Thingiverse
Mantis Stereo Microscope Long Working Distance (SLWD) objective lens adapter by DogP
by Thingiverse
Last crawled date: 4 years, 1 month ago
I use my Mantis stereo microscope to do a lot of soldering, and one of the difficulties when working on high density boards (BGAs, tightly packed 0201s, etc.) is that it's hard to get the soldering iron(s) and/or hot air tool at the necessary angles because the microscope head is too close and gets in the way.
There is an official long working distance 6x SLWD objective from Vision Engineering meant for rework, but it's very expensive, so I decided to try making one myself with various optics I had laying around. Previously, I created a set of objectives based on jeweler's loupes ( http://www.thingiverse.com/thing:222849 ), and this is an extension of that work.
In order to increase the working distance, it uses a concave lens before the standard magnifying convex lens. I pulled the concave lens from a cheap 37mm 2x telephoto lens (Zeikos ZE-2X37B, ~$5 on ebay), and the convex lens from the jeweler's loupe set again.
The design in this thing gives approximately 5x magnification when using the Zeikos convex lens and the "10x" loupe lens. The approximate specs are: field of view=24mm depth of field=8mm, working distance=145mm. You can adjust the parameters by using different lenses and/or extending/shortening the length of the tube.
Like my other design, it also allows you to "stack" a lens if you need more magnification by twisting on "loupe_lens_adapter_twist" from thing 222849. By stacking the "2.5x" lens, it increases the magnification to approximately 9x, but reduces the working distance to about 75mm, and stacking the "5x" lens takes it up to around 12x w/ a working distance of about 55mm.
The image quality of this objective is good, though obviously won't be as good as an actual Vision Engineering objective... but the total cost is around $10, compared to $500 or so (used). The viewing "sweet spot" on this long working distance is smaller than that of my regular lens adapter (i.e. it blurs when you move your head off center), so I typically use the regular lens unless I need the extra working distance. You may be able to improve that by using a less concave lens (which would decrease the working distance), using a shorter tube with a higher magnification convex lens, and/or using a larger diameter convex lens (just some ideas... I didn't try them).
There is an official long working distance 6x SLWD objective from Vision Engineering meant for rework, but it's very expensive, so I decided to try making one myself with various optics I had laying around. Previously, I created a set of objectives based on jeweler's loupes ( http://www.thingiverse.com/thing:222849 ), and this is an extension of that work.
In order to increase the working distance, it uses a concave lens before the standard magnifying convex lens. I pulled the concave lens from a cheap 37mm 2x telephoto lens (Zeikos ZE-2X37B, ~$5 on ebay), and the convex lens from the jeweler's loupe set again.
The design in this thing gives approximately 5x magnification when using the Zeikos convex lens and the "10x" loupe lens. The approximate specs are: field of view=24mm depth of field=8mm, working distance=145mm. You can adjust the parameters by using different lenses and/or extending/shortening the length of the tube.
Like my other design, it also allows you to "stack" a lens if you need more magnification by twisting on "loupe_lens_adapter_twist" from thing 222849. By stacking the "2.5x" lens, it increases the magnification to approximately 9x, but reduces the working distance to about 75mm, and stacking the "5x" lens takes it up to around 12x w/ a working distance of about 55mm.
The image quality of this objective is good, though obviously won't be as good as an actual Vision Engineering objective... but the total cost is around $10, compared to $500 or so (used). The viewing "sweet spot" on this long working distance is smaller than that of my regular lens adapter (i.e. it blurs when you move your head off center), so I typically use the regular lens unless I need the extra working distance. You may be able to improve that by using a less concave lens (which would decrease the working distance), using a shorter tube with a higher magnification convex lens, and/or using a larger diameter convex lens (just some ideas... I didn't try them).