I meant that if you are going to flock your tube in essence you are trying to improve the contrast of the image produced by the scope.
Off axis light (ambient light) is one of the worst enemies of contrast and we are trying to reduce this. So:
- We flock the tube with an extreme flat black material to reduce any reflections to the minimum possible so and off axis light that enters the front of the tube is not bounced off the side of the tube to the mirror.
- We baffle behind the mirror so light cannot sneak in around the mirror edges and start bouncing around but it still has to allow for air flow. This light we can eliminate so its best to do it, especially if we are in light polluted areas.
- We "extend" the OTA 1.5x the mirror diameter in front of the focuser. By extending the tube we stop off axis light from directly entering the focuser and reducing contrast. If you get light in there it bounces around in your eyepiece and you end up with a really washed out image. Why 1.5x the mirror diameter? Its generally accepted that this length will stop the problem, any less could allow some ambient light into the focuser. But more is not necessarially better as it adds weight to the front end of the scope and can get into the light path and reduce the light gathering capabilities of your scope.
Does all that waffle answer your question?
Cheers