Focusing a Schneider 35mm/5.6 with center filter in weak indoor light on the ground glass can be rather challenging.
The trick I'm using today is to focus before framing: aim the camera/lens directly towards the object I want to focus at so I get to focus in the direct center of the lens => no tilting of the loupe required and there's no sideways movement from the focus breathing so it becomes considerably easier. If there's only low contrast objects where I want to focus I can put some high contrast object there as focusing target, like a small bright LED clock (bright light and sharp shapes). With this method you cannot fail even in these poor conditions
.
However, it would be cool if one could instead of that LED clock as focus target use a laser pointer (so you don't need to walk into the scene), which I could mount in an arm in the cold shoe on the camera and aim at the place I want to focus at. For this to work the laser must be bright enough, and I think it should have some shape, such as a crosshair, as a point is more difficult to focus-peak than a shape. I've tried to focus on the laser point from a Leica Disto D5, and it sort of works, but the point is not too easy to peak at, a well-defined sharp shape would be better.
Has anyone tried this method and have a recommendation for laser pointer product?