Focal plane position : Nominal 125 mm behind instrument rotator face
(no A&G unit available). Adjustable from 45 mm to 206 mm.
Field size : 90 arcmin field unvignetted, 93 arcmin with 50% vignetting.
Image quality : At nominal focus, 0.5 arcsec on axis, 1 arcsec
at edge of 90 arcmin field. With focal plane shifted by 50 mm, 1 arcsec on
axis, 3 arcsec at edge of field.
Image scale : 25.6 arcsec mm, 39 m arcsec.
The JKT f/8.06 focus is not normally offered to users, and requirement
for this focus should be discussed well in advance with the JKT telescope
manager.