APM CNC-LW II 203/1420 Refractor OTA

Description

At 203mm, this is the largest aperture in the CNC-LW II line, and the numbers show it: 0.57-arcsecond resolving power and a limiting magnitude of 13.5, both the sharpest in the series. The APM CNC-LW II 203/1420 is built for observers who have outgrown smaller apertures and want research-grade resolution without switching to a reflector’s central obstruction.

This OTA ships without a mount or tripod, and at 24.0kg it’s the heaviest tube in the line — plan on an equatorial mount rated for at least 45kg once a full imaging train is attached. That weight buys real capability: an 8-inch apochromatic triplet resolves detail that smaller apertures in this series simply can’t reach, on both planetary targets and faint deep-sky objects.

Key Features of APM CNC-LW II 203/1420 Refractor OTA

An 8-inch, 3-element air-spaced Super ED triplet with 99.6% per-surface transmission scales up the same optical formula used across this line to its largest aperture yet.

• 203mm apochromatic triplet resolves fine detail that smaller apertures in this series can’t reach
• 0.57-arcsecond resolving power is the sharpest in the CNC-LW II line
• Limiting magnitude of 13.5 pulls in fainter deep-sky targets than the smaller models in this series
• Starlight Instruments Feathertouch dual-speed focuser holds precise focus under the extra weight of a full imaging train
• 60mm image circle keeps medium-format sensors fully illuminated at this larger aperture
• Retractable dew shield protects the largest front element in the line through long sessions
• Heavy-duty flight case is built to transport a tube this size without stressing the optical cell
• Magnification range extends to 400x, the highest useful ceiling in this series

What Sets the APM CNC-LW II 203/1420 Apart

Stepping up to 203mm from the 175mm or 180mm models in this line isn’t a small jump — the extra aperture and the resulting 0.57-arcsecond resolving power put this tube in research-grade territory, closer to what a small observatory would run than what most backyard setups carry. The trade-off is real: a 24kg tube and a 45kg mount requirement mean this isn’t a scope you relocate between sessions, so a permanent pier setup suits it better than a portable rig.

Applications & Use Cases

Built for research-grade observatory astrophotography, this refractor handles uncompromising high-resolution lunar, planetary, and deep-sky imaging across large-format sensors.

• Serious observatories or advanced amateurs running a fixed pier setup rather than a portable rig
• Imagers who’ve maxed out the resolving power of a smaller APO and need the largest aperture in this line

APM Warranty & Support

The CNC-LW II 203/1420 carries a 2-Year Factory Warranty covering manufacturing defects on the optical tube and focuser assembly, handled directly through APM’s support channel.