A quick word on 'snowfall' photographs

(Alternate Title: "A foot of snow later...")

Thanks to it being an El Nino winter, there's been quite a bit of wintery mix precipitation that's been hitting the Northeastern USA this past month.

As such, there's the temptation to go take a digital photo that you're going to email to family & friends (probably to get some sympathy for snow shoveling).

So you go out and take a photo during the storm ... and all that nice white snow turns out a yucky dark grey in the photo - - that's probably not what you wanted, so why did this happen?

The short answer is "technology", specifically, your camera's automatic exposure system.

Yes, we've become quite accustomed to auto-everything cameras, but a downside of this is that the camera never knows what you're photographing, so it guesses.

Simplistically, this "guess" is known as 18% grey, and while it works great 90% of the time for us, where it doesn't work so well is when we have a low contrast scene - - and during a heavy snowfall is a low contrast scene.

With a low contrast scene, the camara's educated guesses often goes wrong: it is looking for "dark AND grey AND bright" contrasts, but it can't find what's not there.

So while a white cow in a snowstorm (light on light) or a black cat in a coal mine (dark on dark) are both intuitively obvious to us, for the camera, it sees both as low contrast and hard to figure out. Subsequently, it can get the overall exposure settings wrong.

Typically, the camera's bad guess is that the cow/snow is "too bright" of an overall scene (it can't find true black), so it sets for a short exposure, which turns white into grey (underexposed). Similarly, the cat/coal is interpreted as "too dark" (can't find bright white), so it calls for a long exposure...and this turns black into grey (overexposed).

Here's an example of an image that's was a low contrast light scene, so it was auto-exposed to be a bad "grey" shot (underexposed), which was corrected later in post-processing:


The trick to avoid this problem is pretty simple: be aware of how your 'automatic' camera settings work, and anticipate what it will do based upon what you know is in the picture. The simple rule of thumb to remember is that the camera will want to turn everything grey if the scene lacks a good cue (bright sunny sky for contrast) to help it out.

With digital, its pretty easy to take a test shot and then adjust your settings. And if you forget (or not bother), you can fix the incorrect exposures later in post-processing. Its up to you to decide how much its worth a little bit more effort upfront when taking the picture, both to get better overall results, as well as to save time later from less post-processing.


And of course, if you do choose to override the default exposure while taking the photo to get what you want, do also make sure to remember to set your override settings back to normal afterwords.


-hh

Winter Traction: Snow tires versus 4WD - which is better?

Many years ago (turns out to be 1999), Car and Driver magazine did a comparison test for winter driving, where they asked the question of if you could only have one or the other ... snow tires -OR- four wheel drive ... which would be more beneficial?

Obviously, having both 4WD and snow tires is the best combination, but the intent here was to ask which provided more of the benefits, since neither one is free.

By supreme providence, I happened to rediscovered this 1999 article. It is linked above (and again here).


Its a nice read, but I know that we all want a shorter summary.

Here's Car&Driver's tests summary:

Hill-Climbing Traction: 4WD
Straight-Line Acceleration Performance: 4WD
Braking: Snow Tires
Handling/Lateral Acceleration: Snow Tires
Handling/Slalom: Snow Tires

And C&D's conclusion:

Four-wheel drive helps get cars going. When it comes time to brake or change direction on low-traction surfaces, the extra mass of the driveline becomes more of a detriment. Folks who live in hilly places that get snow may need the climbing capability of four-wheel drive...Almost everyone else will most likely be better served by using winter tires. Acceleration takes longer, but in an emergency, the handling behavior and improved lateral grip of two-wheel drive and winter tires -- in the slippery stuff -- are the safer bets.


In other words, snows before 4WD.

If you need a catchy sound-byte, try:

With 4WD, you may have 4 wheel 'go', but everyone has 4 wheel 'stop'.

The general reprocussions are that 4WD without snows will get you moving...but into trouble from which your tires aren't adequate to save you from. Snows without 4WD might not let you get moving as easily, but you'll have better roadhandling and shorter stops, which means more likely to get home safely.

Its winter again in the Northeast USA, so let's all be careful out there.


-hh

Cayman Brac after Hurricane Paloma

In November 2008, the 71st anniversary of the great Storm of 1932 was noted to nearly the same exact day with Hurricane Palmoa hitting the island as a Category 4 storm.

With modern technology, there's photos online that document the damage this time. Here's three such slide shows:

http://www.blueoceanart.com/hurricanepaloma/index2.php

http://www.caymannetnews.com/palomabrac/index.html

http://www.caymannetnews.com/palomabrac/part2.html


Amongst others, the Rotary Clubs of Grand Cayman is accepting donations to help those in need. Their website is:

http://caymanrotary.wordpress.com/


We also understand that Robert Walton is working to help conserve the endangered Cayman Brac Parrot, as its habitat and food sources have obviously also been severely impacted by this storm.


-hh

A busy fall...

The last few months have been quite busy, with a bit of globe-hopping. Within the past three months, I think there were 3 weeks in Europe, 2 weeks in the Caribbean, 2 weeks in Africa and a quick trip from the East to the West Coast to present a paper and vamoose back home.

Thus, there's the latest batch of travel photographs organized and sorted while getting ready for winter to hit us locally. In taking a break from that project (1000 down, 2000 to go), the subject of travel while exploring found an interesting website utility, namely the ability to make up personal "Been There" travel maps from Phillips 66.

Domestically:



Internationally:



If you're looking for changes since 2007, well, there's just Denmark.
In the meantime, there's still plenty of things on the "1000 Places before you Die" list that remain to be worked on.

And since it is that time of year for one's annual holiday contribution to Capitalism, it is quite obviously way behind schedule as a result of not really being at home for half of the time over the past few months. Plus there's more important things. Just last night, we spent a solid hour on an expensive long distance phone call to a friend who survived having half of their house fall on top of them from a Category 4 Hurricane a few weeks ago. The gift wasn't really our offers to send Care packages, but simply the opportunity for a listening ear for them to be able to give that big emotional 'dump'. Nevertheless, we'll be putting together a package for them over the next week or so with some surprises, since they have months of clean-up and recovery to do.


-hh