Epson's new EVF--brave new world?

Started Oct 15, 2009 | Discussions thread
DrewE Senior Member • Posts: 2,053
Re: Epson's new EVF--brave new world?

Kuivaamo wrote:

An EVF would be a truly superior substitute for a high quality OVF, provided it has:

  • zero lag, even in very dim light (ok, maybe a smaller than 5 ms lag would be acceptable)

  • a refresh rate that is maintained above 60 Hz even in the lowest of light

5 ms lag necessarily implies a refresh rate faster than 200 Hz. Video lag is indeed a big disadvantage of many of the current EVFs, but 5ms lag is far too tight of a requirement, I suspect well beyond the capabilities of the human eye to ever detect.

  • a resolution that is above or very close to what the eye can resolve; ideally the resolution of the EVF would match the resolution of the sensor

Why should it match the sensor resolution if that's far beyond what the eye can ever resolve? (Most focusing screens likely do not come anywhere near having the resolution of the sensor, either--and even if they did, you'd never be able to see that much detail on them. Why require an EVF to vastly outperform an OVF?) That's not to say that the current reolutions are entirely adequate, of course.

  • a dynamic range that matches the eye's capability of examining a scene through an OVF, i.e. somewhere in the region of 15 stops?

I'd rather have a good idea of what the sensor is going to capture in terms of DR, so having an EVF that can display this is sufficient for me, even if it is compressed to have less contrast than it should. I suppose that could be a difference in personal taste (whether to see the image as captured or as it actually exists); but isn't the whole point of the SLR design with its mirror and all to present a viewfinder image that's as exactly like what will be captured as possible? If that were not so important and useful, why not use a far simpler system (like a rangefinder)?

Once these "minor" engineering problems have been solved, I'm sure most people who swear by OVF's now (myself included) would gladly make the switch to cameras with EVF's. Until then, OVF's do serve a very real purpose that simply cannot be substituted by electronic displays of any kind.

Also, once we have the technology to build the kind of EVF specified above, we'll have some truly awesome imaging sensors & processing: at least 30-40 mp (surely a lot more by the time such breakthroughs are imminent), 15 stops of DR even at high ISO, 60+ fps, and a quantum efficiency that is out of this world. But the flipside is that before we have these, we can't have a true EVF replacement for OVF's without making sacrifices.

EVFs do offer some advantages that OVFs cannot have, even if they don't measure up in all areas. A magnified view for manual focusing is one good example; the ability to show and/or overlay arbitrary shooting information is another one. (A live histogram, for instance, is very handy for getting an exposure correct.) For most people, a new technology doesn't necessarily have to exceed an old one in every possible regard to be an improvement. Digital pianos are, for many uses (but certainly not all!), replacing the traditional mechanical instruments not because they are superior in every regard--they aren't--but because there are enough advantages that outweigh the disadvantages. While I prefer playing on a grand piano (or attempting to play...), I would still haul the digital version to a (hypothetical) gig, as I can hoist it up by myself, fit it in my car, and don't have to get it tuned it when I arrive.
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--DrewE

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