Focal plane position: Nominal 150 mm behind standard A&G mounting,
370 mm behind instrument rotator mounting face.
The secondary mirror can be adjusted by mm, giving a focal
plane shift of mm.
Field size: 34 arcmin unvignetted, 50 arcmin with 50% vignetting.
Image quality: For a flat focal plane, 1 arcsec over a 2 arcmin field,
2 arcsec over a 34 arcmin field.
mm, giving a focal
plane shift of 
mm.
1 arcsec over a 2 arcmin field,
2 arcsec over a 34 arcmin field.
, 72 
m arcsec
.