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Natural Science Forum / Physics / Optics / June 2005Several condensor questions
First: On my Zeiss Standard I have some high-NA planapochromates. The condensor has a NA of 0,9. Would the quality of my image improve much with a condenser that has a higher NA? If so: which condenser should I get? Second I'm experimenting with using my Zeiss objectives and eyepieces on a Nikon microscope (both tubus length 160mm). So far the results are fine. I've read (and found out by experimenting) that you shouldn't mix eyepieces and objectives of different brands, but can you mix condensers? What I mean is: does the Nikon condenser give worse results than my Zeiss condenser? Third If a condenser has a NA of 0.9, is it useful at all to have objectives with NA higher than 0.9? Fourth Is it necessary for NA greater than 1.0 to use immersion oil on both sides of the object glass? I've read this here (Zeiss): http://www.zeiss.com/4125681F004CA025/Contents-Frame/7CB1519D8BF1BF4CC1256B760026F0FE Fifth If the previous is true: many objectives have a NA higher than 1.0, but does anybody ever use immersion oil between object and condenser?? Theo 1) From http://www.microscopy-uk.org.uk/mag/artmar04/godarkfield.html, the limit of resolving power for a compound microscope is given as d[µm] = 1.22 lambda[µm] / (NA_Condenser + NA_Objective) Hence, this will depend on what high-NA planapos you are talking about. 2) Don't! Espcially, don't waste your time with this if you plan on using oclulars from Nikons CF and CFI60 system. Make a google search for "Chromatic Difference in Magnification" (CDM). 3) Yes! See point 1 above. 4) No. This only applies if there is no specimen in the optical path and you just want to illuminate the entire backfocal plane of the objective. Otherwise, diffraction in the specimen plane "boosts" the resolution capability of your setup (see equation in point 1 above). 5) Clear since previous point is not true. Gregor Gregor, Thanks for your answers. My situation is that I already had a Zeiss standard and bought, over the years, some planapo's. Recently I bought a Nikon photomicroscope and I like it very much. For microphotography (or photomicrography, whatever you want) it is great. So I tried my Zeiss objectives in it and got bad results. Then I tried my Zeiss objectives plus Zeiss Kpl eyepieces and got good results. Obviously objectives and eyepieces of a specific brand and type are matched. But are the condensors matched, too? Is the illumination from a Zeiss standard the same as the illumination of my Nikon? I also read about high-NA aplanatic and/or achromatic condensors. Will these give better results (apart from the fact that I never saw one for sale ...)? Are they difficult to use? Theo 1) From http://www.microscopy-uk.org.uk/mag/artmar04/godarkfield.html, the limit of resolving power for a compound microscope is given as d[µm] = 1.22 lambda[µm] / (NA_Condenser + NA_Objective) Hence, this will depend on what high-NA planapos you are talking about. 2) Don't! Espcially, don't waste your time with this if you plan on using oclulars from Nikons CF and CFI60 system. Make a google search for "Chromatic Difference in Magnification" (CDM). 3) Yes! See point 1 above. 4) No. This only applies if there is no specimen in the optical path and you just want to illuminate the entire backfocal plane of the objective. Otherwise, diffraction in the specimen plane "boosts" the resolution capability of your setup (see equation in point 1 above). 5) Clear since previous point is not true. Gregor Theo: This will depend on your application whether you should use an aplanatic high-NA condenser (with NA 1.4). For my work, I usually use an Achromatic condenser (dry) with swing-out top at NA 0.9. It works great for most of my brightfield work. For oil, I still use a simple Abbe top with NA 1.25. Mixing condensers can be tricky. For instance, the better condensers for the Nikon E400 will not allow you proper Koehler illumination on a Nikon E200. The phase condenser from a Nikon system does not work on a Leitz Ortholux. You have to be very careful when mixing components. Especially when you want decent Koehler illumination for your work. Gregor > Gregor, > [quoted text clipped - 13 lines] > give better results (apart from the fact that I never saw one for sale ...)? > Are they difficult to use? Hi Theo, As you have discovered older Zeiss objectives have part of the correction built in the Eyepiece. The same is true below the stage all the parts need to work together to light the subject properly. If you use a mirror and old AO Spencer focusing lamp with a diaphragm you can make any condenser work. But if you use the lighting built in the microscope you don't have enough adjustment to make every condenser work on ever microscope. The above and blow stage part don't need to be the same brand except phase rings must match DIC prisms must work together and any other thing that has parts on both sides of the subject generally need to match. Gordon |
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