telfocus =  158211 Telescope focus
 nfexpo =  7 Number of focus exposures
freference =   17500 Focus value
fdelta =  100 Focus increment
(ra_offset =  0.) RA Offset (arcsec)
(dec_offset =   0.) Declination Offset (arcsec)\n\n# PARAMETERS FOR
(fnrows =   30) Focus number of rows to reverse shift
(refis =  "middle") Reference is first, middle or last ex\nposure?
(focmode =  "auto") Focus mode\n\n# FOR INFORMATION ONLY
(telname =  "ct4m") Telescope name
(station =  "pf") Focal station
(fratio =  "f/2.9") Focal ratio
(platescale =   18.) Plate scale (arseconds/mm)
(mode =  "ql")  

The current telescope focus is stored in telpars (do not change "telfocus" by hand, as it is updated automatically as long as "setfocus" in instrpars is set to "yes" or "auto"), as are the parameters that control how focus sequences are taken. Depending on the seeing, you may want to change the focus step ("fdelta") between successive exposures in a focus sequence, or the number of focus exposures in a sequence ("nfexpo"). The values listed above are good all-purpose values.

Updated on May 10, 2021, 11:05 am