Sky Quality Meter with Lens - Narrow Field of View SQM-L

Simple to use and works well. The auto-dimming display is an intelligent feature, and I was pleased to find a good quality nine volt battery installed, rather than a no-name one. And the sticker on the back indicates that it's made in Canada rather than China.

The meter comes with a 9V battery to get started. The operation is just the push of a button, with a recommendation to average four readings. A number appears within seconds after the button is pushed, and the unit turns itself off after a minute or so. The optics screen out infrared light, for a true visible light measure.

This items provides a logarithmic sky quality reading in mere seconds, allowing amateur and professional astronomers to quickly assess the transparency of observing sites. The measurements are in magnitude per square arc second with maximum possible darkness being +22.0. For example, a mall-lit suburban site would be 18.0, a moderate transitional sky would be 20.5, a good country sky would be 21.20, a significantly dark sky with scintillating Milky Way would be 21.50, and a deep New Mexico night with the Milky Way looking like real clouds would from 21.95 to a perfect 22.0, Significant telescopic work can be done with amateur instruments having 10 or 12-inches of aperture in skies above 21.0, including observation of galaxies of magnitude +14 and fainter. This particular model is narrow-field, making it more sensitive to where it is being aimed. This makes it easier to choose the region of sky from which the reading is being taken.

Excellent, though the output was saddening. It shows my local skies have an SQM of 18.4.... Light pollution sucks :(

Quality instrument. I use the SQM-L with my telescope. Before, during and after set up, I take a few minutes to use the meter to check the quality of the sky at my location. It does what it is advertised to do. Good construction, no rattles, nice pouch and good instructions. Not a toy. Take some time to preserve the night sky.

Works great - of course depends on where you aim it...even the Milky Way will kick up the readings, so best avoid that direction to get true blank sky background. The narrow field configuration helps that option.

Want to know how dark your various telescope viewing sites are? This device makes it scientific and repeatable. It was easy to compare my home versus various campgrounds. It paid for itself when I was looking for retirement land as well.

It does what its supposed to do. Amazing that when you look into a dark night sky that this device can actually tell you if the seeing conditionsa good or great to do AP on a given night. Having a sky reading of 21 which looks good to the eye is much worse than a reading of 22.5 for AP work.It's solidly built and will also display the temperature in C and F, It is very basic looking but does the job making AP people know when tostart capturing images.