Conventional focal reducers rarely work with Newtonians because they lack sufficient in-focus. Still, I'd like to increase the field of view of my CCD, which is about 10mm corner-to-corner. Three-fold would be nice.
So, I propose putting two eyepieces front-to-front, with their eye lenses separated to make their exit pupils coincide. One, say a 35 mm would be in the normal position in the telescope, converting the real image formed by the primary into a virtual image at infinity. The second, say 12 mm, would focus the image at infinity down to a new, real image of 12/35 the size of the original, focused on the CCD which would be placed at the position of the 2nd eyepiece's field stop, which must be accessible.
With a 10mm final field diagonal, the eyepieces would need a good 45-degree field of view.
I hope that using both eyepieces at their infinity focus will minimize image defects.
Can anyone suggest the (probably obvious) defects in this idea? Will there likely be problems with vignetting or field flatness?
If this is a good idea, does anyone make and sell them?
So, I propose putting two eyepieces front-to-front, with their eye lenses separated to make their exit pupils coincide. One, say a 35 mm would be in the normal position in the telescope, converting the real image formed by the primary into a virtual image at infinity. The second, say 12 mm, would focus the image at infinity down to a new, real image of 12/35 the size of the original, focused on the CCD which would be placed at the position of the 2nd eyepiece's field stop, which must be accessible.
With a 10mm final field diagonal, the eyepieces would need a good 45-degree field of view.
I hope that using both eyepieces at their infinity focus will minimize image defects.
Can anyone suggest the (probably obvious) defects in this idea? Will there likely be problems with vignetting or field flatness?
If this is a good idea, does anyone make and sell them?