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Natural Science Forum / Physics / Optics / October 2007What is a metallurgical objective?
Yes, I know, it's for metallurgy! But how do the optical properties of these objectives differ from normal brightfield ones? How might they be expected to perform for biological applications, for example? On Oct 21, 11:31 am, UKOncol...@aol.com wrote: > Yes, I know, it's for metallurgy! But how do the optical properties of > these objectives differ from normal brightfield ones? How might they > be expected to perform for biological applications, for example? Metallurgical objectives are meant to be used with reflected light and without a cover slip (or cover glass). The optical tube length is longer (typically 170mm or even 210 mm) versus 160mm in order to allow room for the vertical illuminator. Therefore they would be expected to deliver lower performance than biological objectives. Pittsburgh Pete DISCLAIMER We do not believe what we write, and neither should you. Information furnished to you is for topical (external) use only. This information may not be worth any more than either a groundhog turd, or what you paid for it (nothing). The author may not even have been either sane or sober when he wrote it down. Do not worry, be happy. On Oct 21, 1:31 pm, UKOncol...@aol.com wrote: > Yes, I know, it's for metallurgy! But how do the optical properties of > these objectives differ from normal brightfield ones? How might they > be expected to perform for biological applications, for example? Pete's right, mostly the difference is that met objectives don't use cover glasses. However no one uses tube length any more. Now every thing is infinity corrected. Another big difference is now all met microscopes have standardized magnifications at 5, 10, 20, 50 and 100 times. The quick answer is usually met objectives won't work for biologically prepared specimens. Thanks, Kevin Cunningham SMS > The quick answer is usually met objectives won't work for biologically > prepared specimens. Well, they work, and you might not notice that you're not getting top quality, but a conventional objective that works better is less expensive. On 21 Oct, 18:31, UKOncol...@aol.com wrote: > Yes, I know, it's for metallurgy! But how do the optical properties of > these objectives differ from normal brightfield ones? How might they > be expected to perform for biological applications, for example? Assuming epi-objectives are "metallurgical objectives", I find the darkfield ones work well in some niche applications. I got nice closeups of stomata by stacking shots in HeliconFocus. Brightfield doesn't work too well visually - far too much glare - but you can get reasonable results photographically with heavy processing. All of this on fresh leaves or wood etc - no coverslip... > On 21 Oct, 18:31, UKOncol...@aol.com wrote: > I got nice > closeups of stomata by stacking shots in HeliconFocus. when i try to assemble the images with helicon the single frames are dislocated, so the final image presents borders of the images below can i know the reason of it? > > On 21 Oct, 18:31, UKOncol...@aol.com wrote: > > I got nice [quoted text clipped - 4 lines] > > can i know the reason of it? Couple of possibilities... 1. You are not using enough images and your individual focus planes are too far apart. Take more pictures more closely spaced (in z), that definitely solves the "stairstep edges" problem - which is most likely what you're seeing... 2. In the options, ensure the ability to shift the image left and right during alignment is enabled. However, I always turn off the option to allow rotation for alignment as that sometimes does the wrong thing and leaves edge artefacts Hope that helps... >> > On 21 Oct, 18:31, UKOncol...@aol.com wrote: >> > I got nice [quoted text clipped - 18 lines] > > Hope that helps... yes , that helped : ) |
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