Sunday, January 26, 2014

Depth of Field in a Marco World

When shooting macro shots with a DSLR camera the depth of field or DOF can be extremely small.  The DOF is the distance between the nearest and farthest objects in a scene that appear sharp in an image.  

The DOF is influenced by several factors
  • The closer the object in focus the smaller the DOF gets.
  • The longer the focal length of the lens the small the DOF.
  • The wider the aperture (smaller f-stop numbers) the smaller the DOF.
  • The bigger the camera digital sensor the smaller the DOF.
To illustrate the impact of the aperture on the DOF I took the following series of photos keeping everything constant, except the aperture.  I was using a Canon 5D Mark ii (full frame sensor), 100mm macro lens, focused about 6 inches from the water drops.  Of course, the camera was on a tripod to eliminate any movement.

You can click on any of these photos to get a larger view and then flip though them using the right and left arrow keys.






You can see that even at a small f/22 aperture the depth of field is only about 2 inches.  At f/2.8 it is about the width of one small waterdrop.   Here's a crop of the f/2.8 shot where you can see just how small the DOF is.
f/2.8 cropped
Understanding the DOF is important in all photography and critical in macro photography.  In order to control the DOF you need to understand the factors that influence it and adjust those to create the composition you want.  Choose the camera and lens combination that will get you in the range you want then adjust your aperture and distance to get that really cool macro.

Saturday, January 18, 2014

Fooling Your Camera's Auto White Balance

All light has color characteristics.  Our eyes and brain have been created to discern and adjust for most color differences, which we never notice.  However, the sensor and high powered computer in our digital cameras are not as smart as we are and can be fooled.

The color of light is expressed as a temperature in degrees Kelvin.  Sometimes it's warm, like the sunlight at sunrise.  Other times it's cool like the sunlight on a cloudy day.  Artificial light also has color.   Florescent  bulbs have a cool blue tint while tungsten incandescent bulbs have a warm yellow tint.

Your digital camera has a feature called Auto White Balance (AWB) that tries to measure and adjust for these differences in light color so things that appear white to your eye are white in your photo.   Modern cameras do an amazing job and get this right most of the time, however they can be fooled.

If a scene is dominated by one color the auto white balance function can be fooled into assuming that the light has a lot of that color in it. This can result in an incorrect white balance and an undesirable color cast in your photo. The two photos below show one case where the camera was fooled.

Auto White Balance

Daylight White Balance

About 3/4 of this photo is dominated by a strong yellow color from the field of Canola (Rapeseed).   In auto white balance mode the camera senses all this yellow and thinks the color temperature of the light is warmer than it really is.   The camera makes an automatic adjustment (the auto port of AWB) to make the photo cooler.  As a result, the photographer's skin has a sickly blue color.

In fact, the photo was taken on a bright sunny day around mid-day and the light was cooler (bluer) than the camera thought.  In the second photo I changed the white balance from auto to Daylight.  If you compare the two photos you can see that the photographer's skin tone in the second photo is much more natural.

So, when do you rely on Auto White Balance and when do you go to manual white balance?  Here's what I do.  Most of the time I don't care about the white balance setting on my camera because I almost always take my photos in RAW format rather than JPEG.  JPEG format has the camera's color adjustments applied, but RAW does not.  With a RAW file I can correct the white balance when editing the photos on my computer.  In fact, this is how I created the two example photos.  I was able to change the white balance setting on the RAW file to create the two different versions.  When shooting in JPEG mode it is very difficult to correct the white balance once the photo is taken.

When shooting in JPEG mode I will be aware of the color cast of the photo I'm about to take and decide if I need to override the Auto White Balance.   As I said, most cameras do a pretty good job on auto mode so this doesn't happen often.

Devices such as Expo Discs can be used to determine the color temperature of the light and creating custom white balance settings.  This is a more advanced topic that may get covered in a future post.

Sunday, January 12, 2014

There's Bad and Good Light?

I'm preparing to teach a basic photography class.  This is a first for me and I'm trying to put some effort into preparing.   In the very first class I'm going to touch on light and how there can be good light and bad. 

Light in itself is not good or bad and it can not create a good photograph, but depending on the characteristics of the light it can make our photographs better or worse.   I've gone through my photo library and have picked out a few photos to show how light can change a photo.   Here's one example I came up with.

Both shots are the same creek taken from the same spot using all the same equipment.  The difference is the time of day and the direction of the sunlight.

Morning Shot
The morning was a bright sunny day and that sun was shining down on the little cascade.  The bright clear sunlight made the scene very contrasty.  The brights were too bright and blown out (no details in the brightest parts).  I could have compensated for that bright light by turning down my exposure but then the shadows would be dark and there would be little details to be seen there either.   Typically I'll walk right by a scene like this but that little cascade was just too pretty to pass up.  I was hoping I could do something with it in post-processing.

Afternoon Shot
Lucky for me we came back by this same spot in the late afternoon and the light conditions had changed dramatically.  Now there was only soft indirect light illuminating the scene.  No harsh , shadows to deal with.  The soft light also created less glare on the water, rocks and foliage. 

One reason I'm talking about light in the very first class is it is the single most important part to photography.   When shooting landscapes and nature you have to take the light God gives you and either work with it or pass.  There is no amount of camera gear or post-processing editing that would make the first shot look like the second. 

Understanding light is foundational.   Everything else is secondary.

Monday, January 6, 2014

Planning For a Disaster

There are natural disasters occurring around the globe all the time.  Just last year there were floods in Colorado, fires in California, a mega typhoon in the Philippines and 760 confirmed tornadoes in the US.   These events can wipe away in an instant what we have worked for years to build.  Many times people are able to prepare and there is not a great loss of life, but that's not always true about property.

Recently a family in our neighborhood lost their home to a house fire that from the outside appears to have consumed pretty much everything in their home.   The good news is they all go out safely.  This is the fifth home to burn in our little neighborhood since we moved in about 32 years ago.

Mt. Cammerer Firetower
This house fire got me thinking.  What if that happened to us?  Most of our material possessions would be replaced by insurance but somethings can not be replaced.   There are some steps that can be taken to prepare for a house fire and avoid people being injured, however there is not much we can do to protect things in our home, particularly those things we use and don't want locked up somewhere.    I also got to thinking about the tens of thousands of photos I have on my home computer.

Right now I have 3.4 terabytes of system and data disks, plus  3.2 terabytes of backup disks.  Every night my system makes backup copies of my files.  When (not if) I have a hard drive crash I can buy a new one and put all my files back.  Because all these disks are in the same physical place a house fire or a waterline break in the kitchen above my computer could destroy the original files and all the backups.  All gone.

I decided to find a way to save my photos should a disaster occur at home.  I checked out out a couple online backup services to backup my files to "the cloud" on the internet.  In theory, if my PC is destroyed I can eventually replace it and restore all my important files to the new computer. I loaded a 30 day evaluation copy of one of the leading services and found it was going to take a month to back up what I had on my hard drives! With the number of images I load to my PC after a big trip this system could take days to catch up.

I have decided to give up on the cloud backup until my internet service provider offers better upload speeds.  Instead I purchased a portable hard drive that can be attached to my PC via a USB 3.0 port.  I then back up my pictures, documents, music and other important files to this disk and store it in my office at work.   A low tech but low cost solution.   The key is to be disciplined to bring the disk home periodically and make a new backup.

I'm going to keep doing my backups on my computer in addition to the offsite backup.   Nothing wrong with doing both.

What do you do to protect your important files?

Wednesday, January 1, 2014

The Calendar Chronicles - January 2014

It's here!  2014 has arrived.   I hope you have started the year off right and that you are blessed in 2014.

It's also time to share a little about the photo for January - Second Beach, Washington State.  If you're like me, you're thinking that is not a very creative name for a beach.  One of three beaches (yes First Second and Third Beach) just south of the village of La Push Washington.  Like the other two, Second Beach is hemmed in by dramatic bluffs and headlands. To get to Second Beach you have to hike 2/3 of a mile up and then back down a forested trail.  It was a bit confusing at first because we started out above the beach and hiked up.   After a while we made our way down to the beach.
Path to Second Beach

We were there as part of a photography workshop with Bill Fortney and  His Light Workshops.   There was at least one other photography group there that afternoon so there were plenty of photographers wandering around the beach.      We arrived at the beach at 8 PM and stayed about an hour while the sun was going down.  It sure is nice photographing sunsets on west coast beaches than sunrises on the east coast beaches.

I took 60 shots in those 60 minutes on the beach, which is less than what I usually take.  There was a lot of time waiting for something to happen, the light to change, people to move, or new ideas to pop into my head.

Sea Stack and Sea Gulls

I was fascinated by the sea stacks offshore.  We don't have anything like these where I grew up.   These forbidding landmarks are part of the Quillayute Needles National Wildlife Refuge. Inhospitable to humans, they're productive breeding grounds to thousands of seabirds, oystercatchers, murres, gulls, petrels, cormorants, and auklets among them.

You never know what you will get at sunrise or sunset.  This time we were blessed with beautiful clouds and a break in the clouds that allowed the sun to shine up and light up the under sides.  As the sun set I positioned myself at this cool rock surrounded by a pool of sea water.  I could see that the sun was going to set directly behind the headland to the right of the primary sea stack and might shine through the natural arch.  Now it was just a matter of getting ready and waiting.  I was rewarded with warm colors from the sunset and blue of the darkening skies for some nice color contrast.  The rock and reflections in the pool made interesting foreground for my photo.

For the photographers that might be interested, this was shot at a 32 mm focal length using a 24-105 mm lens with a small f/22 aperture.  The wide lens and small aperture allowed me to have the foreground rock and the trees in the distance all in focus.  This was a one second exposure so I was using my tripod.  I set the camera down low to the ground to be able to include the sand, rock and clouds.

I hope you enjoy this photo during January and it reminds you that His greatness can be seen through His creations all around us.