A. About Optolong's L-Pro FIlter
The Optolong L-Pro (L-Professional) broadband filter is designed to improve the visibility of various deep sky objects. It does this by:
- Selectively reducing the transmission of wavelengths of light pollutants, specifically those produced by artificial lighting (including mercury vapor lamps, both high & low pressure sodium vapor lights, and the unwanted natural light caused by neutral oxygen emission in our atmosphere (i.e. skyglow)).
- Being highly transparent to the main nebula emission lines at OIII (496nm and 500nm), H-beta (486nm), NII (654nm and 658nm), H-alpha(656nm) as well as SII (672nm)
Unlike other light pollution filters such as UHC and CLS, the L-Pro is multi-bandpass filter which offers better color balance by maximizing the transmission band. The balanced transmission allows astrophotos to be taken with minimal color cast in broadband emission objects such as galaxies, reflection nebulae and globular star clusters. L-Pro is an excellent choice for light pollution suppression.
B. Main Uses and Performance
- Suitable for enhancing the contrast and details for both visual and photograghic purpose at urban and suburban areas with heavy light pollution.
- Suitable for color CCD cameras and unmodified DSLRs.
- Works well on most emission nebulae, reflection nebulae and dark nebulae.
- L-Pro filter has a very low transmission reduction rate against continuous spectrum space objects, and thus is quite effective in suppressing light pollution sources when shooting galaxies, reflection nebulae and globular star clusters. The same holds true for visual star observations.
C. Spectral Curve Transmission Characteristics
- High transmission of main nebula emission lines:
- H-beta 486.1nm, OIII 495.9nm and 500.7nm, H-alpha 656.3nm, and SII 672nm.
- Precise and high blocking of major transmission lines of artificial light pollution:
- Hg (Mercury) at 435.8nm, 546.1nm, 577nm, and 578.1nm.
- Na (Sodium) at 598nm, 589.6nm, 615.4nm, and 616.1nm.
- It also blocks out infrared wavelengths (700-1100nm) so a separate IR cut-off filter is not required for imaging applications.
D. Technical Specifications
- Both surfaces are fine optically polished, accurate to 1/4 wavelength or better, and parallel to within 30 seconds or arc.
- 2mm thick Schott B270 optical glass substrate material.
- Very high surface quality of 60/40 or better (US Military Spec MIL-O-13830).
E. Optical Coating Specifications
- Multi layer anti-reflection coated.
- Non-cementing optical substrate coating.
- Electron-beam gun evaporation with Ion-assisted deposition coating technology for durability and resistance to scratching, as well as stability on CWL (central wavelength) so that there is no deviation due to temperature changes during use.
- Precise and homogeneous coatings ensure high values of desired passband and blocking of unwanted offband.
- Every single filter is tested and passed by Optolong before shipping to dealers.
- 1.25" astronomy filter with standard M28.5x0.6 male filter thread (no female thread, so it cannot be stacked with other filters).
- Ultra-thin filter cell to minimize vignetting; clear optical aperture of 26mm.
- Precision CNC-machined metal filter cell with sand blasted black anodized finish, anti-reflection treatment, and laser engraving.
- High quality protective plastic storage case.
WARNING: Optolong filters are not designed for direct solar observation. NEVER use these filters for observing the Sun, or permanent eye and equipment damage will result.
Oct 4, 2017
Great filterPros: Cons: Comments:
I purchased the 2 inch Optolong L pro filter a few months ago. It has done a great job of taking care of the many street lights I have around where I take astrophotos. I used to use light shields to block as much of the light as possible. So far I have been able to not use the shields even with a 10 inch ota.
The filter gives a good color balance without a lot of fuss. I have even had to up the gain setting in my camera and used 10 minute exposures.
This is one of the best filters I have used for one shot color shots. I am using the ASI071 camera.
This review was provided courtesy of AgenaAstro.comSep 7, 2017
Optolong L Pro FilterPros: Cons: Comments:
Give wonderful balanced color when used with my Modified DSLR's and significantly reduces LP increase contrast. Excellent filter and I will buy another so both DSLR filter holders will have this installed.
This review was provided courtesy of AgenaAstro.comFeb 8, 2017
Excellent for urban astrophotographyPros: Cons: Comments:
I have evaluated this extensively, and find that the L-PRO make a significant difference in contrast in emission nebulae, and a noticeable difference in contrast in other objects.
This review was provided courtesy of AgenaAstro.comDec 24, 2016
Top quality.,Pros: Cons: Comments:
I own filters from different brands, once I started using the optolong filters, I came to the conclusion that they are very good if not better than other more expensive brands,. Nothing plastic, very well done and the glass is the same one used on the most expensive ones...do not hesitate, buying any of the optolong filters,. If I'm not mistaken,. I already have the whole line of optolong filters, some 1.25 others 2"., thanks Rich
This review was provided courtesy of AgenaAstro.comSort by