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Meade Nebular Filter (Broadband) Series 4000 for SCT rear cell - 911B #07524 

This item is in the original box no paperwork - It is only for Schmidt Cassegrain Telescopes! It will not fit any eyepieces or diagonals or other types of telescopes, it is intended to be threaded directly on the rear cell of the SCT telescope. Really nice for either visual or astrophotography to enhance the Ha, O-III and S-II bands while reducing light pollution "skyglow" creating a much enhanced view and more contrast detail in most nebulas.

For dramatic increase in visual and photographic detail in deep-space emission and reflection nebulae. I note only a tiny mark on the metal cell which does not affect the optics in any way. This was a display item in the case at the telescope shop I worked in, never used on a scope. Retail cost was $129.95 now out of production.

Meade Series 4000 Nebular Filters incorporate the very latest in interference coatings technology. Each filter includes more than 40 coating layers to reject, with precision, unwanted light from urban light pollution while passing critical nebular emissions with minimal reduction. 

Technical Basis of the Meade Broadband Nebular Filter: As shown in the transmission graph below, the Meade Broadband Nebular Filter strongly rejects the light of sodium- and mercury-vapor lights as well as natural airglow and auroral emissions. Conversely, the strong nebular emission spectral lines, transmitting in the visually sensitive regions primarily at 486nm (Hydrogen Beta, or Hß) and 496 to 501nm (Oxygen-III, or OIII), are passed through the filter with high transmission percentages. The effect of the filter is that nebular light reaching the eye is observed visually in dramatically increased detail, while the effects of unwanted city lights are greatly reduced. The Meade Broadband Filter also passes photographically-important Hydrogen Alpha  nebular light at 656nm largely unattenuated, making the filter a valuable aid in the photography of deep-space emission nebulae as well. The contrast between galaxies and the night-sky backdrop is also typically enhanced by the filter, but because galaxies emit light in a much broader range of wavelengths than nebulae, the effect is generally not as dramatic in these cases.  

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