I saw the Unihedron SQM (see the link below) and was thinking about that one. Any other suggestions?
Jay, The $120 SQM is the only consumer product that I am aware. I own one and enjoy routinely using it. The only other amateur option that I am aware of that would take all-sky light pollution images similar to those seen at page 30 of the May Edition of Sky & Telescope (and formally featured in this newsgroup by the 'Dark Sky Ranger') is described as follows. It would be more expensive than the SQM's $120 price point. I have not yet implemented it, but it is on my 'to do' list for this summer. The following optical setup can be coupled with any T-mount amateur astronomy camera to make an inexpensive fish-eye lens and to take long-exposure images of 160 deg TFOV down to mag 7 or so: Edmund Optics Micro Video Lens 1.68mmFL (160 TFOV), No IR-Cut Filter M12 thread (Edmund online order) http://www.edmundoptics.com/onlinecatalog/displayproduct.cfm?productID=2196 Edmund M12-to-C adapter with lock nut - $30 http://www.edmundoptics.com/onlinecatalog/displayproduct.cfm?productID=3188 Edmund C-to-T adapter before special local milling Male T-Mount to Female C-Mount Adapter NT58-753 - $39 http://www.edmundoptics.com/onlinecatalog/displayproduct.cfm?productID=1316 Edmund 1.68mm FL lens with custom M12-to-C adapter - $38 http://fisherka.csolutionshosting.net/astronote/atm/AllSkyMeteorSetups/14Met... If you already have a fisheye lens for a DSLR (which usually run $600+ USD) with a B button, you can also use that. Based on my limited understanding of the Dark Sky Ranger activities at the Park Service, initially they were using an all-sky fish-eye lens. More recently, the NPS rangers seem to be using some variant on the JPL special purpose mosasic camera - then one used to produce the famous 3-4 gigabyte image of the Obama inaugural address. See - http://en.wikipedia.org/wiki/Gigapan http://www.gigapansystems.com/ gigapan Epic Pro ($900) http://www.gigapan.org/ http://gigapansystems.com/gigapan-products/gigapan-software/gigapan-stitcher... GigaPanStitch The following are some theoretical possibilities that do not involve fisheye lenses - A consumer version of moasiac mounts has been produced - gigapan Epic Pro ($900). A special purpose mosiac mount is an expensive but attractive technological alternative to a fisheye lens. Essentially you could mount a narrow field DSLR on it with a standard 35 deg TFOV DSLR lens and the mount and its software willhandle stitching an allsky mosaic together. Whether such terresterial photography consumer products will destory the photometry data as part of the mosaic stitching process is unknown. Neither will have that laboratory documented accuracy the Unihedron SQM but have the advantage of producing 2-D celestial dome maps instead of the single point reading of the Unihedron SQM. In my planned test fisheye setup, which will initially use a old DSI Pro II monochrome ($90-$120 on sale), the 160 TFOV lens is used to take an all sky image. Then using software like API4WIN, bright calibration stars (0 to -1 mag) can be used to calibrate the image and to convert each pixel in the image into a magnitude and/or magnitude per square arcsecond values. From there, graphing or math software like Mathematica, MathLab or Maple can be used to produce a density graph. Another possibility would be to mount a DSLR with a standard lens on an ASCOM compatible telescope mount. Then try to use EQMOD-Mosaic - an ASCOM application to take mosaics as the driver software to collect a series of 35 deg deep field exposures. Then use AIP4WIN or other astronomy and imaging software to stitch the images together. Just some ideas. - Kurt P.S. - To the SLAS management - Maybe a proposal to think about for the ZAP grant would be the purchase of a DSLR ($700) and a gigapan Epic Pro ($900) through which SLAS would agree to produce documentation of monthly and annual changes in light pollution over Salt Lake County and to develop that data into a school presentation module on light pollution. Note the list of gigaPan Epic Pro compatible DSLRs - only some DSLRs run in fully automated mode. http://gigapansystems.com/compatible-cameras.html