I was fortunate enough to have help from Bryan Mayo, owner of MP&E Dallas, and his staff, who provided the Alexa and a couple of Cooke S4i lenses, and Ted Barnett, owner of Lone Wolf Media, who provided the Sony F55. I also had fantastic help from the talented actors at Linda McAlister Talent Agency who came out to the test shoot to be on camera.
I wanted to set up three lighting scenarios. The first one is a high contrast scene with very little fill light, only a bounce card.
This was to see how much noise in the shadows was present and also see some example of dynamic range in a high contrast ratio situation. I used a tungsten Kino Diva for a key and a mostly daylight balanced (3 tubes 5500k, 1 tube 3200k) Diva kicker and then balanced the cameras to 3200k. Both cameras shot in Log mode. Log-C for the Alexa and SLog-2 for the F55. I didn't care about matching exact T-stop because I would have needed a handful of ND filters for Alexa, since it doesn't have roll-in ND on the camera the way the F55 does. So you will see a wider depth of field with the Alexa in the first scene.
We also shot the scenes with S-log-3 but noticed considerable noise with this relatively new log from Sony, so I am not sharing that result here. I wanted to see the optimum quality result of each camera.
The second scene was a closer key/fill ratio but with the same two sources in place. Also brighter background. It was interesting to see where colors stayed the same and where they did not. Notice the difference in the intensity of the blue kicker on the F55 in both scenes 1 and 2.
Because my client's post house prefers to work with ProRes files, I sent the F55 image to a Ki Pro Mini via the SDI cable with no LUT, so the Sony F55 ProRes had the same SLog-2 attributes applied. I was recording ProRes 422 in the Ki Pro, and ProRes 422HQ in the Alexa. Captured a higher data rate than the F55's native XAVC codec, which I believe was around 80 mbps at 23.976.
Part of my test was to color correct using basic native plug-ins in Premiere Pro CS6. Certainly superior results could be achieved using DaVinci Resolve or even Speedgrade, but part of my client's concern for the F55 was that it might require expensive color grading time to achieve Alexa level imagery. I think it's good to know if log footage can be corrected with basic native plug-ins for speed and reduced post expense. So these stills were grabbed from color corrected video within Premiere Pro CC, but then for optimum results I used Speedgrade to grade the final video that plays on YouTube. The link is at the bottom of this blog.
The third scene was the only exterior. I chose to shoot this in the shade of the MP&E building near the end of the day. This meant the shade was probably more around 7000K or higher, much cooler than the 5600K preset white balance limit of both cameras in Log mode. So seeing how well the footage was brought back toward warm became part of the test.
As with log files, color correction was mostly a matter of increasing contrast, and except for the exterior, I didn't want to influence the natural color. Within Premiere and Speedgrade I had to use some Color Balance on the exterior shots to shift the image off the cooler cast the shade created. My aim was to match the cameras in contrast and saturation without changing the sensor's natural rendering of skin. And it's worth mentioning that I used an HP Dream Color monitor in Rec.709 mode to achieve a grade that would more closely meet broadcast standards. What you might see on your monitor may vary.
In Conclusion: I was rather pleased to see the F55 hold it's own. Using the exact same lens and lighting situation really showed me that the F55 can have a comparable image to the Alexa under favorable lighting conditions. Both cameras show off their dynamic range with the edge leaning slightly toward the Alexa. For instance, I could see easier into the fill side of the first scene. And the Alexa was more gentle, recording the 5000K kicker than the F55. In fact I feel the F55 tends to grab hold of a skin tone and then exaggerate it so faces tend to get spotchy in places compared to the smoother overall skin rendering from the Alexa.
The Alexa leaned consistently toward a yellowish hue but was slightly less noisy in the shadows. Of course, I've left some quality on the table with both cameras. I could have shot ProRes 444 HQ with the Alexa and SR444 with the F55. The SR being more limitedly accepted in NLEs at the moment, gives the edge to Alexa, but there are always trade-offs.
There is great value in the Sony F55. It is quite capable of producing a nice image and has lots of "look" flexibility. 4K capable, global shutter, s-gamut, multiple codec options, more lens options, lighter, less power hungry and best of all, much less expensive to own, rent, or insure. But in the end the Alexa still produced the best, more cinematic image, which is my preference all the time. So I still had to put my money down on the up-coming Amira (the baby Alexa) which I hope to take delivery by September 2014.
Here's the link to the YouTube video of the camera test: https://www.youtube.com/watch?v=rQM1WPyQ60o&feature=youtu.be
Feel free to leave your thoughts. Thanks for your interest.