Optosigma stage with micrometer
This kind of device is essential for fine focusing and taking picture with microscope objective mounted on macro bellow. The device have to be placed between a stand (example an old enlarger) and the macro bellow.
The best device for this purpose is probably a Velmex Unislide with a long and precise (depending on the model) X axis translation travel but they weren’t appearing on ebay while I was looking for them (I think I need a 40 turn per inch). So I first purchased a Del-Tron micrometer slide for which I wasn’t able to find the right screw (1/16 in imperial measure) to adapt a Manfrotto quick release. I finally (I hope) bought this OptoSigma precision slide with micrometer.
Description
This OptoSigma is a very fine piece of precision engineering.
- The upper stage is drilled in the centre with a 6mm threaded hole and 8 smaller holes in the corner and in the middle of each side.
- The lower stage is drilled with 4 holes in each corner (the screw are provided on my copy) and with 4 other holes along the axis.
- The micrometer is located on the side of the device. The barrel bear 13 marks (every millimetre) and the knob bear 50 graduations. Each turn of the knob give a movement of 1 mm. Each graduation on the knob correspond to 20µm.
- On the opposite side of the micrometer is located a knob to hold the 2 stages in place if desired.
- There is no dovetail but rails and nylon (?) bearing along the path. The return of the stage is allowed by 2 springs visible at the maximum extension of the device.
- A lot of head screw are visible on the sides of the device. I think they are holding some internal parts and are not supposed to be used for settings.
Specifications.
- Dimension : 40mm x 40mm
- Travel : ± 6.5 mm
- Load capacity : 9 kg
- Minimum increment : 3µm
- Material : steel
Concern :
- The travel is very short on the device. Something else is needed to run a first rough focusing.
- Maybe too much turn between 2 shots with a 4x objective.
- Strong enough to hold vertically a Ihagee macro Bellow and a Panasonic GH1 ?
- As the back movement is spring loaded, it may be better but less handy to have the micrometer knob downward.
- The position of the micrometer (on the side) may be less handy than a micrometer at the rear of the stage. BTW, the best seems to be the Velmex Unislide on this point.
Adapting the Manfrotto quick release on the slide.
- For the socket part of the quick release it’s rather easy as there is a 6mm threaded hole on the upper stage. We only had to dig a space in the Manfrotto plate for the screw head to allow the insert of the quick plate of the bellow.
- To hook the lower stage to the quick plate it’s a little bit more tricky as we had to drill threaded holes in the plate and as the plate is as large as the slide, we were unfortunately able to fix it with only 2 screw. As the coupling is only made on one side of the device, there is some backlash in the setting and I will have to have the coupling screw in the upper side of the macro bench to minimize this backlash.
Links.
- Page on the device on the OptoSigma website.
