William Optics Apochromatic refractor AP 91/540 Red OTA

Description:

The Fluorostar has a three-lens air-gap objective using the FPL-53 ED custom glass from Ohara, Japan, and glass made of lanthanum. This extremely high-quality triplet design provides color purity and sharpness that leaves nothing to be desired - a true high-end instrument!

Combine this apochromat with an appropriately high-quality zenith mirror from William Optics, and you can see stars with a pinpoint clarity that few other optics can provide. Double stars separate clearly and sharply, the bright bands and zones on Jupiter show startling detail, and Saturn's rings stand out as if you were flying past them in a spaceship.

With its large aperture without any obstruction from secondary mirrors, as is necessary with reflectors, the wide world of Messier objects and also much more challenging deep sky objects is open to you. Once you have looked through such a high-quality apochromat, you will be lost in the vastness of space forever!

For astrophotography, the large image circle provides illumination even for full-frame cameras. Combined with the Flat6AIII flattener from William Optics, the result is a faster focal ratio and a leveled field of view all the way to the edge. You can screw the flattener firmly onto the focuser.

The focuser has a smooth, precise 1:10 reduction, a temperature indicator, and a wide range of adjustment. It easily supports heavy astrophotographic equipment, which can also be rotated to set the best position on the sensor.

Another special feature of the William Optics apochromats is the specially channeled focus mask according to Bahtinov:

These new acrylic optical focus masks offer 92% light transmission.

The imprinted pattern provides a diffraction pattern about three times brighter than the classic masks made of metal. The acrylic mask thus shows a clearer diffraction pattern and allows focusing even with the help of fainter stars.

The Strehl value of the FLT91 is 0.95+ and the following cameras can be used for astrophotography:

Canon EF, RF

Nikon F, Z

Sony E

Pentax K

Fuji X

In addition, this high-quality triplet apo is of course also suitable for CMOS and CCD cameras!

The tube has a retractable dew cap and can thus be brought to a comfortable transport size. Furthermore, it weighs with 4.16kg anyway quite little. The FLT91 is therefore also an ideal travel telescope.