Kirk has a point, but a stitcher with specific knowledge of the application will do better. For example, dust would be a natural way to connect images.
Kirk has a point, but a stitcher with specific knowledge of the application will do better. For example, dust would be a natural way to connect images.
Vibration: Sequence is photo, move then stop, photo, etc. There is no movement vibration, and, hey, stop shaking that table!
Stitching: This isn't random. Stitching software has a problem because it has to join up a number of unknown sequences, while these sequences are known. X across, Y down, all known. This makes things much easier.
Why not a scanning back: the cheapest back from Betterlight is $6,500 for an 18Mp back. Canon Rebel T3 is $500 (12.2Mp), Sony Alpha DSLR-SLT-A33 is $480 (14.2Mp), Nikon D3000 is $500 (10.2Mp). All have macro lenses available, and there's extension tubes for the Canon and Nikon cameras.
Why not dump all the film gear and go digital: Uh, hello, anybody read Tim Parkin's comparison of 8x10 to MF digital? 80Mp is not enough for me. Blow it.
Here's the problems of using a digital camera to scan the negatives: Aliasing and the Bayer filter. It would takes something like Hasselblad's new "200Mp" camera with the moving sensor to overcome this. No consumer stepper motor is going to be moving one sensor pixel in position. Look at the comparison (link) and tell me it's kicking ass even on the Mamiya 7 on that resolution chart. It is going into distortion before it hits the 6 mark.
"It's the way to educate your eyes. Stare. Pry, listen, eavesdrop. Die knowing something. You are not here long." - Walker Evans
Ben, no offense, but this tiny factual mistake set off a series of observations that would not be needed with a few careful tests. My camera is a 5D, not a 5DII. The sensel size is 8 microns. That's 125 sensels/mm, which can record half that at best (60 lines/mm), and that's only in the horizontal and vertical directions. That's my 1600. Yes, it might be less, but it certainly will not be more. The point was that a 13 megapixel camera isn't going to out-resolve an Epson at 1:1, no matter how sharp the pixels are or are not, or how sharp the lens is. It will take much higher magnification, which will require a different lens arrangement and more challenging mechanics.Originally Posted by Ben Syverson
A sensor with twice the density won't help, if the lens can't keep up with it.
Gotta travel now, but I have the camera, the lens, the negative, and the light table. Maybe modest, yes, but that's what I have and I can't afford to replace it. This weekend, hopefully, I'll put a data point out there.
Rick "gotta run" Denney
Rick, at 60 lp/mm the contrast of the Epson is piss poor. See somewhere here a plot I made of the Epson 750 of resolution vs contrast. IIRC at about 60 lp/mm (I think I went up that high) the contrast was below even 5%. The digital equivalent would be much much higher especially with premium optics. Additionally one can play with the illumination source and use one highly collimated to further enhance contrast in the copy, a feature not available for the Epson. I found it! Rick per below. Actually I see the contrast is about 0 at 60 lp/mm, so pretty much useless while the DSLR is vastly superior (not counting field of view of course).
Nate Potter, Austin TX.
EPSONcont-web-1 by hypolimnas, on Flickr
Here's a dynamic range test. I hope that's the right term. Please remember that I was a liberal arts major. I photographed a Stouffer 31 step step wedge on a Portatrace light box with a d200 and a 105mm Nikkor AF-D Micro lens. F-stop was f5. This is only meant to test how my equipment will see density with one exposure. The raw file was processed in Lightroom. All of the density/contrast settings were zero. I added what the eyedropper in Photoshop told me the LAB L channel values were and also visual density numbers from my x-rite densitometer.
Next is 3 exposures, 1 stop apart. I used Photomatix's tone compressor to tone map the HDR file. Obviously, there's a lot of room for adjustment, and you can always take more exposures.
“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
My studio macro setup is designed to do focus stacked multirow spherical panoramas by rotating around the entrance pupil of the lens. http://img.photobucket.com/albums/v6...AutoFS_02s.jpg It can also do orthographic stitches by moving the subject.
Here's a 500 MP image created with it: http://photosynth.net/view.aspx?cid=...d-4567cfceae6a Note: Zooming all of the way in is equivalent to pixel peeping at 200%.
While this setup could probably do an 8x10 scan, it would be better to use a vertical setup. Vibration is the biggest problem to overcome. Mirror slap and shutter vibrations are the hardest to deal with. I'm using a 2 second delay to handle the mirror slap and short duration flash to handle the shutter vibrations. Currently only Canon has electronic first curtain shutter. Another option would be to use an external leaf shutter.
Off the shelf linear slides like Stackshot, http://www.cognisys-inc.com/stackshot/stackshot.php, can easily do 1 micron steps. Building a dedicated XY stage with salvaged parts from a scanner should be easy enough to do. I use an Arduino to do the focus steps and it wouldn't be very hard to update the program to control an XY stage with micron resolution. Getting it to move 1 micron without stiction (stick/slip) will be the hard part.
Optically, you'll need a lens that is sharp corner to corner, no distortion, no CA, etc. There are not many inexpensive lens that will qualify. I have a JML 21mm f/3.5 lens that would work very well, but I don't know if any are available new.
Fun! I had planned on using the t-channel aluminum extrusions for the support structure.
“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
This test is very imperfect. But for what it's worth, here is a scene photographed with a Toyo AX, 120SA, Acros, divided Pyrocat MC and scanned with a Cezanne.
The scanned file could produce a 30x40" print at 300 dpi. (Actually the final shot is cropped in a bit, and so it'd be more like 26" x 40")
Using a light box, pb-4 bellows, d200, and 80mm Rodagon, here's a shot of the bible:
This would produce a picture 8.5x11" at 300 dpi. On the negative the bible is about 5/8ths of an inch long.
Next is a crop of the adjusted Cezanne scan:
“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
Here is a close-up of the hodge-podge scanner "scan":
And here is a crop of the Cezanne scan:
Besides making correct comparisons, which I doubt that I did, the biggest challenge was focusing.
“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
This is something I too have thought about, and may give it a try at some point. After seeing all the amazing macro work done with microscope objectives I would consider using some of those for the project. There are supposedly pretty good ones that can be bought new for $60-$150, but I do not have experience using them.
Consider Nikola Rahmé's work for instance:
http://www.flickr.com/photos/eurythyrea/sets/
It seems to me that you could make this setup more rigid, and make a simple but sturdy stepper-motor controlled stage with a light source underneath it:
http://www.flickr.com/photos/eurythy...in/photostream
The biggest problem I would foresee with using these microscope objectives would be the incredibly narrow depth of field. I wonder if focus stacking software (like this guy and other macro shooters use) would be confused by the 2D surface or not?
As others pointed out, I would be worried about the stitching software being able to handle it. However that is one area of software development that seems to be progressing quite fast, and I'm guessing it will only get better and better.
Evan
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