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Wednesday, 11 September 2013

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As Arthur C. Clarke said, "Any sufficiently advanced technology is indistinguishable from magic" and there's the old maintenance advice, "if it's working don't faff with it" : ]

Mike, have you read The Big House by George Howe Colt? It's an enjoyable read about an East Coast family who has to sell their summer home. I found myself sharing their nostalgia for the house, even though I've never seen it, let alone set foot in it.

My impression is that one of the biggest gains of the m240 over the m9, and the x100s over the x100, is in this area (for both of them.)
I don't know how either compare to the Rx1, but in my shooting both seem better than their predecessors.

I do not know what really is going on, but these beasts recognize faces, so I am not surprised that they recognize a picture with the sun in it. So I guess it is just software, or as you call it, magic.

Mike, that cropped image weighs in a 532kb, and takes a noticeable amount of time to load and render. Just fyi, if you are having traffic spikes - anyone loading the main page loads that image.

Will

Multi-segment (or matrix to use Nikon's trademarked term) has got a lot smarter over the years. It works well when it works (and then some small fraction of the time gets confused).

All of the multi-segment metering algorithms use luminance data from the whole frame plus color data plus the distribution of both in the scene to try to figure out what's getting the metering right for this scene.

This is rather than just assuming "Pick an exposure that makes the whole thing mid-tone gray on average". I suspect is your mental metering algorithm roughly based on center-weighed systems of the past. The downside of multi-segment is it can be an unknowable black box.

For example, check out how your multi-segment metering system meters off your hand in the bright sun (get it to cover a chunk but not all of the frame). If you stick a gray card there you'll get the same exposure. Most systems realize that they're metering from skin in the center of frame and not from gray card and compensate for that +1 EV exposure compensation that caucasian skin needs. Often they even manage to determine the correct offset for different skin types.

This can be handy in street photography in bright sun: use multi-segment metering with manual exposure. Meter off your hand in sunlight (or in shade) to set the exposure for shots in sunlight (or in the shade). Look at "Gustavo Minas" street photography in London 2013 on Flickr to see multi-segment metering with manual exposure in action.

http://www.flickr.com/photos/gustavominas/sets/72157633419332487/

Regardless of your photographic style multi-segment metering with manual exposure can be a useful trick in constant light especially with a histogram or blinkies to help set the highlights. Some might find this anathema but the technology in those newfangled cameras can help even skilled old time photographers.

I've always avoided having the sun in frame for very long or at all, even if just setting up a shot, if using a mirrorless camera. I just feel like direct, focused sunlight shouldn't strike an exposed sensor for any meaningful length of time. It might just be paranoia on my part, but with dSLRs, I at least knew that it was an optical path until I pressed the shutter. With my Fuji I'm more worried about some form of sensor burn(-in).

Will

I also note with some amusement that one of the latest iPhone 5 sample shots is a "straight into the sun with something in the foreground" shot which is exposed nicely for the forward scatter from grass in the foreground.

I don't know how many times they took that shot (!) but I suspect this "correct metering with large highlight in frame" was a feature they tweaked in the iPhone 5 camera software (or camera module - it isn't clear who made it).

e.g. see it here http://www.steves-digicams.com/assets_c/2013/09/iPhone_5S_photo-21140.html

Even good cellphone cams can do good multi-segement metering (they need to do it more than anyone else!).

Don't worry (too much) about sensor damage when shooting into the sun. The IR filter in front of the sensor should cope with that for "normal" intermittent use.

For those that don't know: SLRs and DSLRs use a seperate full frame RGB metering sensor to do the same sort of thing a mirrorless/compact camera use the main sensor for.

With all due respect to the technical explanations above, I like the Arthur C. Clarke view. It is magic!

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