I'm trying to modify a De Oude Delft 50mm/.75 to be actually usable so there's that I guess. No pics because the actual lens comes in tomorrow and all I have right now are a bunch of spare elements, diagrams by hand that are messy, some equations, a few tests on a free raytracer, and of course, a few bookmarks to buy overpriced single glass achromatic concave coated-glass elements online (between 30-90 dollars each for the elements I think I'll need if I can't find a better solution)
pic related is the lens diagram for the de oude delft. Yes, the distance from the back element to the focal plane is really that small. Otherwise I would have no need to take it apart and buy new elements / reuse old elements from other lenses. The filter thread is 77mm
>>3254502Cute letters and all, but more importantly, what will be the opening size, what's the size of the box, what's the f stop, and with all of that do you have an image circle that'll cover a satisfyingly large amount of the paper? Also is the hole just gonna be in the box? If it is then make sure it's a clean hole otherwise you'll get foggy and possibly reddish pictures (if using color photographic paper) from diffraction. At 8x10 I'd imagine you start getting nasty refraction above f/256. Also keep in mind that the f/number is going to give a different depth of field on 8x10 than on full frame equivalent. For example f/64 with 8x10 is equivalent to about f/5 at 35mm (quick calculation shows that 35mm crop factor from 8x10 is 12.7x) so plan according with your subject if it's not at/close to infinity.
I've never done a pinhole box but I modified a lens once to have an internal diaphragm pinhole. It was my first lens modification and looked like garbage, don't even know what the aperture ratio was kek. I'd image f/64ish since I made a nasty ass hole bigger than I wanted.