Test of IDAS (Previously known as Tokai) Light Pollution Suppression Filter

The new IDAS Light Pollution Suppression filter appears to be a breakthrough for astrophotography.  Additional OEM information is available here.  The following tests were made using the 48mm LPS filter and AP 130mm F/6 on Kodak E200 film:


Raw Scans from the SprintScan35+ scanner:

Normal PhotoShop processing of the raw scans:

Close-up view of the center area:

Test Notes


AP-130 F/6  and AP Field Flattener.
AP 600 GoTo Mount with ST-4
Film & Exposure: Kodak E200 Slide:  36 mins for No Filter,  50 mins for IDAS Filter
Location: My Driveway (Huntertown, IN),   Moderate Light Pollution
Date: Nov 13, 1999
Notes Unlike previous light pollution suppression filters, the IDAS maintains a much better color balance by notching only around the individual spectral lines of the typical mercury and sodium vapor lights.   Other filters like the Lumicon Deep Sky have an overpowering magenta cast; the IDAS does not.

An equivalent level of processing was done on each image to reach a common point of graininess as shown in the close-up images.  This should provide a good comparison of the maximum quality possible with and without the filter.

I believe that the above image could have been exposed for 70 mins with the IDAS Filter so additional improvement can be expected.  Overall, the filter appears to improve the image quality by at least a factor of two.  Very impressive!

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