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Imalent is a relatively new flashlight manufacturer, and has debuted with a set of lights that feature a touch screen based user interface. The SA04 sports four separate emitters: a cool white XM-L2 and a warm XM-L2 for variable a variable tint main beam, and two red/green/blue combo emitters.
Thanks to Imalent for providing the SA04 for review.
I’ll be reviewing the SA04 in two sections: first, I’ll discuss the light objectively (the facts about the light itself), then I’ll discuss the light subjectively (my impressions about the light's performance when used for specific applications). If you have any other specific applications you'd like the light tested for, let me know and I'll see what I can do.
Video Review
Below is a video review of the SA04. Due to my old image hosting site closing down, I've got new restrictions on image uploads and have replaced the "Construction" section of my reviews with a more detailed video review.
https://www.youtube.com/watch?v=7aYRI3tTaeQ
This video is available in 1080p HD, but defaults to a lower quality. To select the playback quality click the settings button (looks like a gear) after you've started the video.
Objective
Manufacturer's Specifications
Price: 93 USD
Product Manual
Dimensions
Plus, here's a few shots with some good detail.
User Interface
The SA04 has four emitters controlled by two physical buttons and a touch screen. It is capable of producing a wide range of tints for it's main beam by adjusting the outputs of the cool and warm emitter. The main beam overall brightness can be adjusted, and it can also be set to Strobe, Beacon, or SOS (all brightness and tint adjustable). It also has Red, Blue, and Green modes (not flashy or adjustable). To discuss the UI in detail here would be tedious and redundant, so instead of typing the whole thing I refer you to the video at the beginning of the review.
Action Shots
You can click on any of these shots to see them full size.
Tint Shifting (Many arbitrary positions)
Light in Hand
MugShot
BeamSlice
White Wall
ISO 100, f/3.5, 1/20"
When very close to the target, you can see the separate beams and their convergence.
For a cool, neutral, and warm tint I took a shot of the max and min brightness, and two arbitrary medium brightnesses in between.
Indoor Shots
ISO 100, f/3.5, 1"
For a cool, neutral, and warm tint I took a shot of the max and min brightness, and two arbitrary medium brightnesses in between.
Outdoor Shots
ISO 100, f/3.5, 2.5"
For a cool, neutral, and warm tint I took a shot of the max and min brightness, and two arbitrary medium brightnesses in between.
Performance
Submersion: Imalent claims IPX-8, but the switches and screen make me nervous, so I have not yet tested this claim.
Heat: The SA04 steps down in brightness after about 3 minutes, so heat is not an issue.
PWM: I detected no PWM on any output level of any emitter of the SA04.
Drop: I dropped the SA04 from about a meter onto various surfaces (including grass, carpet, dirt, and hard wood), and found no cosmetic or functional damage. However, I do recommend care because it seems a fall on a bad angle could crack the screen.
Reverse Polarity Protection: The SA04 claims reverse polarity protection, so I inserted the batteries backwards and tried to turn the light on, then corrected the batteries and the SA04 resumed normal function with no evidence of damage.
Over-Discharge Protection: The SA04 has a battery level indicator on the screen, which displays a decreasing number of bars then begins to flash when the battery level drops, and this is your cue to change the batteries.
Spectral Analysis
All light that we see as white is actually made up of several different colors put together. The relative intensities of the different colors in the mix are what determine the tint of the white we see. For example, cool white LED's have a lot of blue, and warm white LED's have more red or yellow. This measurement was done on a home made spectrometer. The plot below the picture is corrected for the spectral sensitivity of the human eye. Note: the peak in the 900nm region doesn't really exist, it's a piece of the second-order spectrum that's showing up here because of the high intensity of the light source.
The colored emitters:
Additionally, I've included the comparison of the maximally cool, maximally warm, and even (neutral) balance alongside the colored modes. Remember that many tints in between the extremes can also be achieved:
I apologize for the misleading color coding, the spectrometer software picks the line colors without asking my opinion 
Output and Runtime
ANSI FL-1 runtime ratings are the time it takes for a light to fall to 10% of it's original output (counting from 30 seconds after turning the light on).
The vertical axis of the graphs below represents a relative brightness measurement using a home made light box. The horizontal axis is time in hours:minutes:seconds. Runtimes are stated in hours:minutes:seconds. These graphs may be truncated to show detail.
As you can see in the chart above and in the graphs below, the max cool mode can get brighter than the max warm mode, and the max both mode is not the sum of the two. Most likely there is some maximum current the circuitry can provide, and of course the cool emitter is more efficient with that current so it is brighter when receiving max current. When the emitters are balanced, they likely both receive about half of the max current, and operate a bit more efficiently than then would at higher currents, thus giving a brightness greater than either one singly, but not the sum of the two.
Mode Comparison
Max Cool
Max Both
Max Warm
Throwing Distance
ANSI FL-1 standard for stating a light's throwing distance is the distance at which the peak beam intensity (usually at the center of the beam) is 0.25 lux. I calculate throwing distance and candela (lux at 1 meter) by measuring peak beam intensity at five different distances and using the formula lux*distance^2=constant.
If you take the time to calculate that the ratios here don't quite match up with the ratios of the lumen outputs, good job you 
. I believe that the two separate beams were not quite joined up at the distances I measured for the throw, and I expect the ratios would match better if I were able to measure the throw at a longer distance.
Subjective Review
Quick break down:
+ Variable tint
+ R, G, B beams
+ High brightness
+ Variable brightness
+ Large tint range
+ Large brightness range
+ Touch screen
+ Compact
+ Powered by common AA's
+ Dual front beams converge nicely
- RGB beams ringy
- UI takes time to learn
- Jumpy regulation
As far as I know, this flashlight is truly one of a kind. Not only does it use a touch screen to control it's many output options, but I can't think of any other light that effectively has a variable tint main beam. It isn't too uncommon for a light to have multiple emitters, sometimes of differing tints, but here Imalent has designed them so that two emitters of very different tints contribute to the same beam, and the relative brightness of the two emitters is adjustable so that the combined beam can have the a tint anywhere in between the two. The cool beam is very cool, not quite where I would call bluish but very close. The warm beam is extremely warm, probably one of the warmest I own, and certainly warmer than many incandescents. I usually put the slider about halfway between the midpoint and the fully warm end, giving a beam that's a bit warmer than what I consider neutral.
Many of us are familiar with variable brightness flashlights. Almost all high-end modern flashlights have multiple brightness levels to choose from, and there are now many options for lights with "infinitely variable brightness" - so many brightness levels that the transition between them appears smooth and stepless. The biggest contributor to the usefulness of an infinitely variable brightness light is it's user interface. I've already covered the SA04 interface in detail in the video review, so I won't re-hash how it works, but I do want to make some comments. Until now, there have just been two ways to adjust infinitely variable brightness that I can think of. The first was done by holding a button, and the light would ramp up or down, and you'd give a signal to stop when you wanted, kind of like playing a slot machine 
. Obviously not them most convenient method for controlling infinite brightness. Then, we saw the magnetic control ring, which allowed a user to rotate a physical ring in either direction to increase or decrease the brightness at will. This was an infinitely superior method of controlling infinite brightness, because the user was given complete control to fine tune to the desired output, and you never had to pass through settings too bright on your way to a dim setting, or vice versa. Now, we're seeing control of infinite brightness using a touch screen, similar to what many of us are familiar with on our modern phones or tables, but on a smaller scale. There are quite a few advantages and disadvantages of the touch screen interface, and because I see the control ring as it's main competitor, I'll focus on that comparison. First, the control ring has the advantage of being easier to manipulate with gloves or cold/wet fingers, etc., being a physical mechanism. The control ring also is more intuitive for the same reason, an so far has been easier for me to use without really thinking about it. The touch screen has the advantage of giving visual indication of the chosen output level, and also requires no moving parts. I am very curios to see how the screen holds up under long term use and abuse, but so far it has survived my drop test, and of my three Imalent light's I've tested, only one has a small scratch on the screen from being in my bag with other objects. It seems to me that the screen will be more resistant to things like dirt and grit, where the ring would be more resistant to impacts. I've never yet had a failure of a control ring on any of my lights, but I've read several reports of such, so we'll see how well the touch screen holds up in comparison over the long term. Next, so far the control ring has the advantage of smoothness of control, as the touch screen can make the output a bit jumpy due to my large fingers and it's relatively small size. In the end though, the biggest possible advantage and disadvantage of the touch screen is going to be it's versatility. So far, Imalent has used the screen to adjust infinitely variable brightness, make mode changes, and display the battery level. However, there are potentially many more was of implementing the screen to display various information, control various functions, etc. Depending on how well these functions are implemented (or not), the screen has the potential for surpassing usefulness, as we've seen in the area of mobile phones.
So, for the SA04 in particular, the interface is a bit tricky to get used to, as I expected for it's combination of two physical buttons with a touch screen that has a brightness slider and another on-screen button. However, once you practice with it a bit, it gets pretty comfortable, and I wouldn't hesitate to use it in a high pressure situation. If desired, you can choose the tint you like best and from then on it can be easily used only as an adjustable brightness light, and you can ignore the extra emitters and flashy modes without much fear of activating them by accident, which I consider to be an important feature. I found that after testing, I mostly left it on the same tint setting and rarely fiddled with it much, though I did have a few situations where I switched from my warm-ish setting to neutral to get maximum brightness for seeing something far away. This light has opened up some fun possibilities for testing my tint preferences and the usefulness of various tints for different tasks.
As I touched on earlier, the tint range for the SA04 is great, and I don't think I'd ever need a warmer or cooler beam than is available. In addition, the brightness range is excellent, reaching from about 0.1 lumens to almost 900 lumens. In my testing it didn't quite reach the claimed 930 lumens, but at this brightness that small of a lumen difference is very hard to see, so I don't feel like I'm missing out on anything. This does bing up one of the negatives though, and that's the jumpy regulation pattern. I understand the initial 3 minute stepdown, this is a standard feature for many high brightness lights, and is pretty understandable when using AA's instead of lithium ion batteries. However, after the stepdown the brightness is rather erratic. There is an attempt at regulation, which I appreciate, but I'd like to see some of the smarts used to design the rest of this light and have them work out some flat regulation patterns .
The only other bigger improvement I'd like to see is with the RGB emitters. I can't see what's going on inside the head and how much of the space is filled with electronics and such for all the modes and the touch screen, but looking from the outside, the RGB emitters are just mounted on a flat portion of the reflector. I'll put the picture here again for reference:
I'd like to see the RGB emitters set down a bit further into the surface of the reflector, and that flat portion made into a small parabolic reflector for each, or possibly covered with a soft diffuser. As it is, the RBG beams a very ringy, and it looks like there is room in the head to fix that. Most RGB beams I've seen on other lights are very ringy as well, but with the extra room here in the reflector surface I think the SA04 has room to smooth them out.
The other points to mention are that this light is pretty compact, even with all it's extra features, and it uses four AA batteries, which are very common and easy to find. The overall construction of the SA04 seems very solid, and the style is appealing. It's heat dissipation fins are a bit shallow, but with the 3 minute stepdown heat is never a problem.
Overall, the SA04 is certainly a unique light, and I'm impressed with the way that Imalent has included so many features in such a compact form, and managed to keep them all working smoothly! There is no other light I know that can do what this one can, so if the variable tint, variable brightness, and RGB options look good to you, then this is the light you want!
Long Term Impressions
I'll fill this part in after carrying the light for a while. If nothing get's added here, either I find nothing else worth noting about the light, or I end up not using it often.
Very nice review! I like what the spectral analysis adds to the review. I had that in my "to buy" list. I may be moving soon, and I plan to do more flashlight reviews in the new city and use that tool in my tests.
I kind of wish they designed this light, still using 4×AA, but with a single LED. I’ve heard talk that this dual color emitter would be nice for photographers, but honestly, how high if a demand is there for something like this. Maybe it’s just cause I’m not the biggest fan of that yellow tint.
Thanks for the review. This new brand of lights have really caught my eye recently and it’s great to see a detailed review of the pros and cons along with the UI. Keep up the good work.
Yep, doing the spectrum is a lot of fun, and can be very insightful as well!
Yeah, I’m not sure yet what the practical uses of adjustable tint will be. For me, I usually set the tint to one I like and just leave it there.
Just found your review..
FYI, your warm xml is NOT an XML2, but an older XML, just like mine.
see here: https://budgetlightforum.com/t/-/27930
Hey, it looks like you’re right, thanks for catching that!
Nice review.
Just an FYI mine has both XM-L2’s (verified by disassembling) and a metal reflector so there seems to be quite a bit of discrepancy. Mine is also completely water resistant.
Best part, the display uses a pretty standard PIC 18Fxxxx display driver so I’ll be able to eventually have all custom graphic’s and buttons!
Could you post a few pics? Im very curious about the metal reflector
That’s the absolute joy of this light and the whole point. 
You are able, with one light, to get EXACTLY the tint you prefer with no compromise at all. This light is truly perfect for ALL users no matter their tint preference (within reason 
).
Very nice review, quite a niche light though. I also like the spectra. Did you use one of the public Lab spectrometers?
Thanks! Yes, I use the publiclab Web app with a modified spectrometer design. 
I will be adding interior pic’s to Jmac’s review.
In the mean time worth noting; the inside of the light was very dirty, the only surfaces not covered in flux residue were covered in sticky tape residue. Also they couldn’t seem to make up their minds between using Kapton as an insulator or plain old electrical tape, there were multiple instances of both.
That's funny! So there is more to it.. Not just the few things I've noticed during my review.
Damn. Expensive!
Thanks, and I want to know more 
, not to criticize anything (I think it is great to do such a thing that you do), but I am curious about these kind of measurements and I am thinking of building a spectral wavelength measurement set-up myself. Do you use the piece of cd as a diffraction grating, or something else, or even a prisma (your spectra look very smooth). And what is the unit in which the different wavelengths are measured (before correcting for the human sensitivity curve), is it a representation of the optical power, or of the nr. of photons, or plainly the values of the pixels of the camera (and what are the pixel values representing at all)? And is the V(lambda) correction tailored for how and what is measured by the spectrometer? Is the grid used transparant for all measured wavelengths? Sorry for the multitude of questions 
.
No trouble with questions ;). I actually use a piece of DVD for the diffraction grating—they have more tightly packed lines, so the spectra I get are smother than those from CD’s. I’m working on an upgraded design, one of the features being a different diffraction grating, something more like this. A DVD has about 1350 lines/mm, a CD has about 625 lines/mm, and that one I linked to is in between with 1000. So, the resolution won’t be as good as with the DVD, but it has the advantage of being straight-lined (and still pretty cheap). Because the lines on the DVD are curved, the spectrum bands are curved, so when I calibrate a certain x-coordinate on my camera readout to associate it with a certain wavelength, it only works when taking the spectrum from the exact y-coordinate I calibrated on (does that make sense? I’ll upload a picture if I need to). With a straight grating, the bands won’t be curved so that will actually remove more error from my measurements than what is lost by the lower lines/mm.
When the data comes in from the webcam, it just reads the relative brightness observed by each pixel on the camera (in each of it’s separate red, green, and sensors). The red, green, and blue values from each pixel are added up to be the brightness for that pixel. It’s not calibrated for any absolute brightness measurement. I hope to incorporate the next spectrometer design into my integrating sphere so that I can make absolute measurements possible (I left an extra port available on my sphere just for this purpose ). Because it’s not calibrated, there isn’t really any unit, just the brightness value returned by the camera for that pixel.
The intensity correction for human perception isn’t done by me, it was done by professionals :P. The webcam itself (and it’s driver) automatically take the sensor readings from the CCD and correct them for human perception (that’s why the picture you see when you use a webcam looks like what you see when you use your eyes). However, it makes me uncomfortable that I’m not the one who calibrated that function, so I’ve been researching ways for calibrating relative brightness readings on a spectrometer and I’ve got a few ideas for how to get that done, but I’m waiting to follow through with that until my next design has been built. And you bring up another good point, even if the webcam’s driver has a perfect correction curve, it’s unlikely that the DVD transmits all wavelengths equally. That’s another reason I want to get a new diffraction grating and calibrate the correction curve myself.
I think I got all your questions, let me know if I missed anything or if you think of any more
Thanks for that link BG79, I’ve been looking for something better than DVD’s since I got into my RGBW stuff. Because of the curved lines it didn’t work very well at all with a multi emitter light and even suffers with am XML color. I had started wondering about a prism but for so cheap I grabbed a few of these things.
Did you have any issue at a with th SA04 from the dual emitters casting light slightly out of alignment? When I did mine it was a little bit off but not like my TK45 RGB, I was able to stick a piece of diffuser film on the lens and take care of it totally.
I did end up getting a usable image for the TK45 but I had to go crazy with the setup, 2 layers of diffuser film (one on each lens, one single piece suspended in front of the lght) and bounce that off a white wall with the camera/DVD around the corner (a piece of cardboard) and then I got a very dim image but still worked, I feel this way was more percise with each individual line being much narrower than when shining the light directly at the DVD.
I take it you mean the SA04 casting light out of alignment for the spectrometer reading? No, that wasn’t really an issue for me. I suppose if I oriented the emitters parallel to the lines on the grating then there would have been some error due to the top emitter being stronger higher up on the band and vice versa, but I oriented them perpendicular to my grating. The narrow slit takes care of the rest, combined with setting up the light pretty far from the apparatus. And you’re right, having some diffuse surface to bounce the light off can soften it a lot and help you get better readings, though you have to use the same wall every time if you want to compare spectra
Thanks for all the answers BM, that explains a lot :-) . The grating slide looks useful!
The only thing that I do not understand is that you say that a webcam corrects for the human eye sensitivity, so that we can see the image correctly. If it does that, the image when we look at it is 'filtered' twice, first by the software, then by our eyes. What in my understanding the camera+display should do is reproduce reality (without correction) as well as possible so that we see as little difference as possible between image and reality.