[PRejto (Peter)]

Sorry, a very basic question. Generally speaking what does a flattener/reducer do to the focus point with respect to prime focus? Does the flattener move the focus in or out from the prime focus location, and (if possible to answer generally) how much in or out.

Specifically I'm asking about my TEC140 and a Borg reducer/flattener part 7870 .7X. It's a new product and I'm trying to figure out if it might work. I've been in contact with Hutech but the answer I'm getting is not very clear. With all the tubes and adapters in place I would need to move the focuser 18 mm out (from fully wound in) to reach the same position as prime focus. So, If focus is more than 18 mm inside prime focus this won't work, but if outside prime focus then it ought to be ok. I realize nobody has this product so I'm only looking for a ballpark sort of figure based on others experience.

Thanks!
Peter