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The L-eXtreme is a 7nm dual bandpass filter which can be used with one-shot color cameras like DSLRs and CCD/CMOS astrophotography cameras. It's most suited for fast systems or long exposures. The convenience and cost effectiveness of this filter allows amateurs to image emission nebulae even in bright, light-polluted or moonlit skies.
The L-eXtreme isolates the H-Alpha and Oxygen III emission lines so that the contrast and signal-to-noise ratio of a nebulae are maximized. For people who are imaging in very light polluted areas or when the moon is out, the L-eXtreme is an excellent choice.
The advantage of the L-eXtreme filter is that there is no light transmission between the H-beta and OIII lines (as there are no nebula emission lines there). This reduction in light pollution maximizes the nebula's signal and makes the sky background darker while imaging.
Unlike the L-eNhance filter, which is a tri-band filter (it transmits H-Alpha, H-Beta, and O-III), the L-eXtreme filter is dual-band, passing just the H-Alpha and O-III emission lines in order to deliver improved light pollution rejection.
Note: The Optolong L-eXtreme filters (apart from the threaded both sides version) have threads on one side to keep them very thin - 1.85mm not including the threads - they can be used with Filter Wheels, Filter Drawer System, focusers with a place to thread focal reducers internally (such as some Moonlite focusers) and camera nose pieces that fit into compression rings, but the 1.85mm filter should not be threaded into the imaging train like an adapter ring with threads on both sides.
The threaded both sides version however can be used like an adapter ring and can be threaded directly into your optical train without any additional equipment required. The threaded both sides version has a thickness of 7.6mm not including the threads. Note that this size filter will NOT fit in most filter wheels or drawers.
Note: For imaging galaxies and reflection nebulae, the Optolong L-Pro filter is more appropriate as the L-eXtreme and L-eNhance filters will reject much of the light from those broadband or reflection objects.
Manufacturing Technology
Packing
Outer Box: cardboard sleeve box
Inner Plastic Box: Strong PP material
Lining: Imported high pressure white EVA
Substrate: B270
Thickness: 1.85mm
FWHM: O3 7nm+Ha 7nm
Blocking range: 300-1000nm
Blocking depth: light pollution line blocking >99%
Surface quality: 60/40
Transmitted Wavefront RMS: λ/4
Parallelism: 30s
Good morning ( optolong L extreme 7nm ) What is the format ( 2”. ? ) to fit my setup ? Skywatcher evostar 80ed, starfield 0.8 flattener/ reducer , Canon Dslr eos 700 d
Yes for the L-eXtreme you will need to use the 2" filter as there is currently no clip filter available for it (as of June 2021). We would recommend using a filter drawer, assuming you have the available back focus. The ZWO filter drawer consumes about 21mm of back focus: https://telescopescanada.ca/products/zwo-filter-drawer-m42-to-m48?_pos=2&_sid=86d92dd15&_ss=r
As far as I know, you cannot install a filter inside this flattener, but good to check this. If so it would also be the 2" version.
Cheers
Stephen
When are you expecting the L-eXtreme 7nm 2" to be back in-stock?
We expect the L-eXtreme 2" filters to be back in stock sometime in the week of October 26th
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