Home made Focal Reducer ?

[ultramol]

I saw a video on you tube of an australian guy making a focal reducer with a lens out of an old pair of binoculars. Is it this simple or is there a snag to this ?

[michael.h.f.wilkinson]

Any (achromatic or apochromatic) lens placed fairly close to the image plane can be used for flattening. By close I mean a lot closer than its focal length. Getting the distance right, and avoiding introduction of aberration such as spherical aberration is of course an issue. A home-made one may also have issues with collimation.

[ultramol]

Thought it was to good to be true.....

[Herra Kuulapaa]

Sometimes people make refractors themselves, but usually not for imaging purposes. It think same goes for the reducers as well..