Andrew,
I thought this up years ago and I haven't seen it published or used elsewhere. I'm basically lazy and will always try and find the easiest method as long as it works. This method is not useful for flats but is meant for more strongly curved lenses and mirrors. lenses especially have stronger curves and the masking tape method is totally useless in many cases.
The channels in pitch allow the pitch to flow as it conforms to the curve and the size of the squares is a function of both the pitch hardness and thickness. If your pitch acts too hard (no flow) then you must either add more channels or pour it thicker, still better is to just remake it adding a little solvent to make it softer. On the other hand if the pitch is too soft it will flow too fast and you should pour it thinner to compensate. I think the thinnest possible pitch will give you the best sphere as long as it still flows. I think what you are refering to is that primary ripple is related to the spacing of the channels. I make my channels by eye and they are never the same width and more importantly keep the channel width small to prevent this.
I polish with cerium oxide and finish with Opaline. I got tired of turning everthing including myself red and Opaline actually does better job and doesn't scratch.
I'd never make an F/4 Newt., too much coma, too hard on eyepieces more difficult to figure.
"Any tips for slower f ratios besides a tester?", you mean testing tips? For the first time mirror maker I recommend the conjugate null.
Ed Jones
I thought this up years ago and I haven't seen it published or used elsewhere. I'm basically lazy and will always try and find the easiest method as long as it works. This method is not useful for flats but is meant for more strongly curved lenses and mirrors. lenses especially have stronger curves and the masking tape method is totally useless in many cases.
The channels in pitch allow the pitch to flow as it conforms to the curve and the size of the squares is a function of both the pitch hardness and thickness. If your pitch acts too hard (no flow) then you must either add more channels or pour it thicker, still better is to just remake it adding a little solvent to make it softer. On the other hand if the pitch is too soft it will flow too fast and you should pour it thinner to compensate. I think the thinnest possible pitch will give you the best sphere as long as it still flows. I think what you are refering to is that primary ripple is related to the spacing of the channels. I make my channels by eye and they are never the same width and more importantly keep the channel width small to prevent this.
I polish with cerium oxide and finish with Opaline. I got tired of turning everthing including myself red and Opaline actually does better job and doesn't scratch.
I'd never make an F/4 Newt., too much coma, too hard on eyepieces more difficult to figure.
"Any tips for slower f ratios besides a tester?", you mean testing tips? For the first time mirror maker I recommend the conjugate null.
Ed Jones
