Broncolor Senso Power Packs

Swiss lighting manufacturer Bron Elektronik AG, better known as Broncolor, has a well deserved reputation for producing some of the finest, most technically advanced electronic flash power packs available. With various lines offering extremely short flash duration, variable color temperature, adjustable flash duration, very fast recharging, battery power or various combinations of these features, Broncolor packs are also among the world’s most expensive.

Enter the Broncolor Senso line of power packs. By selectively scaling back some features, Broncolor has created a line of packs and associated Litos lampheads that allow a lower cost entry into the extensive Bron lighting family of products. Of course, “lower cost” is relative, but the Senso/Litos line is priced competitively with the Profoto Acute line, and offers some advantages in the comparison.

Two Senso packs are available. The Senso A2 delivers a maximum of 1200 joules (or watt-seconds) that is delivered either symmetrically or asymmetrically into a maximum of three lampheads. The Senso A4 delivers a maximum of 2400 joules in the same manner. While the Senso packs are compatible with Broncolor Pulso G and Unilite lampheads, for shortest flash duration (an issue with the Senso packs) Bron recommends the specially designed Litos heads, which are compatible only with the Senso packs. The Litos heads are also in keeping with the relatively compact sizes of the Senso packs, and Litos heads are supplied in the Senso kits.

Bron provided the Senso Kit 22 for evaluation. It consists of a Senso A2 power pack, two Litos lampheads, one 28-inch square Flex softbox, a sync cable, power cord and case. It makes for an impressive, if somewhat weighty, location kit, although I don’t understand why only one softbox is provided for two heads. I ended up taking two umbrellas with me for location shooting.

Bron also provided a compact RFS 2 radio transceiver. RFS 2 receivers are built into the packs, but the transceiver is an accessory. The RFS 2 system proved 100 percent reliable both on location and in the studio and it is a welcome advance from Broncolor’s previous infrared triggering system.

Unpacking the kit, I was immediately impressed by the look and feel of the A2 pack. It is Bron’s entry-level power pack, but there are no exposed screws, and no protruding rotary switches or antenna, as found in the competition. The corners of the pack are finished with rubber bumpers and the pack has a quite different look than the more utilitarian-looking Profoto packs. I liked the Senso even before powering it up.

Lampheads attach to the side of the Senso pack, with their cords exiting toward the floor, again giving the pack a cleaner look and preventing the art director from tripping over a cord that on other packs exits from the top or side and makes a lazy loop to the floor. Attaching, and especially removing, the rather long rectangular lamphead connectors takes a little getting used to if you haven’t used Broncolor packs. This quickly becomes second nature and you come to appreciate the solid feel and confidence of knowing the connection is securely fastened.

The Senso A2 pack itself is loaded with features, yet it is quite possible to simply unpack it, attach lampheads and start shooting. Two bright blue LED readouts indicate the power setting of the two channels. [IMAGE FrontSenso.jpg] These readouts can be set to read in either f-stops or watt-seconds. The three lampheads can be set to operate with equal power (symmetrically) or with one head at a different power setting than the other two (asymmetrically).

Distributing power to the heads is very intuitive and offers tighter control than the competition. Each of the channels has a three-way rocker switch for full, half, or quarter power. In addition, a pair of buttons for each channel offers adjustment over an additional two-and-a-half-stop range. A quick press of the button adjusts the power in 1/10-stop increments, while holding the button down adjusts power in full stops. Power levels are automatically increased or dumped with no further action required from the user.

Other buttons on the top of the pack control the radio channel selection, recycling speed, sound options, flash triggering options, modeling light options and of course a large backlit test firing button. Buttons have a solid feel when you press them and Bron says they are dust and moisture resistant.

In use, I observed at least two areas where Broncolor cut down on costs: color temperature and flash duration. The Bron spec for color temperature variation of +/- 100 degrees Kelvin over three f-stops is accurate from my measurements. The color temperature varied no more that 100 degrees Kelvin from the middle f-stop to the power setting one stop higher and one stop lower. However, over the full f-stop range, the color temperature varied by 300 degrees Kelvin. Where variations of 100 degrees are visible in critical situations with digital capture, this could be an issue for some photographers.

More of an issue is flash duration—particularly for medium- format digital photographers using leaf shutter lenses—but even for digital SLR users with flash sync speeds of 1/200 or 1/250 second. I noticed this issue when shooting a model in the studio using the full 1200 J from the A2. I normally use a shutter speed of 1/250 in this situation and the captures looked slightly underexposed. Opening up the aperture half a stop seemed to solve the problem. Checking the A2 specs later I found that the flash duration at full power is only 1/180 second with the Litos head I was using and 1/100 second had I been using a Pulso G or Unilite head. So a shutter speed of 1/250 was not capturing the full output of the pack. Further testing showed that I should use a shutter speed of 1/100 or longer to fully utilize the full output of the pack. Unless you are attempting to capture fast action or balancing with bright ambient light, flash duration probably won’t be an issue, or you can work around it like I did. But it’s worth mentioning because this seems to be the only really significant shortcoming that some photographers might find in the Senso A2 pack. For the record, the Profoto Acute2 exhibits the same behavior.

The Broncolor Senso Kit 22 has a street price of about $4,300. The Senso A2 Power Pack is available separately for $1,950 and each Litos lamphead for $1,780. Additional information is available at www.broncolor.com.

Specifications

Senso A2 Power Pack

• flash energy: 1200 J
• f-stop: 32 1/10 (with Litos reflector), 45 8/10 (with P70 reflector) @ 2 meters, ISO 100
• flash duration up to 1/600 s (t 0.5), 1/180 s (t 0.1)
• charging time: 0.4 – 1.5 s
• control range over 6.5 f-stops in 1/10 f-stop intervals

Senso A4 Power Pack

• flash energy: 2400 J
• f-stop: 45 1/10 (with Litos reflector), 64 8/10 (with P70 reflector) @ 2 meters, ISO 100
• flash duration up to 1/300 s (t 0.5), 1/90 s (t 0.1)
• charging time: 0.4 – 2.8 s
• control range over 6.5 f-stops in 1/10 f-stop intervals

Stan Sholik is a commercial/advertising photographer in Santa Ana, CA, specializing in still life and macro photography. His fifth book, Nik HDR Efex Pro, for Wiley Publishing, came out in October.