$Askar FRA500 Quintuplet APO Refractor$

Askar FRA500 Quintuplet APO Refractor

£2,060.00✓ 2 year warranty

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About this product

Model: askar_fra500
Part Number: FRA500

The Askar FRA500 features their FRA- series design with a quintuplet air-spaced fully multicoated “three plus two” Petzval lens combination.

The front lens group consists of three lenses (including two pieces of ED glass) for excellent correction of aberrations. The rear group is composed of two lenses separated by a small space. Together they provide a sharp wide 55mm imaging circle, much larger than the standard 44mm full-frame image circle.

Back-focus design means there is no need to calculate back-focus distance or rummage around for a spacer.

The length of the FRA500 is 452mm when the dew shield is extended and 410mm when it is retracted.

The 3.5" heavy duty focuser with a 1:10 dual-speed mechanism provides critical precise focus adjustment.

Supplied with high quality tube rings with carry handle and a sturdy Losmandy-type mounting plate.

Specifications

Aperture size：90mm
Focal length：500mm
Focal ratio：f/5.6
Objective lens：Quintuplet air-spaced APO (including two ED glass)
Image circle：55mm
Back focus：158mm（from base of M48×0.75 thread on the conical extender to focal plane 85mm（from base of M86×1 thread on the rotator to focal plane）
Total length：452mm（410mm when the dew shield is contracted）
Net weight：4.1kg
Gross weight：5.2kg
Rear-end thread type：M86×1
Conical adapter：M48×0.75