Description of Alstar Astrophotography Mirror Eyepiece Adapter
An object that is accurately centred in the eyepiece will be simultaneously centred in the camera's field of view. You no longer have to worry about whether the object is correctly positioned on the chip - you know it will be. For precise focusing: In astrophotography, if you want to take successful astronomy photographs, accurate focusing is only one half of the story. The Alstar flip mirror makes it very simple to find both the exact focus point and also the correct positioning for your astronomy photographs. This small black box has a moveable flip mirror which shunts the light path 90°upwards or, alternatively, lets it pass through unhindered. Always sharp: If you tilt the mirror to the 45° position, the object will then appear in the eyepiece and you will be able to precisely focus it as usual. The helical focuser on the flip mirror lets you make the eyepiece and camera exactly parfocal with each other. This means that both elements will be in focus at the same time. Connectability: The Alstar flip mirror has a 1.25" connector which will fit onto any standard telescope. The helical focuser will accept any standard 1.25" eyepiece. There is a T-2 thread provided on the camera side - the standard fitting for all cameras. An advantage with all cameras: No finder is provided with popular webcams or astronomical CCD cameras for helping position the object on the chip. Only by taking test exposures is it possible to achieve both sharp focus and the correct object position. The flip mirror is a big help here as the object has already been centred and focused 'remotely' on the chip via the eyepiece.