Sofirn was so kind to send me a late prototype of their IF25 for testing and for reporting any recommendations what to improve in later batches. Many thanks for that to Sofirn. The IF25 prototype arrived here on 10/25/2019 and I would like to share my initial impressions with you. Further tests like a thermographical analysis of heat transfer and regulation as well as measuring tailcap currents are still pending for I did not have the time to do that yet.
All in all, I'm quite satisfied with the IF25 and can recommend this flashlight to anyone who is interested in a handy and versatile 21700 EDC light with tint ramping. The points of criticism and suggestions for improvement that I have noted below relate mainly to details that could further enhance the user experience and appeal to an even larger group of buyers. As always, I have tried to express my feedback as objectively and unbiasedly as possible.
@ maukka: I tested following scenario for possible conflicts in the UI:
- IF25 set to stepped mode
- IF25 being used for tint ramping (click + hold)
- Immediately, after tint ramping I tested to shut down the IF25. Holding the button was successful and the light went off. Click + hold reversed the tint ramping direction or (after 1.5s) changed the tint in the same direction as before.
- Bottom line: No conflicts in the UI. Still, I would prefer to "click" for ON/OFF and "hold" for mode cycling.
Component | Pros | Cons | Suggestion |
Overall appearance | The workmanship and material quality is as far as possible at a high level. The threads are cleanly manufactured, the optic is free of dust and dirt inclusions and the battery tube is concentrically drilled out. The 21700 format is future-proof and offers high capacities for long runtimes. The IF25 also looks extremely compact and handy. The switch has a good pressure point. The dust protection cap of the USB-C port holds it securely in place. | The cooling fins are sharp-edged and the anodization has small imperfections. This will be fixed in series production. The battery tube of the prototype is firmly glued to the head (probably to protect it against reverse engineering) - it remains to be hoped that the production model does not have a glued battery tube. | The sharp-edged cooling fins should be better deburred. I also recommend to grease the threads slightly (they are dust-dry from factory). A knurling on the battery tube and tailcap would fit the IF25 well to improve tactile handling. |
Beam quality | Due to the small die area of the SST-20, the beam is not too floody. The beam profile is nevertheless quite balanced in throw and flood due to the optics Sofirn used to get a nice hotspot for effective ranges up to approx. 50m while still having plenty of light in front of your feet. Despite "shifted-running" LEDs (in the pure WW/CW settings) the beam on a whitewall is mostly homogeneous and free of deformations or artefacts. The color mixing of 2x CW and 2x WW results in a rather reddish drift from the BBL, instead of going into the yellow-greenish (above the BBL). This effect is usually preferred. | Due to a proprietary optic, no alternative optics with a different beam angle or degree of diffusion can be used. Cold white light (> 5.000K) has a strong tendency to blue - a typical disadvantage of the SST-20 6.500K. The use of 95CRI leads to a disproportion of the power compared to 70CRI LEDs. Warm white light is therefore measurably less bright than cold white light. |
No immediate need for action, but standardised optics such as those from Carclo or Ledil offer more flexibility for customizing the beam profile. For a less bluish light I recommend to use SST-20 5.000K 70CRI with which a relatively clean neutral white can be realized. Alternatively, it would be better to use Samsung LH351D of consistent CRI values to balance the performance gap of the LEDs. However, the beam profile will then become more floody, which could only be influenced by changing the optics. |
Driver and thermal control |
A constant current driver with buck converter is used. This allows a stable power level without the typical FET brightness drop in the voltage curve. Thanks to the buck converter, widely used 2x CR123A primary batteries can also be used for emergencies. Sofirn finally got rid of a timed stepdown. The thermal regulation has also been revised and automatically intervenes in 3 stages (45°C, 55°C, 65°C) to regulate heat generation. |
Unfortunately, a configurable stepdown behavior has been omitted. It would be nice, if Sofirn were to give the user the possibility to change the light's thermal control according to his own wishes, like HaikeLite, Tom E's NarsilM or Toykeepers Andúril offer for quite some time. The regulation seems a little too "aggressive" to me personally, i.e. the IF25 steps down quite far, subsequently cools down more than necessary and thus gives away some potential. |
A configuration menu for changing the stepdown behaviour, which can be reached via e.g. 10x clicks, would be useful. Power users might want to accept a significantly warmer lamp for a longer runtime at higher light levels. Other users may prefer a very moderate heat output and would like the IF25 to remain cooler even more than the factory default. Sofirn's ATR could be somewhat less conservative and allow a warmer, regulated continuous temperature. |
Charging | With USB-C, Sofirn has chosen a format that is future-proof and significantly more failsafe. Gone are the days when you wanted to plug the fiddly microUSB plug into the socket the wrong way round. With an effective 1.7A at 5V there is a reasonable charging current for the 21700 format. The prototype has charged a Samsung 50E battery up to 4.165V, which isn't 100% but on the other hand it will ensure a better battery life expectancy. | ||
User Interface |
Sofirn uses a sophisticated but simple user interface. A short glimpse into the user manual is therefore sufficient. In addition to stepped modes there is also stepless ramping. The light can also be operated at a low light level during charging. Tint Ramping for changing the colour temperature works extremely well and intuitively. |
Unfortunately, Sofirn is not always consistent in defining the UI for stepped modes. While some of their flashlights require the switch to be held in order to cycle through the light levels, the IF25 requires single clicks to be made and the switch to be held down to turn it off. This leads to confusion for the customer, who may has bought several Sofirn lights. |
Most customers prefer "hold to cycle throgh modes" and "click for on/off", as in ramping mode. This is also implemented in the UI of the new SP33 V3. It would be nice if an IF25 V2 also gets this. Unfortunately, the IF25 has no mode memory for Moonlight in ramping mode, i.e. it starts at least at a low mode above moonlight. It would be desirable that the mode memory works to the lowest setting. |