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Optolong L-eXtreme Light Pollution Dual-Bandpass Narrowband Imaging Filter

Optolong L-eXtreme Light Pollution Dual-Bandpass Narrowband Imaging Filter
Price:  £179.00
List Price:  £199.00
(Inc. 20% VAT)

Product Code:  OPT-L-eXtr-1.25
Brand:  Optolong


The Optolong L-eXtreme filter is a dual-bandpass narrowband filter designed for light polluted skies to maximise the output from your imaging time. It offers even higher contrast than the popular L-eNhance filter due to the narrower bandwidths at both parts of the spectrum, H-alpha and OIII.

Optolong came out with their latest development that offers a more extreme dual-narrowband solution in comparison to their very popular L-eNhance filter. Both the L-eNhance and L-eXtreme are Dual-bandpass filters as they let through the light in two sections (bands), however, to distinguish between the L-eNhance and the latest L-eXtreme filters, we had to rename the L-eNhance to a triple-band filter. Both filters have two bands, but the L-eNhance lets through the light coming from three important emission light sources (H-Alpha, H-Beta, and Oxygen III), whilst the L-eXtreme focuses on two important emission light sources only (H-Alpha and Oxygen III), hence the change of title for the L-eNhance filter.

In the L-eXtreme you have two very narrow bands at 7nm each. The bandwidth of the H-alpha  part is similar in both filters (although it is somewhat narrower in the L-eXtreme), but in the L-eXtreme now we have an extremely narrow band at 7nm for the OIII as well. 

The relentless spread of urbanization and its associated light pollution have become a growing problem for all amateurs and astro photographers. The current solutions to the problem can be expensive and might include the purchase of a monochrome camera, several types of narrowband filters and a filter wheel.

L-eXtreme, similarly to the popular L-eNhance provides an economical and practical solution for amateurs. It is a dual-band pass filter which has been designed for DSLR (digital SLR), colour CMOS and colour CCD cameras. The convenience and cost effectiveness of this filter allows amateurs to image a rich selection of astronomical images, even in bright, heavily light-polluted areas.

Optolong believes the design of our L-exTreme filter is a technical innovation among filters. It effectively isolates the H-Alpha and Oxygen III nebula emission lines whilst blocking out 99.9% of light pollution and achieves a maximum transmission of over 93%. As a result, contrast and signal-to-noise ratio from the nebulosity is maximised. The performance of this filter delivers images that superbly control the impact from light polluted skies.

L-eXtreme Filter Spectrum Curve

According to the characteristics of celestial body emission lines and feature of light pollution span of spectrum, Optolong specially designed and optimized the dual-band L-eXtreme filter in order to retain the prominent color of nebula RGB while blocking out nearly all of the light pollution. Spectrum as shown below:

Substrate: B270 (high quality optical glass)
Thickness: 1.85mm
Tpeak: T>92-93%
Blocking range: 300-1000nm
Blocking depth: light pollution  line blocking >99.9%
Surface quality: 60/40
Transmitted Wavefront RMS: λ/4
Parallelism (arcsec): 30"

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