hi aric, the 5 inch jaegers objectives were F5, cemented achromats, and were available coated or uncoated. they were otherwise the same. they were rated by jaegers as astromomical objectives, and can be used with a 6mm eyepiece (approximately 100 power) without image breakdown, or severe color problems except on bright moon features etc. they were advertised mostly for "deep sky "applications, but with a good barlow and good eyepiece, you can have high power fun too. if you want a high performance short focus apo refractor, this is not the one, but it performs well under the conditions that it was designed for. jeagers refractor lenses (the 3.25/4.12/6.00 inch series) were airspaced F15 achromats (the 6 inch were also available in F5/8/10 ) and were of high quality, and were diffraction limited. good luck, tom leech