Quote:
Originally Posted by anj026
Mark if you ever offer an 8" f12 coated achromat lens in cell I would be interested. D&G offer them for the price of $2395 USD plus $275 USD for simple coatings on all four surfaces. That would be over $4000 AUD and who knows how long you would have to wait for it, maybe years.
I don't know if it would be commercially viable for you to make a run of them in Australia. What do you think?  |
Andy : Probably wouldn't be viable - I would expect a hefty expense on the AR coatings , USA sourced glass and adjustable mirror cells. Probably a fast track to working for $10 an hour committing to a production run on something like that !.
I suspect what D nd G would be batch polish production runs of elements getting radii of surfaces more or less right but not worrying to do much surface figuring . They would then mix and match lenses to find pairs producing the best wavefront , then do some quick localised polishing on the rear element surface to achieve an optical null and decent star test . Just my guess for that price , but I may be wrong .
As I said I am interested in making a large achromat for fun at some stage with a view to making a large oiled triplet down the track . Oiled triplets have always appealed to me as the two oil mated surfaces have next to no surface quality tolerance and don't have to have AR coatings. So after mating there are no more complications beyond that of mounting and aligning a doublet. I have no idea why they aren't more common, but it is probably to do with less design freedom in that the mated curves of the oiled elements have to be more or less matched in radii.