About this product
Model: idas-dtd-48st2
Part Number: DTD M48ST2
IDAS DTD (Dusk till Dawn) Filter
A new generation filter covering multiple objects including comets, galaxies, the Milky Way, and emission and reflection nebulae, by making use of the extra transmission in the NIR region.
Features
The IDAS DTD filter not only passes the Ha and OIII regions in the same manner as the IDAS NBZ, but also provides a pass band for comet ion tails in the visible spectrum range (400nm to 700nm, susceptible to light pollutions). This filter furthermore enhances the contrast of the continuous spectrum lights from comet dust tails, galaxies and the Milky Way by making use of the NIR region that is hardly interfered by light pollution. The DTD filter makes it possible to shoot more objects in the visible to NIR spectrum range at higher contrasts.
n.b. on halos:
Optical filters such as the IDAS DTD and GNB utilising infrared tend to cause haloing in the NUV and NIR regions. This is because the anti-reflection properties of off-the-shelf cameras' optical systems (optical window and sensor cover glass) are optimised for the visible spectrum only, not for the NIR region. Thus, haloing at the camera end in the unoptimised region becomes more apparent, coupled with haloing from the filter itself.
Here is a rough estimation of the magnitude of haloing where the haloing magnitude of the NBZ Filter is counted as 1:
- DTD + IMX294 sensor results in 7.9 times
- DTD + IMX585 sensor results in 23.7 times
M20 Nebula:
Telescope - Takahashi Epsilon200. Camera - SVBONY SV705C. Exporsure Time - 36x120s. Taken by Mr. Uto in Shizuoka, Japan on March 19, 2023
Filter Thickness 2mm
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