posted on Nov 23, 2009 at 7:25PM
Head-2-Head Lighting Review: Profoto Pro-8a 2400 Air vs. Broncolor Scoro A4S
Color & Exposure ConsistencyBy Ted Dillard
The final piece of the puzzle is the accuracy and consistency of color and exposure, from flash to flash, but also from head to head and from channel to channel. In an ideal world we’d like every system to be perfectly balanced for 5500K, daylight, and we’d like every exposure to be exactly that. Our expectations here are very high, considering the price and claims of these two systems, and the evaluations are concentrating on real-world results, that is, what you’re going to see when you shoot.
The first session was simply concerned with color and exposure consistency from shot to shot from a range of full power to minimum power. We shot a series of pops at full, half and minimum, and compared the exposures within each series. We then compared color and exposure from head to head, and from channel to channel. To give us a baseline color balance, we used Adobe Camera RAW to set the white balance of all the exposures to 5500K, allowing us to evaluate both how far off the systems are from that point and how much they differ between shooting modes.
That piece of the story is probably the most interesting from the start. Here are shots of the ColorChecker from the two systems, and in the case of the Broncolor, with both Color Controls on and off. It’s not pretty. For the price of these systems, we’d expect to see temperatures a lot closer to 5500K.
The first sample below is the Profoto, and it’s running a color temperature of around 4650K. The second sample is the Broncolor, running at minimum also, but with the Color Control turned on. It also is a little off, but close, at around 4600K. The last shot is the Broncolor system with the Color Control system de-activated, to allow the absolute minimum duration. It’s pretty cool, at around 5850K.
Even without Color Management, in your web browser, the differences are visible. Although all of the files are able to be corrected to neutral using ACR, the way that colors are mapped from the original captures is very much dependent on the spectrum of the light source. That is to say, if your light source is skewed to one end of the spectrum or another, it will affect how the colors get plotted to the full spectrum. Again, this is not a particularly bad result, it’s more that we have high expectations from systems at this level.
Here’s what the Imatest plots look like, comparing the Broncolor with CC on, and then off.
The color and exposure consistency from flash to flash, head to head and channel to channel gives us some fairly remarkable results, but does not give us much to observe. The most impressive results are from the Broncolor system at full and half-power, giving measurements that are only points off from shot to shot. Here are the worst results, measured in ACR, at 3200Ws:
and then at 1600Ws:
The Broncolor also gives us the worst performance, not surprisingly at minimum duration with the Color Control off. Not only is there a serious hit from one exposure to another, but there’s a different spread between channels - the red drops 4 points, the green 7, and the blue drops a whopping 9.
The worst results from the Profoto were at 1200WS - a shift of all channels down about 3 points.
There is variation from head to head and from channel to channel, but not more than what we’re seeing just from flash to flash, making it pretty difficult to come to any conclusions about where any variations are coming from.
Here’s what we’re taking from this. The Broncolor system has remarkable performance within one small piece of the test range, in this case, ironically, at the highest power. It holds the place of both the highest accuracy and consistency, and the lowest when shot with the Color Control turned off. The Profoto system has a fairly consistent margin of error throughout its power range. It’s interesting that these conclusions run parallel to what we saw in the duration testing. One system, the Broncolor, is quite remarkable within some fairly narrow parameters, and the other, the Profoto, has a more generalized, more consistent performance throughout its working range.