Scanning Glass Plate negatives

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Big Fish
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Scanning Glass Plate negatives

Postby Big Fish » Thu Oct 23, 2008 6:55 pm

I want to scan glass plate negatives(from circa 1900), restore and print high quality 30 x 40 prints using an Epson 9880 The negative sizes are 5 x 7 and 4 x 5 in very good condition. I am using an Epson 750 with Silverfast 6 with PS CS2 or PS Elements 5.To be brief, instead of questions and answers, can someone walk me through this in this forum. Thanks.

LSI_Morales
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Re: Scanning Glass Plate negatives

Postby LSI_Morales » Fri Oct 31, 2008 12:26 pm

Dear Big Fish,

Although we do not have any glass plates here (we have never scanned plates), you should consider a few things before starting your job.

The first thing you have to have in mind is those glass plates are very delicate, and after century even if they seem to be in very good condition they can be damaged easily.
You will need a transparency unit, which means that you can also scratch and ruin the surface of the scanner (in this case any of both glasses appart from your negative)
Some people recommend to use some sort of "spacers" made of cardboard to avoid this risk, however while doing so might work for some people, you will be faced with the next problem.
The focus in many flatbed scanners is very limited (very shallow depth of field) and mostly automatic, this means you can not adjust the focusing point, since the glass (your negative) is thicker than modern negatives or slides, it might easily fall out of the focusing range of the scanner (especially if you use the spacers to prevent the previous problem).

The last problem is refraction of light, every time the light of the scanner goes throug a glass surface it will undergo some kind of refraction which can produce many different kinds of optical effects, aberrations, etc. The refraction of the glass included with the scanner is controled by the scanner manufacturer but since you are adding a third glass surface and thickness to the equation, this might lead to undesired effects, especially if you have into account the previous issues.

I would suggest you make your scanns as 48 bits HDR color (RAW files) to be corrected later in postproduction, in that way you will have an unmodified negative (exactly like the original), also make two different scans (one for each side of the glass), perhaps one side will be more effective than the other side of the glass.

And if you happen to have a scanner with shallow "DoF" then probably you might have focusing problems, if that is the case you might have to try with a different scanner.

Thanks for your interest

Have a nice day
Alejandro Morales

LaserSoft Imaging
Media manager, Software testing

Big Fish
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Re: Scanning Glass Plate negatives

Postby Big Fish » Sun Nov 02, 2008 8:04 pm

Alejandro...

Thank you for your response. Yes, I have made my own template for holding the various sizes plate out of 1/16" black cardboard stock which seems to stay in the focual range for a 1/16" and 1/18" plate. I also have a piece of mylar in case I need it however, I am very careful about placing plates on scanner. I am aware of the KAMI solution but would not use on actual plates. However, I do have 8 x 10 copy negs of some plates that I may try KAMI fluid. Some of the plates are "wet" but most are "dry" and because of the age vary in exposure, contrast and deterioration. However, your suggestion of scanning at 48 bit HDR was extremely helpful. Depending on the plate it works both with 48 bit HDR color and 16 bit HDR greyscale. What also makes a big difference is playing with negafix. Originally, I selected Kodak and Plus-x because of the age of the plate and evaluating the negative. However, the Afga Ultra proved to very interesting adding contract, depth of tonal range and warmth to image. Also, Kodak with Gold-100 was more attractive than plus-x. Perulta was also interesting. I took one detriorated plate and one excellent condition plate and following you suggesstion was able to improve both especially the detriorated plates when I tweaked in Photoshop. I am fortunate to have large exhibition silver gelatin prints to use as a baseline. I will continue to experiment and post here. I have another question I will post seperately.
Again, thanks.

LSI_Morales
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Re: Scanning Glass Plate negatives

Postby LSI_Morales » Mon Nov 03, 2008 11:41 am

Dear Big Fish

I am glad you could get some of those plates correctly scanned. It would be interesting to see the results, if you happen to post any of those online, please send the links.

Thank you

Best regards
Alejandro Morales

LaserSoft Imaging
Media manager, Software testing

Big Fish
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Re: Scanning Glass Plate negatives

Postby Big Fish » Mon Nov 03, 2008 10:48 pm

Thanks again. I am hoping to set up a website by the end of the year and will keep you posted.

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RAG
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Re: Scanning Glass Plate negatives

Postby RAG » Tue Nov 04, 2008 6:48 pm

Hey,

Something you might try to increase the dynamic range is to do three 16bit Colour HDR scans. One bright to get the shadow detail, one with the tonality adjusted for the mid-tones, and one adjusted for the highlights. Then you can try out the merge HDR feature in Photoshop.

By the way the general recommendation is to scan B&W in colour mode because you get three channels of data Vs the one you get when you scan in grayscale.
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Big Fish
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Re: Scanning Glass Plate negatives

Postby Big Fish » Wed Nov 05, 2008 5:29 pm

RAG...

Thanks again. I will try your suggestion however, I have not used the merge tool on PS. Also,I am also finding that it is a bit easier to work with the sepia toning in Light Room. I have 1.4 and it dooesn't appear that it has changed much in LR 2. It all personal and relative but I come the old school of wet sepia toning and liked the (silver gelatin) prints with a warm light brown tone.

I will keep posting results. Many appreciations for your information.

Big Fish

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RAG
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Re: Scanning Glass Plate negatives

Postby RAG » Thu Nov 06, 2008 6:49 pm

Lightroom is awesome! PS CS4's new camera RAW has adopted some of the same features found in Lightroom for making non-destructive tonality adjustments.
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Big Fish
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Re: Scanning Glass Plate negatives

Postby Big Fish » Sun Dec 14, 2008 9:53 pm

Thanks RAG...

I have been trying some other scanning methods which were a bit simplier for me to try . Following another suggestion I recently scanned the glass plate emulsion down on the platen at 48 bit color and one scan at 48 HDR color at 2.5. I scanned one used SFAI which was more difficault for me to use and one with Epson scan. I did not know how to save the SFAI file to a folder or PS however, the scanned image looked very similar to the 750 Epson Scan. There's some contrast, dust removal and spotting work but the information looks very great...sharp with detail.

I would like to try your last suggestion of doing three scans to see if the scan can be perfected further. However, I am a bit unfamiliar with SFI, saving the 3 files and photo merging them in PS. In the gradation menu, how do I scan one for brightness, mid tone and shadows and save them. As a baseline setting, at what numbers to I set L, contrasts, brightness, shadows, etc, tolerance? What about color correction? I would like to be more profient in SFI as it seems like a great imaging tool.

I have started paper selection and done a few tests which are also looking very good. Just trying to get a master file completed. Any guidance is greatly appreciated.

Best Regards,

Big Fish


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