-DannyMy warehouseMy Channel
Ed Jones ........... The best data is an interferogram, the best analysis is from an honest optician.
Homemade 'scopes 8"f/7,6" f/5", 6"f/4, 4.25" Schiefspiegler,60mm Coronagraph,60mm H-alpha system, 4.25" White-light Solar Newtonian,solar spectroscope, 4" f/12, 4.5" f/16 & 6" f/12 Schupmann Medial refractors, 4" Celestar, 19 Stellafane awards 9 in optics Engineering = Taking what you have and making what you need.
7x50 tasco binoculars, 60 mm tasco refractor, 10" f/6 dob, (4" f/14 newtonian)
Quote:I recommend using a round blank then cutting it elliptical if needed. I'm starting to hate working with (Newtonian)ellipses. The sides aren't even vertical. How much is gained using an ellipse than a round one? 3% light loss and contrast?
Quote:Mladen, Unfortunately you are correct only for contact testing of flats. Not using a collimator for the water test would result in a non-flat optic unless you do fringe analysis.
Quote:a 6.5" x1" thk flat for $89you can test and return it in 14days if its not flat...it could always be a good pressing flat.
Living at a dark site, I make scope when I have the inclination. I also do woodworking, cycling and other outdoor activities
Quote:The fringes do wiggle around but it's not a big deal. Take a look at this video of a 4 1/4 diagonal tested on the water test. It doesn't detract from the usefulness of the test.
Quote:So is that flat convex?
Quote: Dick Parker who uses the water test on regular bases discover that if he used a clay pot to hold the water, that the wicking action of the clay slowly changed the level of water and he could observe the fringes moving. If they moved inward the surface was concave and if outward convex. - Dave
Quote:Dave,do you use gugolz 73 for flats also?