Shooting Snow in HDR – Snow is HARD!
I have a line of Christmas Cards called The Lone Ornament. So when it snows inSouthern California…yes, it snows here…provided you go above 7,000 feet – I head up to the mountains to shoot for the next year’s card. So after it rain here on Thursday I knew there would be snow up there on Saturday.
So I headed up to the mountain hamlet of Idyllwild. It started to snow as I arrived and when I got to Humber State park it was a “Picture” perfect scene. About 6 inches of white puffy freshly fallen snow and it was snowing lightly as the sun played in and out of the clouds. I could not have asked for a better day…and I LOVE snow.
I got the shots I needed for my cards and they came out fantastic (no you can’t see them, they are a secret till December of 2012). When I was done I thought I would hike up the trail and try having some fun shooting in the woods and do some HDR after all, surely snow have a high dynamic range…or… we would think.
Measuring the DynamicRange
I hiked up the trail (Huffing and puffing, 7,000 feet is rough) and set up my tripod amongst some beautiful scenes and I set about to measure the dynamic range. I set my meter to spot metering. In snow spot metering is essential for measuring the dynamic range, using other modes the snow played too big a part in the metering and threw off any real measurement. Using Evaluative/matrix metering actually showed NO dynamic range as it metered everything the same.
At the time the sun was out and at f/16 and ISO 160, for the brightest spot on the snow I got a shutter speed of 1/500, for the deepest shadow area of tree bark I got a shutter speed of 1/20. OK that sounds good, so roughly 5 stops of range to cover.
But wait a minute. We have to remember one of the most important facts about in camera metering. In camera meters are reflective meters; they measure the reflected light off our subjects. And they are calibrated for middle gray. They will get the exposure correct if the object you are metering is middle gray (18%) or a midtone. If we measure white or black, the meter tries to make them gray. It will do that by underexposing white and overexposing black, both by about 2 stops.
So knowing that, that 1/500th shutter speed would underexposure our snow by about two stops. So really the exposure for the snow would be 1/125th. So now 1/125th to 1/25 is really closer to 3 stops difference in range, which tells us we really don’t need HDR!
But I pressed on and did some anyway.
What I found worked best was 3 exposures. And if I was using auto Exposure Bracketing it was best to also add in +1 Exposure Compensation to make up for the meter misreading the snow. Even though we know that snow will make the meter under expose by 2 stops, using +2 Exposure compensation was too much and our final bracket image was just too blown out. If I shot manual, I took the same compensation in mind and started my bracketing at 1/125 or 1/200
The other thing I found was spacing, if the sun was shining bright on the snow, + – 2 stops worked fine. If the sun was not shining brightly on the snow + – 1EV actually worked better. Yes that is NOT a broad range but again, this is not as dynamic a situation as we may think it is.
Here are three images I shot
Processing for snow
Shooting snow in HDR is just half the battle, processing it correctly is the send part. The problem most HDR processing programs have is handling white and especially large amounts of white. This has been my one pet peeve will all the developers. But it’s actually to be expected. Just like our meters want to make everything gray, that is also the function of the tone mapping of HDR programs. They will try to make everything a mid tone. This results in graying of all things white. So we need to take some steps to assure that doesn’t happen.
Regardless if you are using Photomatix Pro or Nik HDR Efex Pro or any HDR program what we have to watch is how much compression we apply. In Photomatix this is Strength and Lighting adjustments. In HDR Efex Pro it is Tone Compression.
If we were processing in Photomatix we would want our Lighting adjustments to be Natural + and a strength of under 50. In Nik HDR Efex Pro, which I used here, I used Tone Compression. set to 0.
That still leaves us with some pretty dingy whites so we need to make an adjustment to our white levels and quite a bit of it to, I used between 20 and 40% more white levels to get the images right, you want the brightest parts of the snow just below blowing out. I also added about 12% blacks to bring back a little shadow detail and then about 20% to the structure. My fine adjustment just to bring out a bit more detail I upped the method strength to 20% with the Neutral method.
This gave me the most pleasing look to the image, the cool part was I needed no further post processing for any of the images in Photoshop or Lightroom.
Now comparing it to a single image shot with the correct exposure, you really won’t see a huge difference. In fact I think you could work with a single image and get similar results. We don’t really see a big difference in range because quite frankly, there isn’t much anyway. But there is an improvement in detail that I feel may be worth it. Would I shoot snow in HDR again? Maybe, but I am not sure it was worth the effort completely.
Perhaps since it was such a beautiful day in the wood and snow, I should have forsaken the tripod and all the set-up and time it took and just enjoyed the hike more and shot conventionally…but then again…I DO run The HDR Image…soooo
Hope that helps,
Final note to self, make sure you waterproof hiking boots, subset note to self, be thankful that wool socks keep you warm even when wet.