I believe we have finally got to the point where users are moving from DSLR to Mirrorless camera in mass. The release of the recent Nikon Z9 and Canon R5/R3 has definitely shifter land photographers to mirrorless.
Underwater photographers have been lagging mostly because of optics compatibility more specifically lack of compatible fisheye options for mirrorless. Some classic lenses like the Tokina 10-17mm do not work properly when used through an adapter and releasing fisheye lenses has not been a priority for Canon or Nikon. The good news is that 1st party full frame lenses like the 8-15mm fisheye do work through an adapter and generally all DSLR optics 1st party can be adapted to a mirrorless camera of that brand.
I have sold my last DSLR in 2016 and generally never looked back. I believe this can be a harder move for a bird shooter or a sport photographer but the latest flagship cameras have performance for everyone.
EVF vs OVF
In terms of image quality there are no significant differences between a mirrorless camera and a DSLR camera. Improvements in image quality are mostly related to sensor improvements regardless of the system that runs that specific sensor. There are however some significant differences between an optical viewfinder and an electronic one.
An optical viewfinder literally means looking through the lens with your eyes, the primary benefit of an optical viewfinder is the lack of lag. Some people say that optical viewfinder have higher dynamic range but that is not actually correct as an optical device does not really have dynamic range limitation and neither is true that the human eye has 30 stops of dynamic range and all those fantasies.
The key problems of an optical viewfinder is that when is dark you cannot see things until your eye adapts and this happens slowly so most DSLR users switch to live view which essentially means using your DSLR camera as a mirrorless camera and watching a video stream on your LCD.
The other ergonomic difference is that you don’t know how your shot turned out until you review it after you shoot as the OVF can’t play back images being an optical device only.
An electronic viewfinder instead is nothing else than a micro LCD or OLED screen that is showing you a video of what is going on and is also able to playback the images.
This has the great benefit of not needing to take your eye off the viewfinder as the image is played back as soon as you shoot. The price to pay is a small lag between reality and what you see on your EVF.
While an OVF is real time an EVF has a lag that depends on how fast the sensor is being read. This can mean a delay of more than 30ms on very cheap cameras with just an LCD down to 5ms for the fastest reading Nikon Z9 and the likes. In general below 20ms is normally good enough for underwater use but for fast moving subjects like birds in flight less than 10ms is better.
The other benefit of an EVF is that in dark scenes it can boost the display so you can see better than your eyes in the dark.
Electronic Viewfinder Myths
One of the biggest myths about EVF is that they give you a what you see is what you get view of the image before you take it.
This is unfortunately untrue and it is important to understand why.
In a photograph we have two exposure settings the aperture and the exposure time. ISO maps the amplification of the system and is not an exposure setting however it can be useful to brighten an image that is too dark by amplifying electric signal after light has been converted into current by the sensor.
Normally a camera operates with the lens wide open and with a fixed exposure time determined by the sensor readout frame rate.
Imagine that your camera has an f/2.8 lens and the sensor is reading at 60 frames per second. You have set your underwater shot for f/11 1/250. However your camera will not close the aperture to f/11 until you press the shutter and it is actually operating at 1/60 exposure time.
In order to simulate the image the camera will try and adjust the brightness of the EVF to make it lighter or darker so that you can see properly what you need to shoot. This has actually nothing to do with the shot that will come out.
Some cameras Sony, Canon, Nikon and Panasonic have a preview or exposure simulation setting that will close the aperture to the value you chose and simulate the shutter speed chosen in the video displayed to your on screen and if you operate in full manual the display will actually change brightness as you change your exposure settings. However this does not actually show an image exactly identical to the one you will shoot because of the limitation on the exposure time. It will show something close to that image and only if you select the option to simulate the exposure. Some cameras are actually unable to perform a full simulation and the brightness of the EVF will not be adjusted and may give the impression the image is very bright when it is not.
If you shoot with flash of course all of this goes out of the window as the camera assumes the flash will always sort things out and the display won’t be affected unless you force it too but of course it won’t be any near to the image you will take. In essence you need to wait until after you have taken the image to see very much like a DSLR.
Are mirrorless better for the underwater photographer?
Despite beliefs of hard core DSLR fans mirrorless are a better option for the underwater photographer for a number of reasons:
- The EVF lag is no longer an issue as it used to be on old compact camera and the refresh is faster than your eye and brain can react to
- You can see the image preview without having to take the eye off the viewfinder
- If you need to shoot in ambient light you have exposure aids that will make sure your image is correctly exposed without trial and error
Is there a disbenefit to EVF? The EVD is a small screen and needs power to run this means that given the same battery capacity a mirrorless camera will have less autonomy however almost all decent cameras have over 300 shots autonomy and can get easily to 500+ so really there is no reason to hold back to DSLR.
In 2022 it is definitely time to move on.
If you are a DSLR shooter and see other disbenefit from a mirrorless camera leave a comment I want to hear from you.