Slide scanning Jitters

#1
I am preparing to digitally archive a large number of 35mm slides. I am learning digital film and wandering if I am expecting too much in the processing even though I am planning on using 4000dpi. I have rich and luscious content as it is in film and I am trying to anticipate what will be lost just in switching mediums.

#2 How are the slides going to be skewed if say the content is on the dark side and knowing that digitizing will loose detail there?

Hi gybmot.

Welcome to CiC. You will find this a most friendly and welcoming site just bursting with information from many professional as well as well informed amateur photographers. One thing would be nice--we like to use first names and gybmot doesn't exactly fit that category. Easy to do--just update your profile.

A lot of how your slides come out in digital format depends on several things--mainly, I've found is how good the original slide is. Also what scanner and software are you using? Some problems can be improved in processing after scanning, so don't give up hope on those not-perfect slides. You might actually be able to make them better than the original.
I would think that 4K is a bare minimum for scans. Better at 5600 or 6K.

Good meeting you Merle. Thanks for the welcome.
I am planning on using a service called Larson Digital Service. They only offer 2,3 or 4000 DPI. I might be missing somthing...
Won't they have to decide which side of the spectrum to favor when they copy the slide?

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Originally Posted by MerleP

I would think that 4K is a bare minimum for scans. Better at 5600 or 6K.

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It's going to depend on what you want to do with them; @ 4000 dpi, 1 linear inch @ 180dpi (being a good basic resolution for a not-over-the-top print) will pop out the other side at 22 inches.

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Originally Posted by gybmot

I am planning on using a service called Larson Digital Service. They only offer 2,3 or 4000 DPI. I might be missing somthing...
Won't they have to decide which side of the spectrum to favor when they copy the slide?

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Hi Tom. Good to meet you.
The DPI scan level has more to do with size of the image you get, and how you're going to treat it afterwards. I have found it nice to be able to crop some of my slide images, so scanning them at a higher rate helps. If you're scanning dark (slightly under-exposed) slides the exposure is what counts here, and is dependent on the software you are using. Many times slides that are unacceptable because of darkness can be reclaimed by scanning and increasing the exposure during scanning. I suspect your Digital Service will be able to do this for you. Good luck, Merle

Am ruminating...

Hello Tom:

To make it a little more graphic for you I scanned an old slide of mine, which is underexposed in the bottom half. First scanned at 4800, and then at 300. Both were saved as 24-bit .tif files. The first one was about 64 MB, the second was about 300 KB. This great a difference is exaggerated to easily show what happens with a low resolution scan. Obviously the difference of 1000 pix/in wouldn't be that great, but would be noticeable if you try to print it something over 4x6" Both have been manipulated to correct for aging, etc.

I've done quite a lot of film-scanning, and have found that scanning at 16-bit colour depth helps a lot - it's not disimilar to using RAW rather than Jpeg. It's not impossible to do it in 8-bit, depending on the software used but i much prefer using 16 bpc. You might ask which they use, or whether they offer the choice.

Ditto...when I scan my IR photos, it's always 16 bit and saved as a .tiff file. I always print from .tiff, never from jpeg as this picks up most all the colors the .jpeg tosses.

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Originally Posted by proseak

I've done quite a lot of film-scanning, and have found that scanning at 16-bit colour depth helps a lot - it's not disimilar to using RAW rather than Jpeg. It's not impossible to do it in 8-bit, depending on the software used but i much prefer using 16 bpc. You might ask which they use, or whether they offer the choice.

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Thanks Peter, I've always scanned in 24 bits, and have had good results. Will have to try in 16. I wonder does the scanner make a difference? Or is it something in changing from 24 to 8 bits in most software that doesn't translate well?

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Originally Posted by ChrisC

Ditto...when I scan my IR photos, it's always 16 bit and saved as a .tiff file. I always print from .tiff, never from jpeg as this picks up most all the colors the .jpeg tosses.

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Agree--tiff files print much better.

When I say scanning at 16-bit, I mean 16-bit per colour, or channel, if you prefer. This results in a 48-bit image. Scanning at 24-bit is scanning at 8-bit per colour/channel.

The advantages are similar to RAW over jpeg - you get to choose how the tones are mapped, before going to 8-bit for output.

I suggest that you take a look at LaserSoft Imaging and SilverFast, their suite of scanning software packages offer an impressive collection of features including IR channel scratch removal, multi-pass scans for HDR imaging with digital noise reduction.

Their SilverFast HDR Studio is what I'll be adding to my film PP flow.

...and there's always Vuescan - $40 well spent!

http://www.hamrick.com/