Riccardi 0.75x APO Reducer and Flattener with M63x1 Thread

Riccardi Apo Reducer 0.75x with M63 thread

Massimo Riccardi, well-known optics specialist from Italy, has designed a 3-element 0.75x reducer/flattener for apochromatic refractor telescopes. The corrector is suitable for almost all apochromats with focusers of 2.5" or more. The reducer decreases the focal length by a quarter and corrects the field. Turn your telescope into a fast astrograph!

Telescope and camera connectors:

Connection thread at the telescope side: M63x1 (male)

Connection thread at the camera side: M63x1 (female)

Required working distance (backfocus):

The corrector modifies the focussing point. It wanders towards intrafocal. If the corrector/reducer is screwed to the focuser and not sunken into the drawtube, the refractor has to provide at least 170 mm backfocus.

For focusers with a clear aperture starting at 68 mm, we recommend to put the reducer inside the focuser. We will be glad to offer you a customized adapter. Smaller refractors with a clear aperture less than 68 mm need to get the tube shortened, a service we can also offer.

Working distances from the female M63x1 thread to the camera sensor:

The working distances are empirical values. The date compile by Riccardi are taken into account as well as the experience of our customers.

Triplet-Apo 80 mm f/6: 81 mm

TS Triplet-Apo 90/600 mm: 76.2 mm

TS Triplet-Apo 102/700 mm: 75.6 mm

APM/LZOS Apo 100/800 mm: 74.6 mm

APM/LZOS Apo 106/650 mm: 75.6 mm

TS/APM Apo 107/700 mm: 74.75 mm

Triplet Apo 115 mm f/7: 73.65 mm

TS 125 mm f/7.8 Dublet-Apo: 68 mm

Triplet Apo 130 mm f/6: 73.75 mm

Triplet Apo 130 mm f/7: 73 mm

Triplet Apo 150 mm f/7: 74 mm

APM/TS Dublet Apo 152/1200 mm f/8: 70.4 mm

APM/LZOS Apo 152/1200 mm: 71.4 mm

TEC Apo 140/980 mm: 74 mm

GSO/TS/Astrotec RC-Teleskope: 74 mm

Adaption of the reducer with simultaneous sinking into the focuser

The Riccardi Reducer requires quite a lot of working distance, so that in many cases it is necessary to sink it into the focuser tube. For this you need the TS adapter # RiredM63-M68. The adaptation goes as follows:

Screw the reducer with the M63x1 female thread on the camera side to the thread on the adapter.

Then you can screw the reducer with the adapter into the M68x1 female thread of the extension tube or into the transition adapter.

To sink the reducer for example into the focuser of the Skywatcher Esprit Apos, you need the adapter from the M86 male thread to the M68x1 female thread # M68M86N.