The 1.25" Deep Sky is Lumicon's most
popular nebula filter. It blocks all high & low pressure mercury
and sodium vapor lamp light, neon lights and airglow, while
transmitting the rest of the visible spectrum. Visually, the Deep Sky
Filter enhances contrast of nebula under both light-polluted and dark
skies. The Deep Sky Filter also passes infrared light, making it an
excellent filter for photographing deep space objects through
light-polluted skies. Recommended for telescopes 3" in aperture and
larger.
To ensure that your Lumicon filter remains the World's Best, the
strictest quality control standards are employed throughout the
production process. Each Lumicon Deep Sky Filter is individually
inspected and proudly inscribed with the percentage of light
transmittance of the H-Alpha, H-Beta and OIII emission lines.
The Deep Sky , Hydrogen-Beta , Oxygen
III , and Ultra High Contrast Filters are the result of 20 years of
steady design improvements, and continue to deliver the highest
performance of all anti-light pollution filters obtainable today. The
following information recommends which filter to use on which celestial
objects, and explains how filter transmissions differ.
Objects
|
Examples
|
Best Filter for Viewing
|
Best Filter for Photography
|
Stars & Star Clusters
|
M13, M11
|
None
|
Deep Sky
|
Diffuse Nebulae
|
Lagoon, Swan
|
OIII (light polluted sky) Deep Sky, UHC (dark sky)
|
Deep Sky
|
Planetary Nebulae
|
Dumbbell, Ring
|
OIII (light polluted sky) Deep Sky, UHC (dark sky)
|
Deep Sky
|
Faint Planetary Nebulae
|
NGC 7293, Abell 33, Jones 1
|
OIII
|
Deep Sky
|
Reflection Nebulae
|
Pleiades, Trifid
|
Deep Sky
|
Deep Sky
|
Spiral Galaxies
|
M33, M101
|
None
|
Deep Sky
|
Faint Nebulae
|
Veil, Rosette, N. American
|
OIII (light polluted sky) Deep Sky, UHC (dark sky)
|
Deep Sky
|
Extremely Faint Nebulae
|
California, Horsehead
|
H-Beta
|
Night-Sky H-Alpha
Deep Sky
|
Deep Sky Filter
•
|
Intended for viewing nebulae from light-polluted skies.
|
•
|
Blocks all mercury vapor and high & low pressure sodium
vapor lamp light, neon lights and airglow, while transmitting the rest
of the visible spectrum.
|
•
|
The best all-around visual light pollution filter for use in
urban skies.
|
•
|
This filter also provides high-contrast views of the Martian
polar caps
|
Exit Pupil
Specifications:
The exit pupil of a telescope is a
measure of specific magnification, which differs from absolute
magnification, and which determines the surface brightness of an
extended object image. Exit pupil diameter may be expressed as the
quotient of eyepiece focal length divided by the telescope's focal
ratio. For example, a 32mm eyepiece used on an f/10 telescope will have
a 3.2mm exit pupil. Each Lumicon filter has an optimum eyepiece exit
pupil range shown below.
Filter Type
|
Deep Sky
|
UHC
|
OIII
|
H-Beta
|
Bandpass
|
|
|
|
|
Optimum Exit Pupil (Light-polluted sky)
|
|
|
|
|
Optimum Exit Pupil (Dark sky)
|
|
|
|
|
Notice:
As filter bandpass decreases, optimum
exit pupil size tends to increase. To determine the best eyepiece focal
length to use with a given filter, simply multiply the Exit Pupil value
shown above by your telescope's focal ratio. For example, if you are
using the Lumicon H-Beta filter at a dark site and your telescope has
an f/6 focal ratio, the best range of eyepiece focal lengths to use
with this filter is [(4 to 7) x 6] = 24mm to 42mm.
Filter Construction:
Lumicon nebula filters are made using
thin-film dielectric coatings on optically flat glass. These
exclusively designed dielectric coatings consist of over 30 alternating
layers of several different materials. Each layer is about a wavelength
of light thick and has a thickness accurate to 2 - 3 angstroms. Lumicon
nebula filters include anti-reflection coatings on both sides to
prevent ghosting and increase light transmittance. They also have a
hard, electron-beam deposited coating for mechanical protection. While
still delicate, Lumicon filters may be carefully cleaned with isopropyl
alcohol, or Lumicon’s Advanced Cleaning Kit.
Mechanical Design:
These filters thread directly into most
eyepieces and telescope accessories. Threads are standard for 1.25"
filters. 48mm filters are standard for 2" O.D. eyepieces.
Bandpass:
These Lumicon filters reject man-made
and natural light pollution. Mercury light pollution occurs at 365,
405, 436, 546, 577, and 617nm. High-pressure sodium streetlights emit
at 570, 583, 600, and 617nm. Natural airglow occurs at 558 and more
weakly at 630nm. There is a window of greatly reduced light pollution
from 440nm (blue) to 540nm (green). The Lumicon Deep Sky Filter has a
wide 90-100nm bandpass for most of this range (441-535nm) to yield
maximum transmission of light from stars and galaxies. The UHC Filter
has a narrow 22nm bandpass through 484-506nm. The OIII Filter has a
very narrow 11nm bandpass for 495-501nm, and the H-beta Filter has the
narrowest bandpass of all - only 8nm centered at 486nm. The narrower
the bandpass, the higher the rejection of light pollution and the
blacker the skies. However, a narrower bandpass also means fainter star
images. Nevertheless, the Deep Sky Filter has high transmission for the
photographic red nebula emission lines.
Nebula Emission Lines:
The main visible radiation from
emission nebulae consists of doubly ionized oxygen near the wavelength
of 500nm. There is also weaker emission due to hydrogen-beta at 486nm.
The invisible but photographically important emission of red
hydrogen-alpha and ionized nitrogen occur near 657nm.
Ši prekė į katalogą buvo įtraukta Penktadienis 04 rugsėjo, 2009.