Review: Illuminati Instruments IM-150 light meter and its new app

There were rumours among users that Illuminati Instruments went out of business, but the company is very much alive. Except for its QC (quality control) devices, it released the IM-150 Bluetooth 4.0 light meter and significantly updated its iOS app.

The IM-150 has impressive specs. Its exposure measuring range starts at 1 and ends at 1mio lux, -1EV to 18EV, ISO from 3 to 409,600 and a shutter speed of 1/64,000 to 30 sec. Its colour temperature range measurements are from 1600K to 20,000K. And now, in November 2020, the companion iOS app received a serious upgrade with the added ability to set flash exposure for HSS and a colour balance tab that lets you set either a standard illuminant as a reference or a light that you first set as a reference sample to measure against.

The Illuminati IM-100 and now the IM-150 light meters are very accurate. Colour error is +/-75K for most light sources in the range of 2500K to 7000K — except for the IM-100 which did have a 400K error with lights around 5000K. The luminance accuracy is 5% both ways, which is what typical of most instruments. The device can handle an aperture of f/0.5 to f/144 and a shutter angle of 1 to 358 at frame rates of 1 to 1000 fps (video/film).

These meters also come with all the features that you expect in a more expensive meter, including a jack for a sync cord. When used with a cord, you can trigger the strobes from your smartphone or smartwatch. The meter also supports slave/photocell triggering, so it can be triggered from your lights or on-camera flash.

The app starts in a default mode of continuous monitoring of the ambient light levels, but you can turn that off with one tap.

New features in the iOS app are HSS flash measuring, a simple colour screen for ambient and flash output, a colour balance screen, and an upgraded list of colour gels (Rosco Cine gel and GamColor, and Lee gels) in the colour temperature screen.

From the simple colour screen it is instantly clear what your colour temperature and colour shift is. You can choose to report either a gel number of a Duv value beneath the colour shift slider.

HSS flash measuring is a godsend. It was sorely lacking from the first versions of the iOS app, but now it’s implemented in the best way I can think of. You turn on the Monitor Flash switch and select HSS mode. The app will turn it on but not activate it unless you’ve found a combination of strobe speed and f-number that is, in fact, HSS.

The best new feature, in my opinion, is the colour balance screen. Here you will see an RGB readout of the light thrown on the light meter. You’ll see how much the light differs from the standard illuminant you have selected for each colour channel independently. Now, if you could only use D50 or D65 as your standard to test against, the colour balance screen would have limited use, but it’s cleverer: it gives you an option to measure a light and then turn to another one and measure how much that second light differs from the first per colour channel.

With video (and photo) lights that allow you to tune each colour channel — like many do these days — you can actually match lights accurately with this feature.

Some features are still missing with this new app, though. For example, a flash output graph is not available, nor is the reporting of an EV value or support for the Ansell Adams Zone system. Those, however, are all a matter of the vendor’s assessment of the need for adding these to the app — the meter churns out the data anyway and it’s very accurate at it.

The IM-150 retails at $399, the app is free and exists for iOS and Android devices. To give you an impression, the Sekonic that comes closest in terms of functionality and accuracy is a C-800 and it costs $1599.