scanning with dslr?

[sanking]

Although I have never done this it would appear to be a doable proposition. Color can be controlled by the light source, problems of contrast could be handled by HDR, and you keep the camera stationary and use some kind of mechanism to place successive shots in exactly the same plane of focus and position relative to the lens.

Could this equal a drum scan? It might come close, but you would have to make many shots and spend a fair amount of time stitching. For comparison, most would agree that the absolute maximum one could get from a sheet of 4X5 film B&W film is a file size of 320 mp, which you would get by scanning 4X5 with a 4000 spi Howtek drum scanner. If you started with a 10mp Canon 40D, and assume loss of 35% for each shot necessary for stitching, you would need a minum of 50 shots of about 6.5 mp to equal 320 mp, or 150 shots if you used the three shoe AEB bracketing of the 40D.

A far more realistic scenario results if you make the assumption, pretty sound, that a sheet of 4X5 does not have more useful information than 2000 spi, which gives a file size of 80 mp. That you could get with the 40D with a mere 12 shots, again taking into consideration loss of about 35% for stitching. Multiply that by 3 for AEB bracketing and you are up to a total of 36 shots.

Either way there is a fair amount of work involved.

Sandy King

[Darin Boville]

>>Either way there is a fair amount of work involved.<<

Just a note. I use Autopano Pro stitching software and have had great luck with it. It can be highly automated--you can even dump a pile of images into a folder and it will find the panos automatically.

With a properly made jig, and assuming the color and contrast problems can be resolved, it should take no more than ten minutes to shoot an image. Probably much faster after getting used to it.

Another thought is that you wouldn't have to equal a high end drum scan to consider this idea a success. Simply narrowing the gap would make this an attractive proposition, especially considering the cost savings.

--Darin

[AJSJones]

>>Either way there is a fair amount of work involved.<<

Just a note. I use Autopano Pro stitching software and have had great luck with it. It can be highly automated--you can even dump a pile of images into a folder and it will find the panos automatically.

With a properly made jig, and assuming the color and contrast problems can be resolved, it should take no more than ten minutes to shoot an image. Probably much faster after getting used to it.

Another thought is that you wouldn't have to equal a high end drum scan to consider this idea a success. Simply narrowing the gap would make this an attractive proposition, especially considering the cost savings.

--Darin

The 6"x6" xy focusing rail is only $35 and the LitePad (or cheaper alternative) could be used to create a custom WB and an image made of it with no film to create a mask for use on PS to even out illumination. Most DSLRs today have a DR of >8stops - good enough for transparencies without HDR. The 5D2 has 21 MP so using as little as a 10-15% overlap (with good stitchers) a 3x2 stitch could get you over 100MP. There's a separate ongoing discussion (not for this thread) about how much more than that you can really get from a 4x5 but even a 3x4 stitch will get you over 200 MP. With a workflow set up in PS and a decent computer and marks on the XY scales, this is beginning to look like not so much of a pain after all. Need a good lens, however For another section of the forum!

[Ben Syverson]

What 6x6" xy focusing rail is $35?

[Ben Syverson]

Cheapest thing I can find is this thing from Adorama for $174

Edit: Oh, okay, I gotcha. Nevermind! $35 + shipping ($50 total) it is.

Edit 2: Okay, I'll bite. I have one on order. When it arrives from China, I'll give it a whirl on a 4x5 and see how it does compared to the Epson.

[Ben Syverson]

Some notes to myself regarding this project.

Desired final file size: 10000 x 8000 (2000 DPI)
Canon 5D Mk II minus 30%H x 25%V overlap = one-shot pixel dimension of ~4000 x 3000
Number of passes: 3 x 3

Nine images isn't too bad.

[AJSJones]

Cheapest thing I can find is this thing from Adorama for $174

Edit: Oh, okay, I gotcha. Nevermind! $35 + shipping ($50 total) it is.

Edit 2: Okay, I'll bite. I have one on order. When it arrives from China, I'll give it a whirl on a 4x5 and see how it does compared to the Epson.

Great! May not be the sturdiest XY system for heavy-duty field work and a 10lb camera rig but it should hold a small lightpad* Don't forget that with LiveView10X focusing on the 5D2 should be superb (no shims required I'll be interested in how you do, so please report back


* My earlier post was for a bright HO LED panel that was $150 although there's the older model at $130; but search *Bay for "Mini light box light panel" - I have one from Visual Plus and in the central 4x5 area the gray values ranged from 52-58% so not great but not bad for $30 +$17 shipping from HK but there may be other sellers and be able to move it around easily. For flat stitches like this, I think a good flatfield lens should not require the regular 30% overlap, but 9-12 images should be great.

[Mick Noordewier]

For b/w this seems straightforward. How will you handle inversion for color negs (orange cast removal, color cross-over, etc)?

[AJSJones]

I'd get out my Photoshop manual to see how to subtract the orange and then maybe invert and then ...




... ask for help
(luckily all my needs are transparencies so I won't have to solve that for myself )

[Mick Noordewier]

Yeah, pretty much my thinking also. Here's an example of the manual approach:

http://www.flickr.com/photos/pinkhea...216070/detail/

Not very automated. Also, skin tones are much more problematic in my experience. There are some PS plugins floating around (e.g. NegPos), but they don't seem to be for current PS versions.

VueScan does a very nice job. Perhaps a stitched file could be created that VueScan would consider a "raw" file, and then process as if it had been created by the scanner.