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#31
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Newbie question about macro with DSLR
tony cooper wrote:
Microscopes can be very expensive, but it is unlikely that you need a fancy one. It should be fairly easy to find an older used model that will do fine. They often are available on eBay at reasonable prices, as are the parts and pieces such as objectives and "relay lenses" for photography. Keep in mind that objective lenses are matched to the eye pieces (and to the relay lenses used for projecting into a camera), and hence should not necessarily be mixed and matched between manufacturers. I can't figure out what you're saying here, and I'm pretty familiar with microscopes. I have no idea what "relay lenses" are. They are what the words say. I own a late 1990's inverted Zeiss Axiovert microscope, a top of the line gizmo. The objective sends the light, COLLIMATED, through an optional beamsplitter used for epi-fluorescence. This beamsplitter lets the fluorescence through, and reflects the light that comes IN to excite the fluorescence. It also contains transmission filters for the incoming and outgoing light. It is optional, and is not used for brightfield illumination. This is not a metallographic microscope and does not have darkfield. The light then continues downward through a "tube lens". This is a lens of 163 mm focal length that focus the collimated light. The light then goes out the bottom of the scope onto a TV camera. There is a mirror that slides into this path and reflects the light up toward the eyepiece. But it focuses too soon, so there is a field lens near the focus, and, farther on, a set of relay lenses that image the first virtual image, at the field lens, up into the eyepiece assembly. That's what a relay lens is used for. Because Zeiss now uses "tube lenses", an objective from my scope would not, by itself, work properly as a camera lens. You would need the specific Zeiss "tube lens". Different companies (i.e. at least the big three, Nikon, Zeiss, and Olympus) make different tube lenses. They are part of the aberration correction system and using the wrong one will result in lateral chromatic aberration. Olympus used to sell ... maybe still does, and you certainly can get used, objectives that do NOT need a tube lens, instead doing all the focusing themselves. Some of these, unfortunately, don't correct the later chromatic, instead leaving that to the eyepiece. However, many of them (or rather did). Any one that was intended for photography without a tube lens did. Doug McDonald |
#32
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Newbie question about macro with DSLR
I wrote:
I've looked at the Olympus site, and am somewhat lost. If it's not too much trouble, can you give me any more specific idea as to what I'm looking for? Floyd L. Davidson wrote: [lots of good advice and references, including...] The Olympus webpage has much good info, and these are a couple to start with: http://www.olympusmicro.com/primer/faq.html This one is long with lots of general information: http://www.olympusmicro.com/primer/microscopy.pdf [etc.] Thanks! That was exactly the sort of information I needed! Eric |
#33
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Newbie question about macro with DSLR
Doug McDonald wrote:
What are you going to photograph? PMOS integrated circuits fabricated between 1975 and 1978. Minimum feature size (as drawn) is at least 3 microns. Remember that lenses are available at 20x magnification that will resolve .5 micron ... that is, 1000 line pairs per mm. Really? Can you point me to any specific models? Thanks! Eric |
#34
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Newbie question about macro with DSLR
Archibald wrote:
You should also be able to achieve this by reversing an ordinary Canon lens. [followed by a detailed explanation] Thanks for writing that up! Eric |
#35
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Newbie question about macro with DSLR
Floyd L. Davidson wrote:
You need a microscope. I suppose you're probably right. I was hoping some other, less expensive possibilities, like a Raynox MSN-505 or CM-3500 conversion lens used with a telephoto lens might do the trick. I can probably find other uses for the conversion lenses anyhow, so I don't mind buying them even if they don't work out for my current project. Do you want _each_ image to be even higher magnification than stated above, and for the resulting final product to be as described above???? Or do you mean each exposure will capture 0.5 to 1.0 mm of a larger object? The overall size of the subject is under 10mm on a side. I wanted to get shots of 0.5 to 1.0 mm square portions of that, then stitch them together. If you mean that each exposure will capture 1mm of an object, then a typical dissecting microscope would be appropriate (and would be very convenient to mate with your X-Y state). Another possibility is a toolmakers metallurgical microscope. OK, I'll look into those. The feature you'll want to look for is the ability to mount it in a way that you can use your X-Y stage (which is not true of all metallurgical scopes). Some of the relatively inexpensive microscopes I've looked at have a single-boom or double-boom mount that should do that. I'm not sure which would be better for stability (vibration). Another feature, which is almost universal though there is a chance you don't need it, is episcopic (or "epi" for short) illumination. That uses a beam splitter to illuminate the object through the same optical path that you view it. (That is probably _very_ useful to you.) Definitely. I hadn't even heard of it. The microscopes I've looked at have ring illuminators, which obviously wouldn't be useful if the objective has to be very close to the subject. Thanks for all the advice! Eric |
#36
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Newbie question about macro with DSLR
Eric Smith wrote:
Doug McDonald wrote: What are you going to photograph? PMOS integrated circuits fabricated between 1975 and 1978. Minimum feature size (as drawn) is at least 3 microns. Remember that lenses are available at 20x magnification that will resolve .5 micron ... that is, 1000 line pairs per mm. Really? Can you point me to any specific models? Thanks! Eric Unfortunately, not usefully. I can point to plenty of ones that need a tube lens, but not ones that don't. They do exist. Remember this: resolving power is determined by "numerical aperture", N. A. f/number = 1 / (2 * N. A.) (for lenses working in air) In other words an N. A. 1.0 lens is f/0.5 0.5 lens is f/1.0 0.3 lens is f/1.6 etc. resolving power, defined as the half-width of the blur function at the subject, is roughly f/number, in microns. In other words, the blur of an N. A. 0.5 objective is about 1 micron. This is fairly rough, formally it is actually 0.83 microns. You don't need a big-name objective to get the job done. Google on "microscope objectives". You need a "plan" one (i.e. flat field) for "no tube lens" or NOT "infinite focus" and also if it matters for that objective, NO COVER GLASS. Also, you need to worry about working distance if you intend to send light in from the side. I found many objectives that will work under $150 ... but I didn't check to see if they will work well with no cover glass. Doug McDonald |
#38
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Newbie question about macro with DSLR
Joseph Meehan wrote:
"Jürgen Exner" wrote in message ... ... Yeah, for whatever reason Nikon calls "Micro" what everyone else calls "Macro". Yea. Frankly everyone else is wrong, :-0 Well Nikon is wrong in their use from time to time as well. I don't think it is going to get straightened out, but it is good to keep in mind that there are two terms and that we should all expect them to be used properly and improperly so we don't assume that they will be used in the manner we expect. Nikon calls them micro because they already used macro for an obscure old line of extreme closeup lenses: http://www.naturfotograf.com/lens_spec.html |
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