iPad to Telescope Bracket for Generating Flats

thingiverse

This device is used to hold an iPad firmly against the lens of a 4 inch refractor telescope in order to create a flat field image for astrophotography. Astrophotographers typically combine three types of pictures in order to create the beautiful astro photos we see published today. These pictures are labeled Lights (the actual picture of the night sky taken through the telescope), Darks (the noise created by long exposures with a lens cap installed) and Flats (a picture through the telescope of a uniformly lit source used to remove lens vignetting and dust moats). Multiple pictures of each type are taken with the darks and flats subtracted from the lights in order to create the final image. This Thing is a device to aid in creating Flat pictures using an iPad as the light source. There are many ways to create a uniformly lit flat field used to create Flats. Some people use a t-shirt wrapped over the end of the telescope while pointing it at a light source. A more elegant way to do this is to use an iPad with a gray or white image on the screen. Some people balance the iPad on the telescope end while the telescope points upward. This is very risky however since the expensive iPad can be knocked off and destroyed. This bracket prevents this by gripping the telescope lens and it also grips the sides of the iPad making for a more secure connection. This Thing is used to hold an iPad against the Explore Scientific 102mm (4 inch) telescope. A uniform gray image can be displayed on the iPad in order to create a flat field image for the telescope. A sheet of paper on the iPad helps to diffuse the light even more. Four identical sliding brackets help to grip the iPad to the fixture. Rubber bands are used to bias the grippers. 3mm diameter by 6 to 10mm long metric screws are used to hold the grippers. #4 machine screws by 3/8" length could alternatively be used. Note that the screws must not extend beyond the platform surface as this might harm the iPad screen. Please check this before installing the bracket onto the iPad. Also note that this bracket will hold the iPad onto the telescope but it is not a rigid connection. The iPad can still fall off if the telescope is pointed sideways or downward. Only use this when the telescope is pointed vertically upward. Please use caution. This bracket was designed specifically for the Explore Scientific 102mm refractor. Other sizes may be made in the future as time permits. The actual outside diameter of the lens this bracket is designed for is 120mm. The actual width of the iPad it is designed for is 175mm.