Askar FMA135 135mm f/4.5 APO flatfield Telephoto Lens (APCS format)

The FMA135 is a air-spaced 30mm apochromatic f/4.5 triplet with an ED element to minimise chromatic aberration 

And has a focal length of 135mm, the objective lens is optimised  for demanding astronomical applications. The objective is carefully matched to an integrated three-element field flattener that yields flat fields and razor-sharp images with astronomy cameras with APS-C (or smaller) sensors.

The camera side of the FMA135 has  a standard M42x0.75 male thread for attachment to most astronomy cameras or T-rings. The instrument has a 55mm back focus. The top tube ring, which acts as a light/dew shield, includes standard M28.5x0.6 female threads that accept 1.25" astronomical filters. The body of the FMA135 includes a rotatable focuser for precise  focusing.

For straight-through observing with an eyepiece, there's a standard 1.25" adapter that threads onto FMA optical tube. The FMA135 also includes a mounting ring with standard Vixen-style dovetail.

The tube length is 11,3cm. The  weight is 285 g 

Includded is a holder ring with a vixen (finder size) dovetail.

• Aperture: 30mm
• Focal Length: 135mm 
• Focal Ratio: f/4.5
• Objective Type: Air-spaced APO Triplet (including an ED Glass). Sextuplet Refractor for APS Imaging
• Overall Length: 113mm (photographic mode with flattener)
• Weight: 280g
• Rear-end Adapter Type:
  • M42 x 0.75 Thread (for imaging)
  • 1.25" Visual Adapter (for visual use)