| This TeleVue 1 micron digital indicator kit lets you index exact focus positions with an astonishing 1 micron (1/10,000”) accuracy for CCD photography. It can be used with virtually any recent TeleVue refractor having a 2” focuser with pre-drilled indicator mounting holes in top of its focuser body and drawtube. These include the TV-76, TV-85, NP-101, TV-102, and Renaissance 102.
The easily-installed digital indicator accurately reads out the focuser drawtube position on an illuminated display over a full 0.5” of focuser drawtube travel. It can also display the indicator readout on your computer by adding the optional 10’ TeleVue RS-232 cable #TVIKCAB and using the free TVFocus software available from TeleVue .
The main component of the kit is the battery-powered digital readout module. This has a compressing/expanding plunger that tells the readout module the focuser drawtube’s exact position. The readout module sits on a slide that is attached to the top of the focuser body using the supplied hardware. A plunger receptacle is attached to the top of the focuser drawtube. The scope is set at the approximate correct focus and the position of the readout module adjusted by moving the module slide until the tip of the spring-loaded plunger makes contact with the cone-shaped interior of the plunger receptacle. The spring-loading assures a firm and constant contact between the plunger tip and its receptacle. The readout module is zeroed out. Then, as you fine-tune the focuser position in and out over a +/- 0.25” range, the plunger follows the motion of the focuser and the focuser’s +/- distance from that zero position shows on the illuminated readout.
The mechanical positions of the readout module/plunger and plunger receptacle are saved after your first imaging session so that you can easily return to the same focuser positions during subsequent sessions. |
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