The B490 is our hardest-working go-to microscope. The top choice for veterinarians, breeders, and clinics, this instrument has proven reliability and optical quality. It boasts features such as a compensation-free Siedentopf head, smooth stage translation, and a precision focus system with easy tension-adjustment and vertical-lock. This darkfield microscope provides enhanced contrast at low and intermediate magnifications. High quality optics and precision mechanics have made this time-tested design a favorite for labs across many industries. Specialized darkfield optics allow you to observe live cells including blood and other fluids. To customize the microscope to your viewing comfort, the eyepiece spacing can be easily adjusted using a precision Siedentopf mechanism. A diopter is available on both ocular tubes to compensate for asymmetry, and the ocular tubes are angled at 30° to comfortably accommodate a seated position without neck strain. The objective turret provides instant access to 4 magnification levels to easily focus in on minute details from 40X to 1000X. Additional 20X eyepieces expand the maximum magnification to 2000X with 8 unique levels. This covers magnifications needed for studying hair follicles, cells, and bacteria. These high-quality lenses are achromatically corrected to improve resolution and color accuracy. The 2-layer mechanical stage provides smooth and precise movement for examination of specimen slides. The stage's low-position controls are conveniently placed near the coaxial focus knobs for a streamlined workflow. Examining specimen slides is intuitive and precise for users at any skill level. The halogen sub-stage lighting provides bright illumination with excellent color rendering. The warm lighting is better suited for prolonged use, causing less eyestrain than LED and fluorescent lighting. The Abbe light condenser has a high 1.25 numerical aperture for oil-immersion, and an iris diaphragm to optimize contrast and depth-of-field. The condenser holder uses rack-and-pinion movement for precise height adjustment. A dry darkfield condenser is included for darkfield observation using the 40X objective lens or lower. With a 0.9 numerical aperture, the condenser works with non-immersion lenses. Two centering screws allow you to properly center the condenser for optimal contrast. Darkfield observation will provide contrast in otherwise indistinguishable objects by highlighting changes in refractive index. This is particularly useful for observing live cells including blood analysis. Specifications Optical System: Finite-conjugate Mechanical Tube Length: 160mm Head: Binocular, 30° incline, 360° rotatable Interpupillary Adjustment: Siedentopf compensation-free gemel Ocular Diameter: 23mm Eyepieces: 10X, 20X Objective Lenses: DIN standard Objective Parfocal Distance: 45mm Objective Mounting Thread: RMS 20.32mm Objective Turret: quadruple Focusing System: Coaxial coarse and fine focus, upper limit-stop, tension control Focus Range: 30mm Division of Fine Focus: 0.002mm Stage Design: Double-layer with caliper Stage Dimensions: 140mm x 140mm X-Y Translation Range: 75mm x 45mm Transmitted Illumination: 20W halogen Condenser: Abbe condenser with iris diaphragm, NA1.25, NA0.7-0.9 dry darkfield condenser with centering knobs Sub-stage Condenser-holder: rack and pinion Power: 110VAC 60Hz Packing List:One binocular head One microscope body Four objective lenses: 4X, 10X, 40X, 100X One pair 10X eyepiecesOne pair 20X eyepieces One dry darkfield condenser One power cord (US and Canada standard) One dust cover Three color filters (blue, green, yellow) One spare halogen bulb One spare fuse One sample bottle of immersion oil