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| Beck microscope thing ? |
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| Pete W.:
Hi there, Rob, There are, I suppose, two main routes for buying microscopes these days. One is eBay and the other is through microscopy club/society sales. From your posts on Mad Modders, I guess you might not have the spare time to enter the microscopy club/society scene? I have bought most of our stuff through eBay. That includes four or five stereo scopes (but then my wife is also a microscopist and we gave one to one of my step-sons). Personally, I suffer from microscope/ebay addiction, it's a fairly common ailment but your existing addiction to CNC mills might keep you safe from it! :D You need to distinguish between stereo microscopes and binocular microscopes - they aren't the same thing. The stereo microscope is basically two distinct and separate microscopes mounted together at a slight angle. Each one has its own objective (but see below) and its own eyepiece. You can generally recognise them by the prism boxes (similar to binoculars - how confusing is that!?!). The prisms erect the image. The fact that each eye is seeing a different aspect of the object gives you the 3D or stereo effect. It IS a real effect, not an optical illusion. The binocular microscope, on the other hand, has only a single objective but the intermediate image from the objective is viewed via an optical splitter feeding two separate eyepieces. Each eye sees the same inverted image, there is no stereoscopic effect. Stereo microscopes usually have low magnification and generous working distance. Monocular and binocular microscopes can work up to a higher magnification at the expense of losing working distance. For example, the same Beck catalogue from which I quoted a few posts ago gives this for a 1/6" (4 mm) objective: Magnification x45, working distance 24 thou.! I don't think I'd want to be that close to a rotating workpiece unless the environment was very, very well controlled! :loco: Historically, microscope manufacturers specified the focal length of their objectives in fractions of an inch and/or mm because the tube length wasn't standardised. Eventually, a standard tube length was fairly universally adopted and, from then on, they could rate their objectives by magnifying power. Regarding stereo microscopes - the really modern whizzy hi-tech (and hence expensive) models can have zoom and some have their two optical paths looking through a common (but low-mag) objective. Most models have a focussing mount and some sort of stage for the object being viewed but there are models configured for 'long-arm' mounting without a stage. I've been looking for a photo but, so far, the only pix I've found are other peoples, not in the public domain. You could try a Google. Microscopy enthusiasts, like Radio Amateurs ('hams') seem to expect to buy cheap and sell dear, I personally don't do well in the market place. In fact, some eBay sellers, to quote a friend of mine, 'need to take a reality pill'! What I did was to browse eBay and bid what I thought an instrument was worth to me; if I was outbid, my money was still in the bank. There IS a learning curve to climb but I guess that also applies to CNC mills! I hope this helps, Best regards, Pete W. |
| Pete W.:
Hi there, again, Rob, Have a look here: http://www.history-of-the-microscope.org/types-of-microscope-stereo-microscope-binocular-microscope.php Best regards, Pete W. |
| Rob.Wilson:
Hi Pete Thank you for post , allot of info :bow: :bow: , and can tell you sure have a thing for microscopes :med: :lol: :lol: :lol: :lol: my addiction to machines is coming to an end ,,,,i am dooooomed ,,,,,,,running out of room :Doh: Wonder how much a copy of Hooke's Micrographia would go for . So what sort of things do you look at through your microscopes ? can you take photographs of what you see ? Thanks Rob |
| Pete W.:
--- Quote from: RobWilson on November 07, 2012, 04:57:12 PM ---Hi Pete Thank you for post , allot of info :bow: :bow: , and can tell you sure have a thing for microscopes :med: :lol: :lol: :lol: :lol: my addiction to machines is coming to an end ,,,,i am dooooomed ,,,,,,,running out of room :Doh: Wonder how much a copy of Hooke's Micrographia would go for . So what sort of things do you look at through your microscopes ? can you take photographs of what you see ? Thanks Rob --- End quote --- Hi there, Rob, First of all about Hooke's Micrographia. Antiquarian books are a financial black hole that, so far, I've managed to avoid! Despite that, over the years I have built up a reasonable library of books on microscopy. Hooke's illustrations are amazing, considering that they were all drawn by hand. On the subject of Hooke, someone I regard as a 'microscopy cyber-mentor' has recently been experimenting with a replica of Hooke's microscope, including illumination by oil lamp (not quite historically accurate because whale oil isn't in ready supply nowadays! :D ) Some of his photos, very impressive, are in the photos section of the Yahoo microscopy group. What do we look at? Well, most of the observation in our family is currently done by my wife. When we took up microscopy, we decided that we didn't want to kill and cut up stuff. Her interest is in pond life and that mostly survives her observations and gets back into the pond. At the moment, my microscopy time seems to be taken up with 'make do and mend'. A couple of years ago I bought a Leitz microscope with built-in illumination from an eBay seller in the USA; of course, it was wired for 115 volts so we used it with an autotransformer. More recently, an orphan base for the same model wired for 240 volts turned up so I bought it and did a base transplant. Another Leitz microscope I bought arrived in pieces - the helical pinion that operated one axis of the mechanical stage was bent over at a crazy angle and several of the screws that held the linear ball-race guides on the stage had sheared-off. I assume that it had been accidentally knocked off the laboratory bench! Spares for that model are only available at professional prices and there was no way I could manufacture a new pinion with its all-in-one shaft. However, you never know what's going to turn up and an identical pinion (but with a shorter shaft) turned up on eBay from a seller in Canada. I successfully lengthened the spindle, replaced the sheared screws and the missing 2 mm balls and, voila, a usable microscope. :ddb: A lot of microscopes in amateur use have fairly unusual tungsten filament bulbs. These are expensive even if replacement bulbs are available and this situation looks likely to get worse with the EU policy to outlaw tungsten filaments. There's a lot of interest in converting to white LED illumination and I have some ideas on that subject that I hope to put into practice soon. We suffer from a problem in our household that any horizontal surface soon gets covered with 'stuff'! :bang: It's particularly so in the workshop and trying to deal with that and fight-back some bench space isn't allowing much time for microscopy just now. When I do get back to it, my particular interest is in sand. We live on the East Hampshire greensand - the thing about that is that it's never green, usually silver or a 'dirty yeller colour'! I'm told it does look green if you see it in large lumps, say, in a cottage wall. (Once it weathers down to powdered sand the glauconite that gives it the green colour gets washed away.) I got into the habit of picking up samples of sand while I was walking the dog on various local tracts of heathland, I used to describe myself as a 'rabbit-hole geologist! Then I enlisted various globe-trotting friends and acquaintances to bring me back samples from their travels. The collection currently includes samples from as far afield as Sydney Harbour, Baja California, Saudi Arabia and various places in Africa. To examine those properly requires that I do some renovation to a petrological microscope, another item on the to-do list. I think that I did get a bad name with the local Utility Companies - as soon as they dug a deep enough hole in the ground to mend a cable or install a pipe, I'd turn up with a couple of 35 mm film canisters (just the right size) and try to scrounge a sample! You ask about photos: we do have an eyepiece USB camera but the laptop computer dedicated to that has just died! It doesn't 'do' many megapixels but the optics of microscopy mean that we don't need lots of megapixels for the stuff we look at. Maybe I'd get more microscopy done and more results in the workshop if I didn't spend so much time in front of this computer looking at forums and bulletin boards!! :bang: so I'd better sign off now. Best regards, Pete W. |
| DMIOM:
--- Quote from: RobWilson on November 07, 2012, 04:57:12 PM ---...... my addiction to machines is coming to an end ,,,,i am dooooomed ,,,,,,,running out of room ............. --- End quote --- Rob, I can't attempt a "Mr Creosote" impression but do you think you might find room for an itsy-bitsy teeny-weeny surface grinder? Dave :headbang: |
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