Digitizing Antique Stereo Cards: Looking for ideas on digitizing old stereo cards. I have some that are flat enough to scan but others have such a pronounced curve that they can't be...

Riggson Loc: Tucson, Az

Looking for ideas on digitizing old stereo cards. I have some that are flat enough to scan but others have such a pronounced curve that they can't be successfully scanned. From Googling a bit, I see two options:

1) Push down on the scanner cover until they flatten out. Being albumin prints, I resist doing this for worry of cracking or tearing the emulsion.In some cases there's 1/2 to 3/4 inch curve over the 3 1/2 inch height of the card.

2) Set up a copy stand with good side lighting and photograph the cards. Not sure if I can get enough depth of field to get good focus on the entire card so focus stacking might be needed.As I have a couple thousand cards that would be a major pain to photograph the entire set taking multiple exposures each and then combining the images.

The second option seems the most doable, but I'm wondering if anyone has tried this before and can share any pointers.

Architect1776 Loc: In my mind

Riggson wrote:

Looking for ideas on digitizing old stereo cards. ... (show quote)

No idea.
We use ours with the 1800's viewer as intended though.
Lots of fun and brings back childhood memories.

Riggson Loc: Tucson, Az

Architect1776 wrote:

No idea.
We use ours with the 1800's viewer as intended though.
Lots of fun and brings back childhood memories.

I also use the old Holmes viewer regularly, but as many of mine are fading with age I wanted to bring them into Photoshop and try to recover before they deteriorate even more.

Jay Pat Loc: Round Rock, Texas, USA

I would consider flattening one image, slowly.
Put a book on top of the image.
A day later or several days, add another book.
Look at the image to see how it is doing (any cracking).
If this works, try another one.
I have no idea if this will work.
Just something to try.

I enjoy looking at these stereo images and I hope you post many!
I view these images using the crossed eye technique.
Pat

Riggson Loc: Tucson, Az

Jay Pat wrote:

I would consider flattening one image, slowly.
Put a book on top of the image.
A day later or several days, add another book.
Look at the image to see how it is doing (any cracking).
If this works, try another one.
I have no idea if this will work.
Just something to try.

I enjoy looking at these stereo images and I hope you post many!
I view these images using the crossed eye technique.
Pat

Thanks for the suggestion, I may try that with a duplicate card or two.

As a bit of background, the cards were apparently produced with the curve so when they came out of the production area they could be stacked and nest together to prevent the stack from toppling over. Flattening would actually be trying to reverse part of the manufacturing process.

In libraries, they use a repro camera with a digital back, but that would be a bit too much of an investment for a home hobbyist.

alliebess Loc: suburban Philadelphia

Riggson wrote:

Thanks for the suggestion, I may try that with a duplicate card or two.

As a bit of background, the cards were apparently produced with the curve so when they came out of the production area they could be stacked and nest together to prevent the stack from toppling over. Flattening would actually be trying to reverse part of the manufacturing process.

In libraries, they use a repro camera with a digital back, but that would be a bit too much of an investment for a home hobbyist.

I believe the reason for the curved cards was to increase the 3D effect, but not sure how that works. I would be reluctant to try to flatten the cards; they have been curved for a very long time.

fetzler Loc: North West PA

Try contacting the George Eastman House in Rochester, NY. They have many experts.

You may have luck with a longer focal length macro lens at small aperture.

DWU2 Loc: Phoenix Arizona area

Riggson wrote:

Looking for ideas on digitizing old stereo cards. ... (show quote)

An untested thought - if you use method 2 and get good DOF, you'll still have distortion due to the curvature. What if you used Photoshop's Transform or Liquify features to remove some of the distortion?

Riggson Loc: Tucson, Az

alliebess wrote:

I believe the reason for the curved cards was to increase the 3D effect, but not sure how that works. I would be reluctant to try to flatten the cards; they have been curved for a very long time.

The theory is based on the optics of the old viewers. The viewers have a simple magnifying lens with some amount of field curvature in their focus (never been measured to my knowledge.) The curve of the card is presumed to match the field curvature of the lens so the entire image is reasonably well in focus.

However, a couple years ago a stereo afficianado found some old photos of the Keystone factory showing the cards being processed in tall stacks, so while compensating for the lens may be part of the reason for the curve, the old photos show keeping the stacks stable was certainly a use for the curve.

Riggson Loc: Tucson, Az

fetzler wrote:

Try contacting the George Eastman House in Rochester, NY. They have many experts.

You may have luck with a longer focal length macro lens at small aperture.

Thank you for the prompt. My copy stand is one of the old Ekatagraphic units but Eastman didn't occur to me.

ecurb Loc: Metro Chicago Area

fetzler wrote:

Try contacting the George Eastman House in Rochester, NY. They have many experts.

You may have luck with a longer focal length macro lens at small aperture.

In addition to Eastman House, check with the Conservation Department of the Newberry Library in Chicago.

HiFromSusan

Riggson wrote:

the cards were apparently produced with the curve so when they came out of the production area they could be stacked and nest together to prevent the stack from toppling over. Flattening would actually be trying to reverse part of the manufacturing process.

The curve is an integral part of the stereocard, which makers thought would enhance the 3-D view. Curved mounts weren't produced until the late 1870s. Myself, I would not want to risk damaging the mount or the emulsion by trying to flatten it.

Keeping them out of strong, harsh light will go a long way in preserving the image. Also, if storing them stacked, please do so with an acid-free separation paper between them.

Sometimes we just have to accept history, warts and all. But if there is so much distortion in your preservation shot that it seriously distorts the image, then you could always try taking several shots of the curved-mount cards, one with the top edge flat, one of the middle of the image, and another holding the bottom edge flat and then try focus stacking in post production, just a thought.

HiFromSusan

ecurb wrote:

In addition to Eastman House, check with the Conservation Department of the Newberry Library in Chicago.

That's a great suggestion. You could also try the Library of Congress. They are quite receptive to citizen-historian questions.

The Society of American Archivists used to have programs for historical society volunteers, maybe they still do. It's been a while since I attended one https://www2.archivists.org/