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Review of Lencarta SF600 Flash Head




What Are We Looking At?

The new Lencarta SF600 is an interesting proposition. It’s an IGBT based head which claims a higher guide number than any other monoblock IGBT design that I’m aware of. I’ve reviewed several IGBT based heads before, the main selling point of this type of head is that as the flash power is reduced the flash duration drops dramatically. So at low powers it’s not uncommon to get flash durations of 1/10,000 second, which are great for freezing action, as often demonstrated with pictures of models having milk or water thrown over them. Other less heavily touted benefits include much faster recycle times as the power is reduced so at lower powers frame rates of a few shots per second can be achieved. This is actually quite a big benefit compared to standard flash heads because it means you can shot in a much more spontaneous fashion in the studio and not really have to worry about waiting for the heads to recharge. Another characteristic of this type of flash is that you don’t get auto-dumping into the flash tube as you reduce the power level, something I’ve always found my models dislike.

The question of course is will the SF600 come up with the goods?


Build Quality And General Comments

Lencarta SF600 Side View 1

Side view of head

The initial impression I got when I received this head was of it being built like a tank. It’s very solid, heavy and feels extremely robust. The user interface looks a little dated on initial inspection, with a two digit, 7 segment LED display for the power value, a rocker switch to turn the power off and on and 4 push buttons, for Optical Slave Mode, Modelling Light, Beep and Test Flash. Each of these buttons has an LED above it so you can tell whether it’s selected or not. They’re labelled with red text on a black background so the text is far from easy to read in low light, but then there’s only 4 buttons, 3 of which I’d never use (the slave and beep as I dislike beeping and always have a radio receiver on every head because of how I work, and why use the test button on the head when you have one on the remote?) so I found within minutes of using the head I knew which button(s) did what so I didn’t need to be able to read the text on them.

One thing I was a little disappointed to see was that the SF600, and its little brother the SF300, only has 5 stops of adjustment range. I’ve griped about this before because I sometimes work in quite a small space and if I’m using a head as a hair light at close range I want to be able to turn it down to a guide number of 10m or less. C’est la vie, I guess you can’t have everything.

I also had a SuperFast Radio Trigger set to use with the head. This consists of a radio trigger (operating at 2.4GHz, the sample I had was 433MHz but current models are the higher frequency and have a greater range because of it) and a reciever that connects to the head via a USB socket. The trigger is nicely designed, it’s a Pocket Wizard style affair but is quite small and allows the user to fully control all aspects of the head, other than the intensity of the modelling light. This is something I really like, especially if it’s well implemented. The remote has a small, backlit LCD display that shows the power setting of the head under control. It has a knob that lets you set which flash ID you’re talking to, there are 16 in all and the heads can be grouped into sets if required. There are buttons for modelling light, beep, test, power up and power down. And also a set of dip switches that allow you to set the radio channel so you can operate two sets, or more, of these triggers in close proximity without cross triggering between the two set-ups.

It’s worth noting that Lencarta have used a somewhat non-standard notation for the power level on this head. There’s nothing wrong with it, it’s just different. Full power is indicated by the number 10, half power is 9, quarter power is 8 and so on down to 5 being the lowest power and then if you decrement the power level another notch it goes to off. I thought this was a bit odd to start with but it’s actually a really good idea because you can have multiple heads and turn any of them off from the remote by using the power setting. Another great idea, amazing how the simplest ideas can often be the most effective.

Lencarta claim a 200m range for these triggers, which I would have thought is far more than anyone is likely to actually require. The receiver has just the DIP switches and channel knob. One thing I would comment on, on the remote is that as you change flash IDs with the knob the remote remembers what power you last had that ID set to. What a good idea! This means it’s possible to remotely control several separate flashes and keep track of what they’re all set to, unlike the poor implementation that Strobeam have on their remote that means you can only viably control a single head, unless they're all set to the same power.

The remote set costs £70, that’s 1 trigger and 1 receiver. Extra receivers cost £25 each which is pretty cheap compared to the likes of Bowens. Personally I’d have a receiver on each head. The receiver is powered from the head so no need to worry about batteries at that end. The trigger takes a pair of AA batteries. There is also a standard trigger socket on the rear of the head if you do want to use an existing trigger set.

The controls on the head are fairly intuitive; there are 4 buttons, as I previously mentioned, all of which are self-explanatory, and two knobs. One knob adjusts power, as shown on the LED display, the other knob adjusts modelling light power. I like that interface, in fact I really like the whole user interface of this head. I was expecting this to be a problem area and I think Lencarta have taken a leaf out of Bowens’ book and just gone for a really simple effective user interface which just works and doesn’t make you feel you’re doing battle with it whenever you use it. In fact after using this head for a matter of minutes I felt completely at home with it and felt there was nothing that I would want to change about it. And to be honest this is the first head I’ve used that I can say that about. Kudos Lencarta.

The modelling light is a 150W halogen bulb. The modelling light and flash tube are covered with a Pyrex clip on cover. I guess this is in case the flash tube explodes under duress! It’s a good thing to have though and provides a first line of protection for the flash tube when changing modifiers.

Here are a few photos so you can get an idea of the size and build quality of the head and remote and also of the user interface.

Lencarta SF600 Remote

Remote control

Lencarta SF600 Side View 2

Front view showing the flash tube and halogen modeling light

Lencarta SF600 control panel

Close-up of the control panel with radio receiver


Power Setting Accuracy

Firstly I measured power setting accuracy. This head behaves much as I expected, but better, based on the performance of previous IGBT designs that I’ve looked at. The quoted guide number is 75m at full power but because of the nature of IGBT switched heads the light output has a long tail on it at full power, as you can see if you look at the scope traces a bit further down the page. This normally means it tends to be a bit non-linear when it goes from full power to half power. But no! That’s not the case here, the power is a little low at full power by my reckoning, I measured it at 64m rather than the quoted 75m. But I would not take that as gospel, I measure guide number with a standard reflector fitted at a distance of 2m on a mid grey background. Subtle things like the positioning of the flash tube in the head can affect the distribution of light over the target area, so although the light output may appear slightly low measured in this way it may not when measured differently. So what I’m saying is the power output of this head is close enough to be, in absolute terms, within the bounds measurement error. Either way it’s still the highest output IGBT head that I’ve ever measured.

I did, as a matter of interest, try the same power test with a 5' octobox, a notoriously lossy modifier because it has a double diffuser in it. Assuming a loss of 1 stop from the modifier, which is very conservative, I got a GN of about 67m, if I were to assume a loss of 1.5 stops from the modifier, which is probably more realistic, it would mean the SF600 had a GN of about 79m at full power. As I said, measurements of GN are not a precise science because they're so application specific. The conclusion being that the SF600 is close enough to the manufacturer's spec. to not quibble about.

Power Accuracy Results Table

Power Power Setting Quoted GN Actual GN % of Quoted
600W 10.0 75 64 85%
300W 9.0 53 47 89%
150W 8.0 38 35 95%
75W 7.0 27 24 92%
38W 6.0 19 18 95%
33W 5.8 17 17 95%
28W 5.6 16 13 83%
25W 5.4 15 10 63%
22W 5.2 14 7 47%
19W 5.0 13 5 41%

The power delivery is very linear for the first 4 stops and then it ramps down to a way lower power than it is spec’d to. You might expect me to be critical of this but frankly I’m over the moon! This means the head actually has 3 stops more adjustment range than quoted so it has an amazing 8 stops of adjustment range which is exactly what I wanted. It may not be intentional but I expect it probably will be consistent from head to head and is fantastic news as far as I’m concerned. It just means you do have to be aware of it as you adjust the power between 5.8 and 5.0.

With this in mind it's difficult to see why anyone would buy the SF300, it's only £50 less than the SF600, so just get the more powerful head, you'll be glad you did in the long run and of course if you shoot at half power on the SF600 rather than full power on the SF300 the recycle times half and the flash duration (t=0.1) drops by 3:1 as well. You're winning on all fronts for only a 15% more initial outlay, a bargain by any measure.


Colour Accuracy

The next test I did was colour accuracy. Here I measured the head’s Kelvin white balance at output power settings from full power to minimum power. Typically IGBT designs have a tendency to give a bluer light as the power is reduced, unless the manufacturer compensates for this by reducing the supply voltage as the power is reduced, as done in the Paul C Buff Einsteins. However, the SF600 does not suffer from this problem, the colour is consistent give or take 100k though the entire 8 stop range, which is an amazing performance, certainly far superior to the Strobeam G5 that I’ve previously reviewed.

Colour Accuracy Results Table

Power Power Setting Red Green Blue Kelvin White Balance
600W 10.0 77 76 77 5500
300W 9.0 77 76 77 5500
150W 8.0 77 76 77 5550
75W 7.0 77 76 76 5400
38W 6.0 77 76 76 5300
33W 5.8 77 77 77 5300
28W 5.6 77 76 77 5350
25W 5.4 77 76 77 5400
22W 5.2 77 76 77 5300
19W 5.0 77 76 77 5400

I’m delighted at this performance, it’s difficult to imagine this would cause anyone a problem. To be honest there's probably a measurement uncertainty of ±50 degrees Kelvin here anyway which means the white balance could well be within ±50 degrees Kelvin over the entire range, an amazing performance. I’m pretty sure this head has been compensated to achieve this level of colour accuracy over such a wide adjustment range.


Power Consistency

Here I’m checking that when set to a given level the SF600 consistently delivers the same power. This is actually quite an important parameter as I have seen cheap heads that can vary by almost a stop, shot to shot which isn’t great. And indeed not so cheap heads like several of the Strobeam products that when used in burst mode give a decreasing amount of light as the burst of flashes goes on.

The SF600 excels here as well. If you fire off a high speed burst of flashes (3 fps) at half power the head delivers, I only tested this for 9 consecutive shots, so 3 seconds. The output power is consistent to within 0.1 stops so pretty much negligible variation for any real world situation. I also tried 6fps at quarter and eighth power and got just as consistent results. Absolutely amazing performance that exceeds Lencarta’s specs in terms of the burst rate at half power.


Flash Duration

Flash duration is arguably one of the key attributes of the SF600. Well this is interesting and confirms my guess that the head is compensated to give very consistent white balance. What that means is that not only is the flash duration altered as the power is changed but also the voltage that is applied to the flash tube is changed. So as the power decreases, the flash duration is reduced and the voltage applied to the tube is also reduced so the flash duration does not decrease quite as quickly as you might expect. This is what Paul C Buff do in their colour consistency mode on the Einsteins. This means the bad news is that if you want super-fast flash durations of 1/10,000 second or faster this is not the head for you, but it’s unlikely many people will have a requirement for that. The good news is that even at full power the flash duration of the SF600 is very quick, about 3 times quicker than the Strobeam G5. It would have been nice if these heads had an option to select fast mode or colour consistent mode like the Einsteins. That way super-fast flash durations would have been an option for those who needed it.

You can see what I’m talking about on the scope traces below. The amplitude of the pulse of flash light drops very substantially as the power is reduced, but the flash duration doesn’t change that much after the first 3 stops of adjustment.

Lencarta SF600
600W T1
300W T1
150W T1
75W T1
38W T1
33W T1
28W T1
25W T1
22W T1
19W T1

Note: Oscilloscope traces showing the variation in flash duration (rollover the power values to show the different scope traces)

I’ve measured the SF600 head at 1 stop intervals from full power down to 1/16th power and from there on in 0.2 of a stop decrements. I've noted the t=0.5 and t=0.1 times. t=0.5, the time when output power has dropped to 50%, is what most manufactures quote because it makes them look good and is the industry standard, even though it’s not terribly useful. t=0.1, the time when output power has dropped to 10%, is a more practical figure if you want to compare it to an equivalent shutter speed, at this point the light level is just over 3 stops down so what little light is still coming out of the flash is not going to show very much on your moving subject.

Power Power Setting t = 0.5 t = 0.1
600W 10.0 0.600ms (1/1700th) 2.100ms (1/500th)
300W 9.0 0.630ms (1/1600th) 0.712ms (1/1400th)
150W 8.0 0.336ms (1/3000th) 0.424ms (1/2400th)
75W 7.0 0.290ms (1/3500th) 0.384ms (1/2600th)
38W 6.0 0.280ms (1/3600th) 0.352ms (1/2800th)
33W 5.8 0.264ms (1/3800th) 0.328ms (1/3000th)
28W 5.6 0.216ms (1/4600th) 0.272ms (1/3700th)
25W 5.4 0.176ms (1/5700th) 0.240ms (1/4200th)
22W 5.2 0.144ms (1/7000th) 0.232ms (1/4300th)
19W 5.0 0.104ms (1/9600th) 0.184ms (1/5400th)

Note: The flash durations are shown in ms and in brackets as fractions of a second

I guess this is the weak point, or more accurately the compromise that has been made with these heads. I think for most people it won’t really be a compromise because the fastest thing most people want to photograph is water and liquids splashing and at quarter power we’re still talking about 1/2400th second (T=0.1) and how many people shoot at shutter speeds faster than that? I think somewhere around 1/2000th second is fast enough to mostly freeze splashing liquids unless you’re very zoomed in.


Flash Recycle Time

Flash recycle time is definitely one of the major strong points of this head. The performance really is amazing, as commented elsewhere in this review. I could fire off a high speed burst of flashes at 3 fps at half power and the head delivers, I only tested this for 9 consecutive shots, so 3 seconds worth. The output power is consistent to within 0.1 stops so pretty much negligible variation for any real world situation. I also tried 6fps at quarter and eighth power and got just as consistent results. Absolutely amazing and performance that exceeds Lencarta’s specs.


Ease of Use

This is always a subjective area. But I’d have to say I love this head. It has a simple, effective user interface which doesn’t get in the way of using it. The remote is excellent and again does exactly what I want it to. Even for a photographer who doesn’t require short flash durations I think I’d still recommend these heads. Not least because of the lightning fast recharge times at lower powers. It means you can forget you’re operating with flash heads and just press the shutter release whenever you wish and know the heads will be charged and ready.


Conclusion

This is easy. I love these heads, as simple as that. I’ve been looking for a while for a new set of heads for my studio and simply put these are the ones. I was expecting the user interface to be somewhat lacking but it’s not, it’s excellent. I was expecting to have to live with the limited adjustment range, and assuming the sample head I’ve looked at is typical, that’s not an issue either. I never even realised what a benefit being able to turn a head off via the power setting would be until I had it, and it’s great.

In the nature of fairness I’m trying to think of something negative to say about this head but I’m struggling a bit. I guess using the remote to change from full power to lowest power takes several seconds, but then if it was much quicker it would be difficult to adjust accurately so that’s more an observation than a criticism. I suppose it would be nice to have the power display on the side of the head so it could be seen in use but the remote is excellent so that’s not really necessary either. If you really need super-fast flash durations, by which I mean 1/10,000th second or faster, these heads will not give you those but instead what you get is very fast flash durations at full power. So you've exchanged super-fast flash durations at very lower power for much faster flash durations, than the competition, at higher powers. That may not suit everyone but I'm guessing it's more useful to 90% of photographers than the other way around.

To be honest I’m searching for criticisms here and frankly I’m struggling to find any. Can there be any greater endorsement of a product than not being able to say anything negative about it? I’d say probably not. I’ll give you a list of pros and try and think of some cons but my opinion, as you will have gathered by now, is overwhelmingly positive.

Pros
  1. Class leading GN of 64m
  2. Amazingly fast recharge times, especially at lower powers but even at half power
  3. Excellent colour consistency
  4. Short flash durations at high power
  5. Superb high frame rate performance and power consistancy
  6. Excellent remote
  7. Excellent user interface
Cons
  1. Slower flash durations at lower power than competitive products

As you can see from above there are a lot of positives and really only one negative, a negative that probably doesn't impact that many people.

So in summary as I’ve already said I do really like these heads. In real world applications they do pretty much everything right. If you really want shorter flash durations than these heads deliver you’re probably better off using hot shoe flash guns and you’re going to be getting very low guide numbers whatever solution you find.

There’s not a lot else I can say against these heads. They work amazingly well in pretty much every area that people actually care about. I have to take my hat off to Lencarta, the SF600 has considerably exceeded my expectations. I really wanted it to be a panacea and deliver on all fronts and in all honesty didn’t think it would. But I was wrong, it’s a great product and I love it and the proof of the pudding will be that I’ll almost certainly be putting my hand in my pocket and buying a set of these for my studio.

Well done Lencarta I take my hat off to you.


About the Author

By trade I’m an electronics design engineer hence the quite technical nature of this review. I like to know exactly what a product delivers so I know how I can rely on it and how I can use it. I hope this review is of assistance to anyone else who is considering buying one of these heads