Re: New 75mm Hypergon Lens
How about a circular race ball bearing mechanism surrounding the lens? The "fan" itself (laser cut from thin aluminum and black anodized) would consist of two or three blades...wider in the middle and tapering to very thin where they intersect the edge of the race at three points. The blades would obviously need to be curved downwards towards the edges as the race itself would need to be quite low-profile, so as not to interfere with the image field.
The outside of the race could be cut with gear teeth (or a ring gear attached to the outer circumference)...which are driven by a spring wound mechanism which would be cocked and fired like a shutter. Could utilize something like a slow speed mechanism (could use an existing one?) to keep the fan speed constant. Or perhaps that outer race gear could be incorporated into such a mechanism. If you watch one of these closely in action (remove one from a copal shutter and work it around)...you might see what I'm saying. Would be great I think!
Oh...and you could also incorporate something like a self-timing mechanism for much longer exposure intervals.
Seems like you'd have enough room on the flat of that plate surrounding the lens for something like this. What do you think?
At any rate...its so very exciting to see that you are re-creating such a fascinating lens! (I want one!) Good luck!
Re: New 75mm Hypergon Lens
ps...a much simpler mechanism would be to attach "fan blades" to the outside of that circular race...and position an air tube near this to blow the fan around - much like the original. Could go either way I guess...but I like the idea of the spring driven model - would be more accurate and adjustable for different time intervals.
Oh...and in either case - of course, as in the original fan, the "axis" needs to be off center (so as not to compromise the image), and the rotating area of this "axis" needs to be figured into the ND forumula.
Re: New 75mm Hypergon Lens
Nice job! What do you mean for that 500$ as a final price?
Looking forward for updates
Re: New 75mm Hypergon Lens
Also looking forward for updates... I assume for 8x10 format?
Re: New 75mm Hypergon Lens
Is this the same lens Jason posted in another thread a few months ago?
https://www.largeformatphotography.i...light=Hypergon
Re: New 75mm Hypergon Lens
Drool.... This looks great. Keep us informed. Please...
Re: New 75mm Hypergon Lens
Does anyone understand how the 'fan' worked on the original Hypergon ?
I have wondered about this for years. Surely the pupil size is so small ( ~2mm ) that you could not avoid having a black spot in the centre of the image ?
Re: New 75mm Hypergon Lens
Quote:
Originally Posted by
Mark J
Does anyone understand how the 'fan' worked on the original Hypergon ?
I have wondered about this for years. Surely the pupil size is so small ( ~2mm ) that you could not avoid having a black spot in the centre of the image ?
The fan spins for most of the exposure time, exposing the outside area of the film/plate. It swings out of the way at the end of the exposure to expose the center. The recommendation is for the exposure time without the fan to be 1/8 of the exposure time with the fan, but that of course depends on the reciprocity failure rate of the film/plate.
The fan-equipped Hypergon was made prior to the invention of center filters, which might be a more practical solution today.
Re: New 75mm Hypergon Lens
Quote:
Originally Posted by
Mark Sawyer
The fan-equipped Hypergon was made prior to the invention of center filters, which might be a more practical solution today.
Hmm. The VM, not always a reliable source, says that the Hypergon was invented, or perhaps came to market, in 1900. By 1912 Rodenstock cataloged a sort of competitor, the Pantogonal, which covers 125 -130 degrees. R'stock offered a center filter, the Enixantos, for the Pantogonal and touted it as superior to "bunglesome and complicated appliances usually found on extreme angle lenses." Someone recognized optical CF's advantages over mechanical ones almost from the beginning.