Zeiss Standard 25 ICS Operating Manual

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Zeiss Standard 25 ICS Operating Manual Manual pdf 14 page image

Standard 25 ICS1-6 B 40-029 e 01/981.4 ObjectivesThe objectives are the optical centerpiece of the microscope. The following is an example of howobjectives can be labelled:CP ACHROMAT 10x/0.25 /-where10x = objective magnification, with a defined color ring on the objective being allocated to eachmagnification step (Zeiss color code)0.25 = numerical aperture = infinite tube length- : can be used with cover slip thickness D = 0 or 0.17or0.17 = can be used with cover slip thickness D = 0.17andOil = oil immersion objectivePh 2 = phase contrast objective with a green color ring and phase stop Ph 2The objective magnification multiplied by the eyepiece magnification (minimum 10x) results in the visualoverall magnification, e.g. 10 x 10 = 100x.The numerical aperture x 1000, e.g. 0.25x1000 = 250x, is the highest useful magnification, i.e. nofurther details are resolved above that limit.The objective labeling indicates that these objectives may only be used with microscopesfeaturing an infinite tube length and not with instruments the objectives of which are markedwith "160" as their mechanical tube length.The exact observance of the cover slip thickness of 0.17 mm is all the more necessary the higher thenumeric aperture of the objective. Therefore, so-called "Corr" objectives can be set for different coverslip thicknesses via a correction ring. For this, a specimen area is searched, and the position of thecorrection ring where optimum focus and image contrast are obtained is determined (refocusing isalways required).Immersion objectives are always insensitive to differences in cover slip thickness.When immersion objectives are used, the air between the cover slip and the objective is replaced with aliquid, which is immersion oil in most cases. The plastic oiler containing 20 ml of 581 N immersion oil isparticularly suitable for this purpose.Due to their short working distance, objectives 25x and higher feature resilient mounts (specimenprotection). To prevent oil contamination of the specimen when the nosepiece is turned, the resilientmounts of the immersion objectives can be locked in their lifted position by turning them to the right (donot forget to unlock them again!).