For cinematography they are using a log interpretation of exposure to achieve a DR on the order of 14 stops (there's a whitepaper on Sony's site with the math). Perhaps something like that could be employed to take advantage of the HDR results.
For cinematography they are using a log interpretation of exposure to achieve a DR on the order of 14 stops (there's a whitepaper on Sony's site with the math). Perhaps something like that could be employed to take advantage of the HDR results.
Peter, I'd guess the exposures would be pretty consistent if the flash is in a fully manual mode and the flash is allowed to fully recycle.
What if there were 2 parts, a bridge to hold the camera and a light box. They would both placed on a flat surface like a piece of glass (not included).
The light box would have wheels and motors within, it would scoot itself around the surface like one of those robot vacuum cleaners. There would be no external drive rods and assemblies.
The downside of this is lack of precision in locating the light box. We agree that the precise X Y location isn't important.
But what about rotational/alignment precision? If the robot light box doesn't stay aligned precisely North-South-East-West, will the software be able to correct for this when stitching without degrading the image?
(To minimize the need for mechanical precision and put the burden on computation would be nice.)
...Mike
Thousands of people build their own cars every year, to get something better/different than what a manufacturer offers. Superperformance is the leader in this. A fully crowdsourced car is the new LM Rally Fighter, where you go to the factory and help build your own car. http://www.rallyfighter.com/buy-a-rally-fighter. Factory Five and Solidworks had a crowdsourced design project as well for a less expensive car. http://grassrootsmotorsports.com/design/Originally Posted by Ed Kelsey
When international conglomerates don't build what is needed, slightly crazy people find a way.
Nothing new about that....http://www.flickr.com/photos/michael...os/3380579654/
One man's Mede is another man's Persian.
Let's talk about goals. Here are some suggested ones:
1) High Quality, with the resolution of a pro flatbed but greater dynamic range.
2) Low price.
3) Ease of construction.
4) Ease of use.
5) Scalability.
The targeted user would be people like us: Film using photographers who can't afford or justify buying a good drum scanner.
I'll build a prototype using a PB-4 bellows, 80mm Rodagon, Portatrace light box, Nikon D200, because that's what I have.
It will be a table top device. There will be a camera support structure made out of wood, basically a thick beam supported by columns on both ends, like an upside down U. The PB-4 macro rail will be bolted to the cross beam. The light box will sit on the table underneath the support structure. Above the light box, there will be a thick piece of glass. I'll build a frame for the glass, such that three bolts can be used to adjust it's alignment. [The bellows will be aligned by pivoting it on it's mounting screw, and then the the glass table will adjusted to be parallel to the front of the lens. I'll use a Screen clam shell negative holder, which will be set on the glass, and various opaque masks will be used.
Some of the quality bottle necks will be:
A) The precision of the bellows, i.e. is the front perfectly square to the back.
B) The lens. Unfortunately, I no longer have a quality 50mm enlarging lens, at least I don't with a 39mm thread. I do have a bunch of other medium format and large format enlarging lenses, but I expect that the best performance would be with a 50mm f2.8 6 or 7 element design. My 80mm Rodagon, a fixed aperture lens, was designed, I think, for best performance at 1:1, which should be pretty close to what we need for LF scanning.
c) My ability to focus. Unfortunately, my D200 doesn't have live view, especially the ability to use live view while tethered to a computer. This would be a good use for D90 and D300s, as they allow live view.
d) The light source is visibly uneven, but we only need to use a small section of it. It should be good enough for a proof-of-concept.
“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
Do it!
Just wondering...what bellows are available for Canons?
There are two types of Canon bellows, with and without circuitry for the aperture. The former is pretty spendy and available from B&H. Latter is less than $100 and can be found on Amazon. I'll be testing a macro lens so I don't need bellows up to 1:1 and have extension tubes for slightly over that. If you do go with bellows you can pick up an old Micro Nikkor and use with an adapter, or use a microscope objective as previously described. q.v. photomacrography.net for good info.
At 1:1, using a 30% overlap, with a sensor in a Canon 7D, I'd estimate it would take about 80 exposures to cover a single 4x5. That seems like oversampling a tad. Raw is 14 bit. I haven't tested my macro lens yet to see what resolution to expect.
Oh boy, 80? That would almost be as tedious as making a profile with a Spyder3Print! Hopefully, the needed amount of sampling sites will be lower.
Macro lenses are also a good idea. I do have a couple of Nikon ones, a 55mm and a105mm, and I can test those as well.
“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
Transferring a portion of a transparency to a sensor through a macro lens has been done by many people including me. It is a sort of academic exercise now in that it can be done at high resolution with a top quality lens. The lens is the limiting factor in the detail that gets resolved. The choice is in the degree of magnification that one chooses. At 1 to 1 and smaller the resolution is set by the sensor. At higher magnification the resolution limit is set by the resolving power of the lens. As magnification is increased of course the field of view is decreased so more frames are required to cover the film. Even the best macro lenses will have difficulty in achieving an airy disc image as small as the 3 um or so that a good Aztec is capable of.
Of considerable interest is the type of back illumination that one might choose. That can be all the way from a diffused source to a highly collimated source. It only needs to cover the field of view of the objective if it moves in synchrony with the lens (as someone suggested above). A collimated backlight has the advantage of providing much less light scattering so higher contrast image transfer and more grain imaging than a diffuse source. An adjustable light source might be quite handy.
Dynamic range is limited by that of the sensor regardless of what is on film, until the film range falls below that of the sensor. For large film dynamic ranges one could employ digital HDR techniques already mentioned.
Nate Potter, Austin TX.
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