原價：HK$2200
【IDAS NBZ-ll 濾鏡】
即使在城市光污染下也能捕捉美麗的星雲——IDAS
用於天文攝影的窄帶濾鏡「NBZ II」是一款高性能雙波段濾鏡，可同時透過 Hα (656.3 nm) 和 OIII (500.7 nm) 的波長。
尤其是在城市和郊區的天文攝影中，它能夠顯著降低光污染的影響，同時有效地僅讓主星雲的發射波長通過，從而拍攝出清晰銳利、對比度高的星雲照片。
[特點]
・相容於 Hα 和 OIII 的雙波段設計
・顯著降低光污染和月光的影響
・相容各種相機和望遠鏡直徑（M48 P0.75mm）
・日本製造，高精度玻璃，AR 塗層
[規格]
・螺絲直徑：M48mm
・ 螺距：P0.75mmHmm
・75.0/mm
・75 螺距：P0.75波長範圍內具有高透射率
・想要在光污染嚴重的地區拍攝星雲的人
・想要拍攝 Hα 和 OIII 目標（M42、北美星雲等）的美麗照片的人？
The IDAS NBZ-II is a new dual band nebula booster filter - the successor to the NBZ (NBZex) filter. The FWHM of the NBZ-II is 8nm (+/=0.4nm) at OIII, and *9.5nm (+/-0.4nm) at H-alpha respectively. This has the same anti-Haloing characteristics as the NBZ did. For this product, we will provide a test report of the actually measured optical properties with each individual NBZ-II filter piece we ship.
*We originally designed this value to be 10nm, but after runing some production lots, we have now confirmed that the average is 9.5nm (+/-0.4nm).
Feature:
The transmittance curve of interference filters will naturally shift towards the shorter wave length side against oblique light incidence, and this tendency will be more noticeable as the inncidence angle becomes higher as shown in the following figure.
Some of the competitive 7nm or narrower filters will decrease in transmittance by 50% or more when used in a fast optical system (around F2), while the NBZ-II retains 80% or more of the transmittance under the same conditions.
