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Natural Science Forum / Physics / Optics / December 2007Wild M420
The recent postings on the Wild M5 caught my attention as I'm about to start trying to use the zoom optics module of a Wild M420. Could not afford a complete stereo stand ;>( But it will be used exclusively with a camera and monocular viewport, so not such a big deal. I was just wondering if any group member is familiar with this equipment. For starters, it would be nice to know if it an "infinity setup" out to the standard Wild binoc head or something else. I can view a very clear image with my eye at about 6-inches above the upper flange of the zoom module, with a working diatance of about 1- inch - as I recall. Any input will be very much appreciated!! Thanks and best wishes for the Holiday Season. -Keith. > The recent postings on the Wild M5 caught my attention as I'm about to > start trying to use the zoom optics module of a Wild M420. Could not [quoted text clipped - 16 lines] > > -Keith. Keith: There is nothing "standard" about an M420. If you do not already have it, go download the Leica brochure at: http://www.leica-microsystems.com/pdfs.nsf/(ALLIDs)/9B723B8DD03FE15AC1256A4D0044 75D3/$FILE/M1-421-0en.pdf You will see that it does not use a "standard" Wild binocular head for viewing. The optical path is pure vertical. Both eyes get to see the exact same (non-stereo) image for examination and framing. The aperture diaphragm is in the viewing head, so you need to consider how you are going to do something similar to control depth of field. The M420 was the second version of the Wild macroscope design. The first was the M400. The M400 was designed to use either a dedicated motor drive 35mm camera or a Polaroid setup, both with weird 50mm tubes inside a rectangular exterior rather than an ISO photo tube. It differed from the usual Wild stereomicroscope setup by having both the exposure sensor and the shutter built right into the module with the binocular eyepieces. There were 0.5X and 2.0X auxiliary lenses that could be added to change the magnification of the nominally 6.3 to 32 X 1:5 Makrozoom achromatic lens. The viewing head for an M400 can be updated at least two ways. McBain Instruments (the southern California regional Leica dealer) http://www.mcbaininstruments.com/ can put their version of an M420 ISO photo tube on it and take out the shutter. Or you can get a similar c-mount conversion kit from Lmscope: http://www.lmscope.com/produkt22/Wild_macroscope_C_mount_e.shtml The M420 went back to the usual Wild stereomicroscope setup of using a separate shutterpiece for exposure metering and framing. It used an ISO port for the camera. There were two zoom lenses sold for it. One was apparently the same achromat as the M400, the other was a new 1:6 Apozoom (Apochromat) using different auxiliary lenses (0.4X and 2.0X). Happy holidays! Graybald On Dec 22, 7:43 pm, r9...@yahoo.com wrote: > > The recent postings on the Wild M5 caught my attention as I'm about to > > start trying to use the zoom optics module of a Wild M420. Could not [quoted text clipped - 54 lines] > > Graybald Great post! Just a few points. The 400 series was designed for measuring things, primarily semi-conductor and metallurgical stuff. The real advantage is that it isn't a stereo so the measurement plane has fewer problems. If your interested take a look at the Nikon AZ100 (www.nikoninstruments.com/products.php?n=az100&p=Key_Features), its telecentric so it measures with even fewer problems. In the past not a lot of Wild 400 series were sold, they were expensive and only a few industries want them, but if you wanted one you had to have it. Times have changed, more people need to measure stuff so these instruments sell better. Thanks, Kevin Cunningham SMS Hello Graybald, Thank you very much for your informative post. >The optical path is pure vertical. Yes, this is exactly why I want to use the M420 module I have available - I don't know how I managed to include stereo in my post, probably because I'm usually trying to get images from a stereo stand! Of course, the superb M420 zoom is nice to have.... > ...aperture diaphragm is in the viewing head, so you need to consider how > you are going to do something similar to control depth of field. I'm OK with this as I have spare diaphragms that can be mounted in custom machined parts. However, the relay optics between the Makro zoom module and the camera may be more of a challenge? I may not have been explicit, but I do not have a viewing head. > an ISO photo tube. This is a simple tube without optics, but well specified diameter, etc - correct? -Keith > Hello Graybald, > [quoted text clipped - 23 lines] > > -Keith Keith: Happy holidays! It sounds like you understand depth of field control (aperture diaphragm). What you need to do now is to find the parfocal mounting point for your camera, relay lens, or imager. It will be a location where adjusting the zoom ring on the M420 lens does not require changing the distance to the subject to refocus. Maybe Leica headquarters or one of their dealers can tell you this. On my McBain converted M400 (with the zoom achromat) the top of the phototube is about 7-1/2 inches above the top face of the zoom objective lens. The Olympus photo eyepiece for my Diagnostic Instruments 35mm camera adapter is another 3/4 inch up from there. You did not say which zoom lens you have. I don't know if the location will be exactly the same for the achromat and the apochromat. What you want to do has been done before. Occasionally on eBay you will see a used Wild macrozoom (achromat) lens sold from New Mexico or California. Presumably they originally came from one of US national weapons labs (or maybe the semiconductor industry) and were built into custom imaging systems. Keep in mind that the M400 was introduced about thirty years ago, so the zoom achromat is not the most recent or very best current technology. My M400 system was rescued from the tool crib at Boeing Surplus in Kent, Washington. I cherish it because I know I never will find another similar scope for such a reasonable price. Macroscopes and stereomicroscopes are an excellent and versatile way to do photomacrography if you have the money and need to have a long working distance (4 inches) between the lens and the subject. There are other less versatile but cheaper set ups involving used macro lenses (or short focal length movie lenses, reverse mounted) and bellows on single lens reflex cameras. Nearly twenty years ago I was rummaging through some used 8mm and 16mm movie camera lenses at a camera show in the American Midwest. The seller told me he knew one of the insect photographers who wrote articles for Ranger Rick (a magazine for kids from the National Wildlife Federation). He said that guy used 13mm and 25mm focal length reverse mounted movie lenses glued on to plastic camera body caps. That is about $25 worth of used equipment rather than $2500 or $25,000. Graybald |
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