I picked up a second grain focuser (by Thomas Instrument) recently and compared it to my old Accura model that I have used for years. See photo. I discovered they do not agree, the Thomas Instrument is more accurate when enlarging at full aperture (2-1/4 sq negative at 11 x 14 print size, Nikor lens at f5.6). The print is noticeably sharper. Are these focusers adjustable? How? Thanks in advance.