William Optics Apochromatic refractor AP 91/448 Cat 91 Series WIFD OTA

Description

The AP 91/448 optics are an impressive combination of compact dimensions, relatively low price and outstanding optical quality, and are aimed at all astrophotographers and nature photographers. At the heart of the optical design is the Petzval design consisting of 4 elements in 3 groups, using FPL53 and FPL51 glass. The result is a colour-pure, corrected image field with a diameter of over 55 millimetres – making it suitable for full-frame cameras! The fast aperture ratio of f/4.9 allows for short exposure times.

An M48 and M54 thread is provided for connecting the camera. Two suitable adaptors are already included in the scope of delivery. Focusing is helical, i.e. by turning the easy-grip ring on the tube. This means that even heavy cameras are no problem. The telescope has a "WIFD" design, which stands for "with internal focus design". Focusing via the helical ring is therefore internal.

The included prism rail offers two connection options: for screwing with a photo thread, via Arca-Swiss mounting or for insertion into a prism clamp according to Losmandy standard. With these options, it should be no problem to attach the telescope to all common photo tripods, camera mounts or astronomical mounts.

The scope comes with a protective nylon carrying bag and a specially designed Bahtinov mask. This mask helps with focusing and is permanently integrated into the lens attachment.

Optics such as the Cat 91 are ideal for photographers who are dedicated to the night sky, but also to animal photography. With the Cat 91, you not only get impressive optical performance, but you can also enjoy the durable and beautiful finish of William Optics.

It not only matters which telescope you buy but also where you buy it. Our additional services:

We are a leading telescope dealer and know the devices we sell. Our customer service team will gladly help you after your purchase if you have problems with assembly or operation.

We provide a copy of the 80-page Telescope ABC beginners handbook with every telescope.

Specification