2010 - Week 20, Minimum Focusing Distance

Living Room Couch - light source south facing windows
Mary 24, 2010 5:36 pm
Nikon D90, 50mm 1.8 - shot in RAW
Manual, No Flash, ISO 640, SS 1/50, f/3.2
AF-S, Pattern Metering, WB set to A6 (warm)

Minimum Focusing Distance is probably pretty straight forward for most photographers, but for the amateurs like myself its good practice to know what the minimum focusing distance is for all your lenses.

My 35mm f/1.8 can focus as close as 12", my 50mm f/1.8 can focus as close as 18" and my 18-105mm f/3.5-5.6 VR also focuses at close as 18".

Looking at those values one might assume that to get the best closeup I should use the 35mm because I can move 6" closer to my subject, but since it is also 15mm wider, I really don't gain anything because I "see" more of the subject with the wider lens. At 18" and 105mm I could be really close, but I would also be at f/5.6 which may not give me the shallow Depth of Field (DOF) that I would like to see on such a close up shot.

There is a really neat calculator called the DOF Master (link over on the right) and its good to plug in a few different focal lengths, distances and f-stops to see how much DOF you really have to play with.

For these shots, since I was going to be SO close, I knew I could not shoot wide open (f/1.8) or their eye might be in focus, but not their nose or maybe only one eye. I wanted most of their face to be in focus, and you can see how quickly the focus falls off by the time it gets to their ears.

My next consideration was shutter speed. The rule of thumb for children is to never go less that 1/125th, but since they were sleeping I didn't to worry about movement, so I was safe to go as low as the reciprocal rule or 1/focal length - in this case 1/50 of a second.

So what I had to tweak to get proper exposure was the ISO - which had to get bumped all the way up to 640, which sometimes gives me noise, but with a proper exposure I don't see any in these photos.

How did I get my subjects to "pose"? Well, they didn't get a nap at school because of swimming lessons and then they each worked extra hard during lessons trying to master the roll to your back to take a breath technique since one of them gave me quite the "almost" drowning scare before lessons even started. So we all laid down together on the couch to watch the Disney Planning DVD and it was so exciting we all fell asleep.

I set my focus point to the top set of eyelashes - the girls have amazing thick, dark eyelashes, not so long or curly, but dark and thick. I limited my post processing to fixing only a slight color cast in their hair, because I wasn't going for a perfectly posed portrait, I just wanted to capture them exactly as they looked there on the couch, which is why I manually adjusted the white balance on camera instead of tweaking in Adobe Camera Raw.





post-processing
In Adobe Camera Raw under the HSL/Grayscale tab, slide the Green Hue slider almost all the way to the left to remove a greenish hue they get in their hair swimming in salt water pools. It was the first time I had attempted this type of adjustment, so it was a pleasant surprise when it actually worked! No further adjustments were made in Photoshop - I'm sure I could have massaged a few of the shadows/highlights on their faces, but it didn't feel right in this instance.