Selection of microscope objectives: Achromatic vs. Apochromatic, image examples

When buying a new microscope system, it may be difficult to make decisions about the different grade of objective lenses to utilize.  From low end to high end, the prices vary significantly.  Common microscope objective lenses include achromatic, plan achromatic, Fluorite, plan fluorite, apochromatic and plan apochromatic lens.  The main determining factors for choosing lenses includes the number of fluorescence colors you may want to detect, the quality of images required, and the working distance (distance between sample and the lens). 

For the new IRIS Digital Cell Imaging System, three sets of lenses are available:

There is much detailed information regarding the properties of the various lens types. For example, Microscope U has a long article providing detailed descriptions of different objectives.  For users who are choosing between those objectives, theory only goes so far, though.  Above, are examples of the difference in quality of images obtained by apochromatic and achromatic lenses.   The images were taken with an iRiS Digital Imaging System.  The sample is a pre-stained bovine pulmonary artery epithelial (BPAE) cells slide (Life technologies, F36924).  The two images were taken using a 20x Plan Achromatic lens (Logos Biosystem, I10003) and a 20x Plan Apochromatic lens (Logos Biosystem I10010).  The difference in image quality is quite obvious.  The 20x Apochromatic lens image shows lower background, higher signal and resolution.  One note is that the Apochromatic lens works much closer to the sample slide.  The Apochromatic lens allows more light into the microscope, resulting in lower settings for LED excitation and sensor gains and contributes to the lower background fluorescence noise in the image.  Of course, with Apochromatic lens, the shorter working distance may be negative when working with cell culture vessels with thicker plastic walls.