Well that was awesomely thorough man, and looks a lot like what I was sketching out. I'll take a crack at it in Illustrator. Hopefully I can post some results in a week or two. Lenses are going to be the trickiest, but maybe I can screw in some of my older lenses, that use threads instead of a locking ring to attach to the body.
On Wed, Dec 30, 2015 at 12:48 PM Focal Camera <email obscured>> wrote: > Hey John! > > So far not, but it's also currently not set up in a good way for that I > believe (i.e. fixed website). I already have a wiki up and running on the > same server but still need to transfer the information. This way it should > be possible for people to easily upload new modules as well as variations. > > I've owned a 617SIII in the past (By sheer dumb luck, could never afford > that if I had to buy one!) and they're quite a thing indeed, but I was > surprised at the simplicity of the thing (Compared to say, the Fuji 617 > cameras). Making a 6x17 film back should be relatively straight forward. > When I designed the current iteration of the film back I kept in mind that > people might want to do wider formats. > > It might however be simpler if you go to 6x18, which is double 6x9, due to > the film frame numbers on the back of the 120 film. It has numbers for both > 6x4.5, 6x6 and 6x9. If you use the 6x9 numbers by moving the red window on > the back lower or higher so it shows those numbers, you could double-up > them for frame advances (i.e. at the start advance to frame 2 and go to 4 > from there and so forth). > > You take a 6x6 standard back file and look for all the horizontal parts. > The vertical parts should be fine as-is. Each horizontal part can be split > right down the middle. You then add the desired length to go from 6x6 to > 6x18 (thus 18cm). The only part that you don't cut fully is the top inner > plate with the spring for the film ratchet gear. This one you only cut the > two outer lines of the part so that the spring now rather than seeming > centered will be on the right side of the part. > > For extra stability you could add a few more notches to reinforce the extra > length. The film pressure plate would also benefit from some more strength > compared to the smaller format, so it would help cutting those out of > something like acrylic (Possibly Delrin? Never tried). The idea is that > these springs are a little thicker than the space they actually occupy, > meaning they will always be in a slightly compressed state when film is > present, thus keeping pressure. You can also increase the thickness of the > springs to add more pressure here. > > The front of the camera would now no longer have the standard square > mounting brackets that the 6x6 back had, so no modules can be attached. > What you could do is make a cone alike the 6x17 cameras (If you see them > without the lens attached it would look identical to a 6x18 back I just > described) by having a top and bottom plate looking like this (Here's to > hoping my bad ascii art will come across right) > ______________ > / \ > / \ > / \ > / \ > |___________________| > > And side plates that would lock onto the sides of that, connecting at an > angle with the film back. You could even add a tripod connection on the > bottom plate (Quite easy to do! If you want I can send some prototype files > for a tripod adapter I'm working on). The front of this trapezoid could > have the square mounting brackets for other modules so you can attach a > shutter and a lens. The length (Or height rather) of the trapezoid would be > dependent on your lens. > > Lens wise you could either go for a pinhole which could cover that (but > boring), an existing lens (Something like a Super Angulon 90mm f8) that you > can set at the right distance for a good focus range (The lens adapter > boards module has one that will fit this lens) or make your own. > > Making your own can be simple or tricky depending on your desire. Creating > a long lens (200-250mm and up) can be done with ease, making a wide angle > (150mm and down) can be tricky. For a longer lens you could achieve quite > good results by going for a achromat of the right focal length (Or longer) > with a smaller aperture to stop some of the abberations (Unless you want > them!). The more you step down the higher your coverage will become, too. > (On large format lenses you will often find that the specifications list > both coverage wide open and stopped down). The longer the lens, the better > the results (As you are using more of the center of the image circle). > Surplusshed has some large (400mm) achromats that could do quite well. > Since you'd be stopping it down and / or using it on a tripod, a simple > shutter (Like a removable stop without a hole) would do the trick quite > well. > > Let us know how it goes! I'd love to hear more on your lens plans. > > Cheers, > Mathijs > > On Wed, Dec 30, 2015 at 5:20 PM, johnbentcope <email obscured>> > wrote: > > > Has anybody in the community contributed to the project? Are community > > contributions welcome? > > > > I am a big fan of the format of the Linhof 617, and have been interested > > in building a homemade clone of it for some time. That's what originally > > drew me to the Focal Camera project. With the wide format of the film, > > it'll require some more planned-out optical elements to span the light > > across the full 17 centimeters, so I'm looking into that now with a local > > camera repairman. > > > > I'm wondering if information to the community about the design of the > > cameras is limited to what we can reverse engineer from the cut files. > > > > Thanks for kicking off a great project Mathijs! > > -- > > > > Read the whole topic here: Focal Camera: > > http://lurk.org/r/topic/6PmeckvMuVtZBIN00oNqNF > > > > To leave Focal Camera, email <email obscured> with the > > following email subject: unsubscribe > > > > -- > > Read the whole topic here: Focal Camera: > http://lurk.org/r/topic/6XEiKZxsZetIVgMM4WyMQj > > To leave Focal Camera, email <email obscured> with the > following email subject: unsubscribe > -- John Bent Cope