IFW Filters

Optec can supply a full range of filters for the IFW wheel. Filters are easily and safely mounted in the new IFW filter wheel by use of delrin plastic holding tabs and spacers. Filters from 1 to 5 mm in thickness can be accommodated with use of delrin ring spacers. Because the flexible tab and not the head of the screw holds the filter in place, it is impossible for the filter to be damaged by excess over tightening. An ample supple of tabs and spacers are supplied with each filter wheel.

Filter wheels for both 50mm diameter and 2-inch diameter are available. For special purposes, an 8 position wheel configured for 1-inch filters is offered.

Colored Glass Filters

A full range of Wratten numbered filters are avaialble for monochromatic contrast enhancement for visual and imaging applications. These filters are photographic quality and 2mm thick by 50mm diameter. Click here for more information about colored glass filters.

LRGB plus narrow band H-Alpha Filters and OIII

Optec offers an exclusive set of parfocal wide band LRGB and narrow band H-Alpha and OIII intended for CCD astro-imaging. These filters are 2mm thick, 50mm diameter and are made to the highest standards for high transmission and minimum wavefront distortion. The unique construction with the hard dielectric layers placed on only one side of the filter substrate avoids multiple reflections between the two sides found in most filters of this type. Halos and ghost stellar images are avoided.

They are made exclusively for Optec and are not available elsewhere. The wideband LRGB set is similar in transmission to the Astrodon but much less expensive. Our popular Optec LRGB + H-Alpha set is very competitively priced at $690.00 for all five filters.

Our narrow band filters are centered on the H-alpha (656.3 nm) and OIII (500.7nm) emission lines and have a pass band of 8+/- 1.5 nm. Peak transmission is above 85%. All filters in this group are parfocal.

Bessell UBVRI Filters in 50 mm and 25.4 mm diameter

Commonly refered to as Bessell UBVRI filter set, these filters are primarily intended for photometric measurements of stellar objects using a standard color system. They are 5mm thick, 50mm in diameter and have hard AR broad band coatings on both sides. Gerald Persha, owner of Optec, has written a white paper about the subject of filter standards for CCD photometry. These filters are also available in 1-inch diameter and mounted for insertion into the popular CFW filter wheel from SBIG.Click here to learn more. A clear filter to maintain parfocality is also available in both sizes. In 1990, Dr. M. S. Bessell published a detail description of these filters as used in CCD photometry. Click here to retrieve the original paper.

Marco Lorenzi from Italy uses the Optec LRGB, H-alpha and OIII filters with his STL-11KC2 camera. Click on his logo below to see the results of his work.