What will happen when a Nikon SB-800 in SU-4 mode (dumb optical slave mode) is placed amount a group of Canon flashes that are setup for Canon Wireless SpeedLite Flash system triggered by the Canon ST-E2 Speedlite Transmitter?

That’s what one guy tried to do and the result was interesting: The SB-800 seemed to work ok but all Canon flashes (a 580EX and a 430EX) refused to fire! How could this be?

Well, I offered an answer that is plausible. Basically, the Canon Wireless SpeedLite System (WSS) works in a similar fashion as the Nikon Advanced Wireless Lighting (AWL) system. The ST-E2 is equivalent to Nikon’s SU-800. Both systems use series of infrared pulses to communicate with and trigger the remote flashes. Canon’s communication protocol is incompatible with Nikon’s. That’s not the problem in this case though as the SB-800 was not setup as a CLS remote flash but as a dumb optical slave in SU-4 mode, which will fire upon seeing any light, including the infrared signal from the ST-E2. The light from the SB-800 is then seen by the Canon flashes. Because the light from the SB-800 cannot be perfectly in-sync with the ST-E2 pulse in terms of timing and duration, the Canon flashes will see extraneous signals and get confused. Read More…

Posted in Photography Lighting on April 24th, 2010. No Comments.

Most of you probably know that electromagnetic waves travel at the speed of light, which is 299,792,458 meters per second (in vacuum. It is slower in air or other media but that won’t really change the discussion). If you use a set of RF wireless triggers for remotely firing flash across a distance of 100 meters, a simple math tells you that it takes less than a microsecond for the signal to propagate. However, that’s not where the most delay comes from when a typical RF flash trigger is used.

The transmitter, sitting on the hot shoe of your camera or hooked up to the PC sync port, detects the change of voltage as the sync signal from camera, then sends command over the RF to the remote receiver. The receiver determines a correct trigger command has been received then it fires the connected flash. All of the above happens really fast but it still takes time. Read More…

Posted in Photography Lighting, Tips and Techniques on April 21st, 2010. No Comments.

If you have read our previous post titled Understanding Flash Sync Speed, you probably know what high speed sync (HSS) is. If not, or you need a refresh, read the post or watch this video instead. The following discussion of HSS may be a little too technical or detailed but the hope is to clarify some of the confusions I have seen in a few internet discussions. Read More…

Posted in Digital photography, Photography Lighting on April 17th, 2010. No Comments.

High speed sync (HSS) greatly expands the shooting freedom especially in bright daylight by allowing photographers to use wide aperture and fast shutter speed. I have covered this topic in a very popular post titled Understanding the Flash Sync Speed. If you want to see a clear explanation of the concept of high speed sync (HSS), here is a video produced by the folks who are behind the very popular Pocket Wizard MiniTT1 and FlexTT5 wireless flash trigger system.

The Pocket Wizard MiniTT1 transmitter and FlexTT5 transceiver mentioned in the video are wonderful in concept but are also very expensive: $199 for the MiniTT1 and $219 for the FlexTT5. For other remote flash triggering and power control systems, please see the recent post titled Remote Flash Wireless Triggering and Power Control.

Posted in Photography Lighting on April 8th, 2010. No Comments.

In order to achieve the best possible flash photography results, taking flash off the camera and using multiple flash units become necessary. For example a typical setup for studio portrait shooting may include key light, fill light, background light, and often hair light. Not all shooting situations require this many lights but it is safe to say triggering multiple lights and synchronizing the light output with the camera’s shutter is the solution the photographer need to find.

Typically corded connections between the camera and flashes are supported by most camera/flash systems but most photographers do not like the hassle of wires. The simplest form of wireless trigger is the inexpensive optical slave triggers. But very often they suffer from poor range and are prone to interference. One step up is radio frequency (RF) wireless flash triggers. These triggers can trigger the flash from long distance and do no require line-of-sight between the transmitter and receiver. Most of the low cost triggers (for example, check out our review of an eBay trigger iShoot PT-04 CN) do not support remote flash power adjustment. All the remote flashes need to be in manual mode. If the photographer needs to change the flash power, he/she needs to get to the flash and change it by using the controls on the flash. Sometimes this is an acceptable inconvenience but sometimes it is unacceptable because of the physical location of the remote flashes or the time required to do so.

This discussion will be focused on wireless triggering and remote power control options currently on the market. Read More…

Posted in Photography Lighting on March 24th, 2010. No Comments.

Camera flash pulses are typically very fast. It is fast enough to freeze motion even if you use a very slow shutter speed as long as the light from flash dominates the exposure.

Most camera flashes have xenon flashtubes. It lights up when the charge stored in a capacitor is discharged through xenon gas. The xenon gas is not very conductive in its normal state but its resistance can be greatly reduced when the xenon gas molecules are ionized, ignited by a high voltage pulse. The charges stored in the capacitor start to flow through the tube, giving out a very bright light. As the charge stored in capacitor discharges, the light intensity decreases.

The light intensity during a flash pulse isn’t constant. The light intensity emitted from the flash tube rises to a maximum quickly then fall off. If the charges stored in the capacitor are allowed to completely discharge, the light intensity will show a graduate reduction tail. Since we don’t want full power flash for each shot but rather just the right amount of light for proper exposure, the flash unit cuts off the discharge circuit at different times to control the amount of light emitted. Lower flash output power means shorter flash duration. Read More…

Posted in Photography Lighting on January 26th, 2010. 1 Comment.

The flash output level of a Nikon SB-600 Speedlight Flash can only be set to the minimal of 1/64 in manual mode. That leads many people to speculate the minimal output from the flash is 1/64. If you have used the Nikon Creative Lighting System (CLS) Advanced Wireless Lighting (AWL), you will know that you can use 1/128 output setting on the wireless commander unit. The wireless commander can be the built-in flash of your camera, or SU-800 commander, or SB-800/SB-900 Speedlight flashes. The question is what happens when the remote flash is a SB-600. Will it actually output 1/64 or 1/128 of light when the commander tells it to do 1/128?

To answer this question, I ran a test with a flash light meter to measure the output of the SB-600. Read More…

Posted in Photography Lighting, Q & A on January 20th, 2010. 2 Comments.

Before I got my first true Macro lens, a Sigma 105mm f/2.8 EX DG, I had a cheap way of getting macro shots: Mounting a Nikkor 50mm f/1.8D AF reversed using a reverse ring (Nikon BR-2A or the cheaper clone). The picture of that setup and sample image can be found here. Basically it worked OK. On my D200, the camera maintains auto-exposure but no more auto-focus. The images are quite sharp. The magnification is not high through.

Recently I acquired the 35mm f/1.8G AF-S DX, which is a nice prime lens for DX format Nikkon DSLR cameras that gives you a “normal” field of view. When I stumbled across the reverse adapter ring I purchased long time ago on a dusty shelf, I decided to try it with the Nikkor AF-S 35mm f/1.8G lens. Read More…

Posted in Tips and Techniques on January 18th, 2010. 10 Comments.
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