Nonuniform, are you planing on using something like this: http://www.ebay.com/itm/12-NoMachine...item20d78e5e87 ?
Nonuniform, are you planing on using something like this: http://www.ebay.com/itm/12-NoMachine...item20d78e5e87 ?
“You often feel tired, not because you've done too much, but because you've done too little of what sparks a light in you.”
― Alexander Den Heijer, Nothing You Don't Already Know
If I waited for the inspiration to take decent images it'd be another year, so here are a few shots of my positioning system (notice how hard I'm trying to stay on topic?). : )
Many hours were spent trying to find a good solution to moving the film stage and I finally decided to take a chance on the IGUS Drylin rail/carriage system. I paid about 170.00 USD for two pairs of 330mm sliders. These are common amongst the video crowd and DIY'ers, to the point you can buy a set on Amazon. They are quiet and smooth, but not precise, that you have to pay for. But were they precise enough? The answer, after a few dozen scans, is yes. In practice the accuracy and repeatability of these sliders is remarkable. If you hold a set in your hand you can flex them easily along their track path. If you load it with 3.5 lbs of light source you can still flex it easily but it does not deflect all by itself it seems. I've mounted a custom GT2 belt clamp to the underside and pull them along and they work so well I'm shocked. I scanned a sheet of 4x5 film 5 times in a row and in photoshop compared the last exposure of the first run with the last exposure of the last run in difference blend mode and could not detect even a single pixel variation. So yeah, they seem to work well enough for this purpose.
Here's an image showing how I secured the two sliders mounted at 90° to each other with 4 screws. The carriage through holes are oversized and allow for fine adjustment to square up their travel relative to each other.
Here's an image of the simple belt clamp which uses a strip of acrylic with a saw kerf in it at the right height from the bottom, a scrap of the belt engages the two cut ends and screws lock it in place. Also, you can see here how it was secured to the carriage. I drilled a couple of holes through the carriage and just a bit into the belt clamp plastic as starter points (two dimples in the plastic), then finished the holes (not shown) and tapped them to receive securing screws tightened from above. Note also how it does not matter that the free pulley and motor pulley are different diameters as the drive side is kept aligned along one edge, the other side of the belt free.
The limit switches are secured to a custom mount made from plastic as well for now, they should be metal but this seems to work very well as is.
As sloppy as this may all seem to some in practice the results are amazingly good and equally amazingly repeatable. Single pixel stitching errors as well as being able to replace one set of images with another and result in visibly perfect results are easily attained. I went out on a limb with approach and it's proving to be a very viable option.
Last edited by Daniel Moore; 17-Sep-2013 at 23:24.
Thanks for the details!
“You often feel tired, not because you've done too much, but because you've done too little of what sparks a light in you.”
― Alexander Den Heijer, Nothing You Don't Already Know
Peter - I'm looking at something like this: http://www.ebay.com/itm/290776364520...84.m1438.l2649
I want the longer travel so that I can scan 8x10.
Looks great! There's no way I'm showing my control setup.
“You often feel tired, not because you've done too much, but because you've done too little of what sparks a light in you.”
― Alexander Den Heijer, Nothing You Don't Already Know
I was just wondering (as I also had in mind to build one, just dont have the time of course...)
how about using our own cameras as a stand?
It would be so simple... easy/flexible to focus, precisely adjustable in all movements (of course), light-tight etc... what we all know well.
would only need a lensboard that accepts the dslr, and to the other side the film holder which can be moved (even horizontally if the whole thing turned like that) plus a light above. This top part seems like the only tricky thing, the rest is almost "done".
I guess you must had this idea Im just wondering why this is not working?
It cannot be stable enough?
Yes, stability is paramount unless you can shoot at a very high shutter speed. For a high shutter speed you need a bright illumination source in order to dig into the dense shadow areas common with some chromes (not so bad with B&W negs which have been carefully developed to minimize high density).
Electronic flash has been considered by some here and is quite attractive if intense enough to provide a short duration flash. Focusing optics could improve the intensity of electronic flash but also increases the contrast in the copy.
The other factor with stability is the DOFocus. It is vanishingly narrow at say 1:1 reproduction ratio so the slightest motion in the setup can move you out of best focus. Just simply to capture critical focus will require a precision rack and pinion or stepper device very rigidly mounted.
Nate Potter, Austin TX., Holliston MA.
thank you Nathan, I see now better.
thats a pity we cannot benefit of what we already have.
Actually I have "built" a test version of this setup but so far only for capturing 35mm format, it worked out quite well but I was not sure this can be developed further to 4x5.. I had the same impression this might fall out because of stability problems. Also true I was capturing around 1 second each exposure at f16 thats quite long. I was using a canon 5dm2 with desktop exposure control, it was nice to focus with the live view at 100% on a big screen, though was very noisy because the high iso.
As the camera can hold stable to expose for minutes (or hours) - as we do our images with this first on the film itself- so I thought why not be as stable the opposite way?
Anyhow for me it worked for single 35mm slides, but probably there would be issues with a big moving thing on top for a 4x5 capture...
And for non price theory info thread:
http://www.instructables.com/id/Low-...mated-slide-m/
another general version of the means and method of stitch scanning.
Although, I expect, anyone seriously making one, has already done so.
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