha 1.  50mp, 30 frames/sec.  The world’s best focus tracking system.  @$6,500 it has no peers.

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.
  • 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 or birds due to its unparalleled object tracking).
  • 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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