Optolong 21 mm unmounted L-Pro filter broadband nebula filter for CMOS cameras

Optolong L-Pro Broadband Nebula Filter

This filter enables astrophotography even from close to the city and brings best possible results. Optolong L-Pro nebula filters cause a significant increase in contrast and allow about a factor of 3 longer exposure times with DSLR, color and MONO astro cameras.

The filter offers a better color balance than comparable filters with DSLR and also with the modern one-shot color cameras with CMOS sensors, such as those offered by ZWO. Of course, the filter also brings a significant improvement with MONO cameras, for example in luminance capture.

Increase of exposure time - factor 3

The exposure time can be extended by a factor of about 3. That means you can expose about 3x longer than without filter before the sky background becomes visible. The light of the nebulae, on the other hand, is passed through almost unhindered. This increases the contrast significantly and even from the vicinity of cities nebulae can be photographed, which are otherwise not within the photographic range of the telescope. Even with galaxies and star clusters, the filter brings a significant increase.

Coating properties:

The coatings are not cemented to the optical substrate, but are applied by electron beam evaporation followed by ion beam assisted deposition (IBAD process). This special process provides extreme durability and scratch resistance as well as high constancy of the central wavelength (CWL) and prevents temperature drift. In addition, there is high transmission in the passband and high optical density in the stopband.

Which side of the filter needs to face towards the telescope?

Optolong has a good explanation on their page with a check on unmounted filters. With mounted filters, it´s easy. The side with the external thread must face the camera.

Link to iOptron page: Should Optolong filters be installed in a certain orientation? (external link)
You can download the generated PDF from our own server.