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The Pierro Astro ADC

The Pierro Astro ADC measured on an interferometer showed a wave front error of RMS 32nm and 164nm PV over the entire surface including the edges. Measured at the center on a diameter of 8mm (Part commonly used in planetary photography) measurement reached an RMS error of 4.98 nm and 38nm PV. These measurements, made   on a couple of prisms at random, are not established for a single surface, but for the entire system (4 surfaces) and testify to the extreme quality of the components




Optical Aperture


Deviation Angle Edge

Surface Accuracy

Anti-Reflective Coating

Lateral Surface


T2 Male and Female

30x48mm (HxD)

24mm Usable

2 Prisms

2.5 Degrees

1/10 ptv

FMC, 300-700nm

Blackened for improved contrast

High quality fused silica, transmission: 170nm to 2500nm (transmission of prisms also depends on anti-reflection coating)

The Pierro Astro ADC is designed as a precision optical instrument. We feel it offers the best value of any Atmospheric Dispersion Corrector (ADC) on the market.

The body is CNC machined in France from high quality Aluminium. The threads are made to a tolerance of 0.05mm. This ensures that the optical axis is kept straight. Any poor alignment will not be due to our ADC.

The prisms are supplied by a UK company and made from the highest quality fused Silicate. They have a minimum surface precision of 1/10 Lamda with blackened prism edges to preserve contrast. The ADC Mk II prisms have anti-reflective coatings optimised for the 300-700nm range.

Mechanically, the prism rings are made of a high quality premium polymer allowing an operational range of minus 20C to 60C and do not over grip the prisms. They are precisely made so the prisms can rotate freely in the body without the need for any grease or compound which might pollute the optics.

The levers are hard wearing stainless steel with CNC machined polymer tightening caps to preserve your fingers on cold nights.

A 10 degree calibrated ring is also included for easy adjustment of the prisms to the correct position.

In brief, the design and manufacture of the Pierro Astro ADC has been  carried out to a standard not normally associated with products at this price. It represents incredible value and superb optical quality.

We provide a full 2 year guarantee against any defects in workmanship on both optics and mechanics.

The Pierro Astro ADC Mk II is available from selected resellers and costs £329 including VAT. Additional components may be required to attach the ADC to your camera / telescope. Your dealer can advise you which adapters you may need. Alternatively you may contact us directly. We are always happy to help.

An Atmospheric Dispersion Corrector or ADC, is a clever little device which corrects the dispersive effects of the earths atmosphere on light rays. Put simply, when you view a bright object such as a Planet with a telescope, you will often see colour fringing. So a large object like Jupiter may have a red and blue fringe in addition to being distorted.

This is caused by the effect the earths atmosphere has on the light from the object as it passes through it. The atmosphere is basically acting like a lens. This effect changes depending on how high the object is above the horizon. The lower it is the greater the effect.  Because of the UK’s longitude, bright objects like Planets are never that high, so we suffer from the effect more .

An ADC corrects this dispersion effect, allowing you to see and image objects free of these distortions and aberrations. No more waiting for an object to get high enough in the sky for it to offer an acceptable view.  Now you can view it anytime with crystal clear quality.

Find out more about how it works here

Star image with an ADC

Star image without an ADC