andrea_milano Posted February 12, 2001 Share Posted February 12, 2001 Dear all,when writing on the Gilde camera I thought of asking all inventors and innovators to come forward with their products so that more genius(I guess the correct plural is Genii) or geniuses will come forward.please do and show us what your mind and hands have produced! Link to comment Share on other sites More sharing options...
audidudi Posted February 12, 2001 Share Posted February 12, 2001 Over the past two years, I've been intermittently working on a design for a pressurized bellows that should 1) help prevent vignetting with extreme movements by forcing the bellows outward at all times, and 2) force the film flat against its pressure plate. So far, so good, but since I perceive very little market demand for such a thing, it's not a high priority hence the slow progress to date (here in Arizona, the number of rainy days we get each year is fairly small...). Link to comment Share on other sites More sharing options...
erec_grim Posted February 12, 2001 Share Posted February 12, 2001 Perhaps a genius or innovator or experienced designer could use this idea. I've been wondering whether some of the techniques used in building ultralight canoes (and kayaks, I assume) could be used to make a hybrid wood-composite camera that was lighter than traditional wood cameras, and stronger as well. <p> I am referring to the use of fiberglass, Kevlar and other materials, either by themselves or laminated with some other material, and bonded with a resin in a vacuum. <p> Wood is a nice material to work with, and looks good, but it is hygroscopic and changes dimensionally as the humidity changes (if only slightly). What is more, the joints tend to be weaker than the material itself. <p> My father-in-law, a retired engineer and whitewater canoe racer informs me that canoes used in Olympic whitewater slalom racing use this technology, and so do the most advanced (and expensive) flatwater boats used in racing and touring. However, the technology is apparently not taken as far as it could be. <p> I'd like to build my own view camera, but I wonder about the availability of such parts as a rack & pinion for focusing (and frankly, the project seems intimidating. Tho I just bought a lathe I'm no machinist, and am only a fair to middlin' weekend wood warrior.) Link to comment Share on other sites More sharing options...
audidudi Posted February 12, 2001 Share Posted February 12, 2001 Although I didn't mention it in my previous post, I have been playing around with composites, too. The tough part is making tubes but I've found a cheap solution for that: Buy a center post for one of Gitzo's CF tripods! I had previously bought a piece of CF tube that was used to make an accessory car part but picked up one of the Gitzo posts as soon as I saw my friend's new 1228 tripod. Food for thought... Link to comment Share on other sites More sharing options...
john_henderson1 Posted February 13, 2001 Share Posted February 13, 2001 I'm working on an autofocus/autoexposure 4x5 sheet film camera. Thetrick is to make the autofocus system work with tilts of the lensboard. I have three linear motors driving the lens board which isenough to move the board back and forth along the rail and to tilt andswing. I have a high resolution CCD array at the film plane. Isegment the image area and perform 2-D fast Fourier transforms (FFT)on each segment and use the results to identify the nature of theblurring and what needs to be done to correct. I then use ageneralized MINIMAX algorithm to find an optimum solution. Unfortunately, the MINIMAX routine finds a local minimum, and I'mwrestling with how to find the global solution. (For example, myMaxxum 9 has three autofocus sensors. Say an object 5 feet away iscentered on the left sensor, and an object 20 feet away is centered onthe right - which one does is focus on? [Of course, my autoLF cameracan bring them both in focus, but I'm giving a simplified example ofthe problem. In the camera-with-movements case, the problem isdetermining which plane to focus.]) I may leave it to thephotographer to get kind of close to what he wants and let the system"fine tune" the focus. But I imagine every autofocus designerwrestles with this problem. I don't know how my Minolta decides whichsensor to use or which object to focus on. Well, that's the bigproblem. I'm also performing trades on how many and what sizesegments I should take to divide up the screen. <p> The camera does do pretty good now of bringing the ground right intofocus from near to far. <p> At the moment, the whole thing is driven by my Sun workstation, but Idon't see anything that would prevent the algorithms from beingimplemented in a microcontroller should the camera go into production. <p> The CCD array also finds the darkest and lightest areas in the imageand performs the exposure analysis to ensure good exposure everytime. The computer also returns the required gamma (CI, or whateveryou want to call it) so I know how to develop the image. I guesseventually I could add an electronic shutter, but haven't botheredwith that yet. <p> I'm also thinking about an "autowind" (autoload-unload?) for sheetfilm, but haven't gotten too far with that, yet. I like to takephotos of rocket launches down here, and would like to get more thanone a launch, but those things just don't wait around for me to inserslide, remove holder, flip holder, reinsert holder, remove slide,recock, etc., etc., so I want to automate it. I like the big, sharpnegatives on my 4x5, but miss the 5.5 fps of my Minolta (oh - andautobracketing would be a natural next step - getting the correctexposure for a rocket launch is a crap shoot.) <p> Basically, I don't see why people who need or want autofocus andperfect exposure should be denied the advantages of large format suchas movements and the large negative size! Link to comment Share on other sites More sharing options...
doug_mcfarland Posted February 13, 2001 Share Posted February 13, 2001 I just finished building a prototype sheet film day lighttank that doesn't use the inversion technique. It's advantageis a smaller amount of developer required per sheet, andabsolutely no streaking or uneven development. Greatfor PMK Pyro developers (One other person has used thistechnique so far and found it gave them good results aswell). <p> After that it's on to a better archival washer - it's on thedrawing board right now and I have about 1/2 the materialneeded. Link to comment Share on other sites More sharing options...
julian_bell1 Posted February 14, 2001 Share Posted February 14, 2001 I came up with a cheap, alternative focussing system other than a rack & pinion or helix, for a 4x5 point & shoot camera. I have a rough description of it at http://job.webstar.nl/cam3pg.html Link to comment Share on other sites More sharing options...
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