Cactus V5 review, radio flash trigger by Gadget Infinity

Harvest One Limited, through their Gadget Infinity web store, have been widely known for their Catus brand of radio triggers for "Strobist" use. The Cactus triggers were (are) an inexpensive way to get into off camera flash triggering with radio triggers. The earlier versions operated well enough under many limited range conditions but could sometimes be less reliable than desired. They also could be subject to radio frequency interference from newer flash designs that didn't want to play nice, like the Canon EX series. The basic design went through a number of changes and new models were released in order to address the reliability issue along with making the product more user friendly. While improvements were made the electronic design was basically the same but tweeked with every new version up until now.

The Cactus V5 trigger is a completely new design. Where the previous versions operated on 433MHz radio frequency the V5 uses the 2.4GHz band. Radio triggers that used the 433MHz band could experience interference and false triggering when used with RF noisy flashes. This could limit the already short range of operation for these triggers. In extreme cases (false triggering) they just couldn't be used. So the logical solution to the problem is to move to a frequency band that these noisy flashes don't radiate in. This is one of the reasons most of the recent triggers are now using the 2.4GHz band.


Moving to the 2.4GHz band does have some problems though. It costs more to produce the radios. And power consumption is a lot higher than the 433MHz designs. But if you want the range and the reliability it is the right way to go.

The Cactus V5 is a tranceiver design. That means that the trigger can be used as a transmitter or it can be used as a receiver. This is good from a user standpoint as well as for production. It is always good to have backup gear when you are doing a shoot. This way if an item fails you can switch it out and continue. With the previous trigger sets you had to have a transmitter and receivers for each of the flashes you wanted to use. So if you wanted a backup then you would have to have an extra transmitter along with an extra receiver. With the tranceiver design any backups that you have can be used for either purpose.

Because of the transceiver design you have a hotshoe connection on both the bottom and the top. The bottom is for triggering from your camera's hotshoe. The top can be used to fire a manual flash on camera if needed (or off camera when the V5 is set as a receiver). Only the X-sync / Fire pin is available so there are no auto-focus light or other TTL functions passed through. If you need an on camera flash with TTL functions you can trigger the V5 transmitter with a camera PC connection. Supplied with the kit is a PC to 3.5mm (1/8") mini phone cable that can be used for that purpose.


On previous Cactus triggers (and other brands as well) DIP switches are used to select the channel number. The V5 now has a rotary switch on the side of the unit for 16 channels. The first five channels are labeled (1-5) in blue and the remaining (6-16) are in white. The first five channels can be used in a new multi-channel triggering mode.

The rotary channel selector is conveniently located on the side of the unit. This is a good thing if you are going to make use of the multi-channel triggering option.

In multi-triggering mode any receivers set on channels 1-5 will fire when the transmitter is set for channel 1. This is similar to the "all channel" mode on the Yongnuo RF-602. Having this effect only a few channels gives a little more flexibility as not all triggers will be fired.


One way to use this feature is to have each trigger/flash on it's own channel. You could fire each one individually and see the effect of each of the lights. By setting the trigger to channel 1 then they all will fire (channels 1-5) to give you the composite result.


Another way to use this option is to have multiple flashes in one group (that can be used on their own) and a second group on their own, and then the big the big finale with all flashes firing.

What makes this practical is the channel selector dial. Most triggers require you to change dip (dual inline package) switches to change the channel. On some triggers you need a pointy object to change the switch settings. On a lot of thriggers the switches are hard to get at. You have to take the trigger off the camera and turn it over to change the channel. But on the Cactus V5 all you have to do is spin the rotary dial that is located on the side of the trigger. And if you are using adjacent channel numbers then it is very fast to click to the next channel. Just one of the nice improvements that make the trigger more user friendly.

As a transmitter the V5 can be triggered by the bottom hot shoe connection. It can also be triggered by the 1/8" (3.5mm) mini connector shown above. (the hole to the left of the TX/off/RX switch) 

When the V5 is triggered it will fire the top hot shoe connection allowing a manual flash to be used on camera. As a number of people have discovered the top shoe connection can also fire another non-V5 transmitter. So if you needed to, you could fire a parallel system (if it didn't use the same frequency as the V5) if you were short of V5 receivers.

As a receiver the top shoe mount can fire a flash (obviously). The 1/8" (3.5 mm) mini jack can also be used to fire a flash. But wait, there's more. You can fire a flash from the top shoe connection and you can fire an additional flash from the mini jack at the same time.

That is what I have done in the image below. My Canon 580EX has been modified to use a mini jack as an external trigger input. So I used the supplied mini to mini cable. If my flash instead had a PC connector I could use the supplied PC to mini connector. But if you do run two flashes in this way make sure the trigger voltages are close if not the same (+/- 20%) as the two points are electrically connected to each other.

So there are a lot of triggering options with the Cactus V5. The V5 Duo kit also includes a 1/8" mini to 1/4" phone adapter so you can use it with studio strobes that use that connector for triggering. Shown below are the cables and also a booklet  When Light Dances 2 that has 18 images and the details about how they were created.

The Cactus V5 does a great job as a flash trigger but it can also be used as a camera shutter release trigger. Because there are a number of different connectors used for external triggering of cameras (even by the same camera maker) the cables will be sold seperately.

I have the shutter release cable they make for my Canon camera (30D). The shutter release function works pretty well. The V5 has a two position test button just like your camera shutter button. So on the V5 you do a half press to focus the camera and a full press to release the shutter. Just like the camera.

Holding down the test button holds the receiver output on so it can also be used for longer shutter times if you set your camera for bulb mode. If you want to do a long exposure the V5 will stay on when you hold the button for more than two seconds. To release it you just press the button again.

The Cactus V5 has a rated operating range of up to 100 meters. I feel that that is a conservative figure but better to underrate than overrate the range. While I have not done a lot of long range testing I have had reliable operation out to 200 meters. This was the limit under the conditions I tested it. It did fire further than that but it soon became unreliable. But I really didn't expect it to even get this far.

Another nice feature is the extended temperture range rating. The V5 is rate from -20^°C to +50^°C. I was only able to test out the cold end. (did I ever tell you I hate the cold) Unfortunately the long range testing was done out in the cold as well. I have not yet tested out the high temperture end but if anyone wants to send me somewhere hot then please please send me a note, soon!

So the V5 works well outdoors but what about indoors? I brought the V5 Duo to work and tested it out on the factory floor. Lots of computers, and other electronics, metal studs in the walls. Lots of shelving. I put the receiver in one blind corner at one end of the building and triggered it from the opposite corner. Sort of an L shape with the trigger on the long end and the light on the far end of the short side. The light was very dim in the illuminated corner due to the distance so the pictures didn't look that great so I didn't save them. A shelf full of cardboard boxes was pretty unexciting. Maybe If I had used some gels? But the receiver did hear the transmitter and did fire the light as required. 

OK now for some technical measurements. The following is an electrical timing plot with the input to the transmitter trigger on the top trace and the bottom trace is the output trigger signal of the receiver. The normal inactive state is high. When you put a low on the input of the transmitter it sends a radio signal out and the receivers hear the signal and decode it and if it was a match for it's channel number then it in turn puts a low on the receiver's output.

So the meaured delay from input to output was 730 micro-seconds. That's pretty good. A little slower than my V1 triggers ( they were 620 micro seconds) but still quite acceptable. So what does this mean? The trigger delay will start eating into your sync speed. All radio triggers do this. But if the camera manufacture was not cutting the time real close most triggers will not cause a reduction in the sync speed.

The following were flash exposures on a Canon 30D with the flash on camera (right side) and with a flash triggered with the V5. Shutter speeds from 1/500s to 1/250s were tested. The 30D has a rated sync speed of 1/250th of a second.

The difference between the black bands is caused by the delay caused by the radio trigger. The flash used was a Canon 580EX. The exposure differences (white areas) were due to my inconsistant distance from the wall I was shooting at. But it does not have any effect on the results.

The 1/320 second shutter speed is really interesting. If I have a dumb flash (no TTL connections) triggered by the 30D (direct X-sync connection or PC port) I get a sync speed of 1/320s rather than the advertised 1/250s. Even with the V5 in the loop I get most of the frame exposed. So as long as I have the flash exposing the subject in the white area I can use 1/320s rather than the 1/250s I thought was my limit. 

And for the listed sync speed I get the full frame exposed even with the V5 radio delay.

So I wanted to test how the V5 handles continuous burst shooting. I had first tested this with my flash on low power and my camera set for it's maximum frame rate of 5 frames per second. No, not the fastest but it was a first test. I forget the number of frames I was able to do but the timing between flash bursts appeared to be the same so it looked like it handled it well. But like I said, 5 fps is not that fast.

So I took it to work and tested it with a signal generator for an input to the trigger. Now the next trace is interesting. Again, the top trace is the trigger signal to the transmitter. The bottom is the output of the receiver. This was the maximum continuous frame rate that the V5 can fire without losing frames.

I had to check this a second time to make sure I wasn't confused with the results. And it all checked out. The maximum frame rate the V5 can handle without droping frames is 39 frames per second! Wow. I think it will be a long time before we see a consumer camera that can use that flash rate. You can probably shoot video with a radio link if you had a suitable strobe.

Just a few more details about the triggers. These triggers can be safely used with high trigger voltage flash/strobes. The rating is for up to 300 volts. The polarity of the flash/strobe is positive on the tip if you are using a cable to trigger the flash, and positive in the center fire pin on the hotshoe.

The Cactus V5 Duo comes with two pair of AAA alkaline batteries. You can also use NiMH batteries as well. As I mentioned at the start of the post, these triggers draw more current than the previous Cactus (and ebay) triggers. When set as a transmitter the ready state draws about 2 mA and when transmitting it goes up to about 10 mA. Receive is a different story (although not unusual for a 2.4 GHz trigger). The current draw is about 22 mA and then jumps to 28 mA when it receives a valid fire command. So you need to keep in mind that you must turn off your triggers after the shoot. A habit I will need to work on.

The V5 does have a low battery detection circuit. It will flash it's status light Red when your batteries are low. Even so I still had no problems when the batteries were discharged down to 1.0 volts each. The radio chip set they use in the design is rated down to 1.8 volts as a minimum operating voltage. The micro-controller used has a minimum spec of 2.0 volts. So under load the pair of batteries would have to put out a minimum of 2.0 volts. But you really don't want to run them that low. While I have not accurately tested this I would estimate that you could get about 48 hours from a set of alkaline batteries assuming a 1200 mAh rating.

In the end I think the Cactus V5 is a pretty good trigger system. (it needs to be considering the number of triggers it is competing against) It has quite a number of good features. The design look solid. Having looked at the electronics (and the schematic they show in their video) it looks like a good platform for them to build on. I'm thinking a future Catus trigger could have manual power control from the transmitter (like the Radio Popper JrX) and maybe more grouping options. But for now the Cactus V5 may not give me give me all I want but it gives me what I need.