“Optical viewfinder” is defined here as one which allows focusing*.
My recent experience with the Leica M Typ 240 clarified one thing for me:
These are not redundant— each serves a useful purpose that the others do not.
The new Leica M Typ 240 is the only camera on the market that has all three: optical viewfinder with rangefinder focusing, EVF, rear LCD. But it falls short of being ideal: zooming to focus is restricted to the center of the image only. The Fuji also qualifies because its optical viewfinder allows autofocus operation (but no facility for manual rangefinder style focus).
- Most compact cameras have a rear LCD, but no EVF and no optical viewfinder.
- Some compact cameras have a rear LCD + EVF, but still lack an optical viewfinder.
- DSLRs have a rear LCD and optical viewfinder, but no EVF.
I hope to see DSLRs designed to support an EVF appear on the market in 2013. For smaller cameras one will have to compromise with EVF + LCD, which is fine for those smaller form factors. What is weak is the LCD-only camera design.
To be clear, the connector supporting an EVF ought to support an EVF or larger LCD or any such device; an EVF is only one of many possible options.
* Hot-shoe mounted optical viewfinders are very expensive for good optics, crude for composing, make it guesswork to place the AF sensor precisely, TOTALLY useless for manual focus, and are without parallax correction or diopter correction or any display of settings of framing guides or similar.
Composing and focusing
Ideally, a camera should have three distinct ways of composing and focusing:
- An optical viewfinder that supports focusing.
- An electronic viewfinder (EVF) for composition and zoomed-in focusing.
- A high-resolution rear LCD. Useful for composing and focusing, but generally requires the use of a high quality loupe for reasons of glare and presbyopia.
Let’s take each of these in turn.
A rear LCD is a poor choice in several cases:
- Glare makes it hard to see in many conditions.
- Presbyopia makes it difficult to see any details, hence it requires use of a focusing loupe for any kind of manual focus, but even for seeing the autofocus position or even the settings.
- Camera shake from holding the camera at arm’s length means that anything under 1/125 sec is a hit-or-miss risk.
In practice, a rear LCD (only) severely degrades the viability of a camera for all around shooting, and lowers the success rate, particularly in dim light.
Allows mass-coupling the camera to the head/body, making lower shutter speeds a far more viable option than holding the camera at arm’s length.
- Often no power required, or very little power.
- With DSLRs, maintains the 3D perspective of the eye.
- Maintains the native contrast of the scene (eye can see into highlights or dark areas just as it can normally).
There are drawbacks to an optical viewfinder:
- Generally makes the camera larger and more costly.
- Mirror slap from flipping up the mirror, along with brief blackout.
- Modern focusing screens are for autofocus and brightness, and generally quite poor for manual focus, so that use of manual focus lenses can be hit or miss on accuracy. Well, mainly 'miss' for high performance fast lenses. For example, the Nikon D800E demands high focus precision, yet has a focusing screen which is terrible for manual focus.
- The optical viewfinder is a separate optical path and it is almost a certainty that the length of this optical path differs from the length of the optical path to the sensor. So that even with perfect 20/20 vision and a good focusing screen, focus might still be off.
- Precise composition suffers with cameras having less than 100% view, and many cropped-sensor DSLRs have a seriously unpleasant “porthole” effect which I find degrades my ability to compose; I see the scene differently with such cameras, one reason I avoid them like the plague.
Like an optical viewfinder, allows mass-coupling the camera to the head/body, making lower shutter speeds a far more viable option than holding the camera at arm’s length.
An EVF has many positive qualities.
- Eliminates glare.
- Addresses the presbyopia issue.
- Generally shows 100% of the composition.
- Can show shooting information, virtual horizon, gridlines, etc.
- Allows zooming to 10X or similar for precise focus on the sensor itself.
- The focusing screen on high-res DSLRs is incompatible with accurate focus by eye for fast high performance lenses. This is a screen issue, not an eye issue. An EVF with push-button zoom is a critical Live View feature.
- Generally capable of showing an exposure preview.
- Flattens the image to 2D, just as with a ground glass does.
Still, while EVFs are getting better and better, none as yet lifelike; all suffer in varying degrees from contrast limitations, blowout of bright details or pure-black shadows or simply too-low resolution. Hence having an EVF an an optical viewfinder is very helpful in some lighting conditions.
Also some camera implementations are half-baked affairs: done right, one can zoom in and scroll around freely. Leica won’t allow any zooming at all, Sigma DP Merrill and Fuji are modal (choose a focus point, zoom in, but zoom back out if one wants a different focus point!). Who thinks this stuff up?
A bit more
A camera with only a rear LCD forces the camera to be held away from the body.
Held with arms extended, the success rate for sharp images plummets at 1/125 second and lower (varies depending on focal length). But mass-coupled to the body with a viewfinder, the odds rise by at least 2 to 4 shutter speeds.
With my Nikon D800 or similar DSLR, I can generally make a sharp image as low as 1/8 second with proper technique and several attempts. And I have a fairly high success rate at 1/30. By success, I mean for truly sharp images, not sort-of-sharp almost usable images.
With a camera like the Sony RX1 (without its optional EVF), I found that anything 1/100 or slower comes with poor odds— holding the camera out at arm’s length is a recipe for blur.
A camera with a rear LCD (only) is literally a blur for some users.
An EVF with a diopter adjustment also mitigates having less than 20/20 vision.
As we age, our eyes lose their flexibility, pushing the close-focus distance out farther an farther:
- A child can focus on its own nose or thereabouts and in very dim light too.
- In my late 40's, I can focus no closer than about 30cm under dim lighting, somewhat better under bright lighting (depth of field from pupils). I have contact lenses for vision correction to 20/20, but this moves out my focus distance.
- Someone in their 60's or 70's might be effectively at infinity for eye focusing, making it impossible to ever see the rear LCD clearly without reading glasses.
Correcting for near-sightedness move the focus distance out as is my situation. Glasses might be used for some, but this does not address glare or camera shake.
A rear LCD suffers from glare.
Even when immaculate there is glare. With a little finger grease, sunblock, sweat or similar on the rear LCD, the glare can become a real impediment.