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Archive for May 2022

The new Herschel wedge from APM for solar observation

May 12 2022, Stefan Taube

A Herschel wedge, also known as a Herschel prism, is a special device for observing the Sun. It has many advantages over an objective filter, but can only be used with lens telescopes (refractors).

The manufacturer APM offers a new model with excellent features at a reasonable price: the APM Herschel wedge 2″ with Fast-Lock.

Herschelkeil APM

This Herschel wedge from APM is equipped with a ceramic light trap, an integrated ND3 filter and a replaceable polarising filter. All filters are of course multi-coated! Image brightness can be adjusted by rotating the polarising filter. This means that the Herschel wedge can be used for both visual and photographic purposes!

The APM Herschel wedge is equipped with a quick release (Fast-Lock) eyepiece adapter and an adapter for 1.25″ eyepieces and camera connectors.

Herschelkeil

Using a Herschel prism for solar observing is not only safer, but also qualitatively better than a foil filter. The resulting image is sharp and rich in contrast and can therefore be enlarged to a higher degree.

The Herschel wedge can only be used on refractors with an aperture of up to 150mm.

The new apos from Skywatcher: Evolux 62ED and Evolux 82ED

May 5 2022, Stefan Taube

The trend towards astrophotography with small but high-quality refractors is continuing. These lightweight apos do not need an expensive mount, are easy to transport and provide fantastic images of wide areas of the night sky.

With the new Evolux series, Skywatcher offers two new models in this segment:

AP 62/400

Compact and proficient: the Skywatcher Apochromatic Refractor AP 62/400 Evolux 62ED

Evolux telescopes are perfect wide-field instruments and are therefore ideal for observing and photographing large areas of the night sky. The doublet lens consists of a combination of optical glass, including a low-dispersion ED glass element, which provides sharp images of stars with high contrast and no visible chromatic aberration.

All lens elements are coated with Skywatcher’s sophisticated metallic high-transmission coating (MHTC™), one of the highest quality multilayer coatings in its class, which allows up to 99.5% light transmission.

Evolux telescopes are supplied in a foam-lined aluminium case and are equipped with a 2.4″ dual-speed rack and pinion focuser, together with a tube clamp with a Vixen-style prism rail. The dew shield can be retracted for easy transportation.

The appropriate field flattener should be used for photography: Flattener 0.9x Evolux-62ED and Flattener 0.9x Evolux-82ED. These optical aids ensure sharp star images even at the edges of the field of view and reduce the focal length, so that the Evolux becomes a fast and corrected telescope for astrophotography.