Thursday, November 15, 2012

Sophia's Birthday

We recently celebrated our daughter's 2nd birthday.  For events I typically use a combination of a standard zoom (24-70 equivalent) and a telephoto zoom (70-200 equivalent).  On this occasion, her birthday was being held at a play center, which to me is a nice place but nothing distinctive from a photographic perspective.  Since the place wasn't of particular significance, and because it would have enough space for me to maneuver, I decided to use the Sigma 50 1.4 instead of the Nikon 24-70 on a Nikon D600.  For  telephoto, I used the Sigma 50-150 2.8 (non-OS) with the Nikon D90.  I used a flash with both cameras.

Here are a few shots from the party, and how I mixed ambient and flash.

The light levels were not too low, so I decided to make the ambient light dominant.  
ISO: With the D600, I used Auto ISO and allowed it to go as high as 12,800 ISO.  Although a higher ISO has more noise, using a high ISO has several benefits: first, it is easier to get enough ambient in the shot and the greater the proportion of ambient vs. flash in the shot, the more the shot looks natural to me.  Second, a higher ISO allows me to use a higher shutter speed.  When flash is the only thing that's lighting a scene, a high shutter speed is not necessary because the flash duration will freeze the action.  However, when ambient is dominant or when I'm mixing flash and ambient and the ambient is not completely gone, a high shutter speed helps increase the chance of a sharper shot (by minimizing camera shake and subject movement).  Third, a high ISO gives me greater latitude in deciding where to bounce the flash (I can choose to bounce from a far wall if needed).  Finally, a high ISO makes the flash work less, and recycle faster.
Shutter speed:  Because I knew the ISO would go as high as 12,800 ISO, I was able to choose a high shutter speed while still allowing ambient to be dominant.  I chose 1/200 (which is incidentally the sync speed), which is 2 stops above the 1/focal length rule (for camera shake) and fast enough for action shots of these kids (to minimize blur from subject movement).  I didn't want to go higher than sync speed because that would have reduced the power of the flash by at least 2 stops.

As with the D600, I decided the ambient would be dominant.  
Exposure mode: I shot in aperture priority and adjusted the exposure as needed using exposure compensation.  
ISO: I selected the highest ISO that I am comfortable with on the D90, which was 1600 ISO.
Shutter speed:  Like many DSLRs, the D90 allows me to specify the slowest shutter speed when using flash. I chose 1/60, which isn't fast at all, but would be ok for stationary shots.  I didn't want to select a higher shutter speed because doing so would have reduced the amount of ambient in the shot, making the light look more artificial.
Flash exposure compensation:  I reduced the flash exposure compensation as needed in order to achieve the exposure I wanted.  For most of the shots I reduced the FEC to around -0.7 FEC to -2.3 FEC because the flash was acting as fill, and I wanted the ambient to be dominant.

Here are some shots from the D90 and Sigma 50-150.  I found that the combination worked well in terms of focal length, but my D90 and Sigma 50-150 tended to backfocus.  I've noticed that my D90 and Nikon 24-70 also tends to backfocus, so I may have to send my D90 for adjustment (it doesn't have AF fine-tuning).

In post, I tweaked the exposures and adjusted the white balance.  I took the shots in raw and I could have completely neutralized the color temperature.  However, the actual light was quite yellowish, and I wanted to preserve some of that warmth, so I intentionally increased the color temperature slightly above neutral.

One issue I encountered was that on the D600, the reds tended to be exaggerated.  The tricky part was that in the shadows, the reds looked ok.  But with highlights or brighter midtones the reds looked wildly saturated.  
Default colors - reds too saturated
I first tried to reduce the red saturation in the HSL panel of Lightroom but found that the reds in the shadows and darker midtones suffered.  I tried adjusting the camera profile, and got a similar result.  
Brighter reds look better but darker reds such as the lips look too dark/purplish

In the end, what I did was to desaturate the images then increase the vibrance.  What vibrance does is to increase the 'saturation' but only of colors that are less saturated.  Vibrance also has a decreased effect on skin colors.

Here are some more shots from the party.

Blow the candle, Sophia!