How does a film scanner work?

[d_price]

Sorry if the question is a bit redundant, but I haven't been able to

find a good answer. I want to buy a good film scanner, but I'm trying

to stay near the $600 mark. I need to be able to scan negs and

slides. I understand that a scanner can just read a slide and

determine correct colors, but how does the scanner know the "proper"

colors when it scans a negative? I know, it may sound foolish, but

wouldn't the manner in which the scanner does this determine the

quality of the scan?

[steve_dunn2]

<p>Some scanner software has profiles of various films, so you tell it what film you're using and it knows what colour the base is (as well as other details about the film's colour reproduction). Other scanner software doesn't, which makes your question quite a good one.</p>

 

<p>I've been using a Canon CanoScan FS2710 for the last few years. It doesn't have film profiles, and I can tell you that it doesn't always nail the colours. It would be nice if it did, so that I never had to try to get the right colour balance manually, as I'm not an expert at that. My guess is that it looks for the lightest part of the frame and assumes that it's pure white, and therefore uses that colour as the base colour to be removed from every pixel. But that's just a guess.</p>

 

<p>There are third-party alternatives to the scanner software that ships with a lot of scanners, with <a href="http://www.hamrick.com/vsm.html" target="_blank">Vuescan</a> probably being the most widely recommended. Vuescan has profiles for a number of films, but not all films, so it doesn't entirely resolve this issue.</p>

[steven_clark]

Yes. How the scanner interprets the color often depends on the software controlling the scanner. Vuescan or Silverfast often do a better job than the manufacturer's original for example because they tend to have a variety of film types to select from.

[john_shriver]

The scanner doesn't really know the colors, or get the "proper". I promise you, Kodakchrome and Ektachrome don't come out looking like the slide with the default settings either! This is because our eyes have one spectral sensitivity, the scanners color filters have another set of spectral sensitivities, the light sources in some scanners are very narrowband (like the Coolscans' LEDs), and the dyes in each film have different specrtal characteristics. So you have to make "corrections".

 

For a negative, one is starting with inversion, they are just "color" negatives. But the orange mask also has to be subtracted out. Look at a Kodak color negative data sheet -- the densities of the three dye layers are just different.

 

What's harder with negatives is that you, the user, are flying blind, you don't have the colors in the slide to try and match on your monitor.

[d_price]

Wouldn't all these issues make you shy away from shooting print film? Is there a scanner that actually does a really good job at this? Mabye one that has very good software, and scans well? Seems like the Konica-Minolta and the Nikon scanners are the best, but I haven't had a chance to shop around enough yet.

[steve_dunn2]

<p>One of the advantages of scanning negatives, as opposed to slides, is the lower density range of negs. Not all scanners can handle the full density range of slides, leading to lost highlight and/or shadow detail. It's much easier to get all of the highlight and shadow detail out of a negative.</p>

 

<p>As for colour balance, well, you're not going to scan it directly to disk and call it a finished product anyway; no matter what, you're going to work on it with your favourite image editing program. So you just have an extra step of trying to get the colour balance right. I find it hard to get it exactly right but not too difficult to get close, and as I'm not trying to sell my images or anything, I can get close enough for my purposes.</p>

[michael_beckmann]

D Price,

 

no this does not scare me away from using color negative film.

 

First of all, the Nikon Coolscan 5000 that I use gives me quite good results from negatives without manual intervention.

 

Second, I work on all scans in Photoshop, whether they are from slides or from negatives, to improve the color.

 

Third, I often scan very old slides which have developed a color cast over time, or they weren't neutral in the beginning due to shortcomings of the technology of the day. So they need some intensive care anyway...

 

All in all, it is nice to scan new slide film, because the colors are close to what I want, but all in all, it's not a big benefit compared to scanning negatives, and negatives have the advantage of greater exposure latitude.

[albert lui]

My favorite method for color correction is to set a midtone gray to neutral (identical values for R, G, B), if I'm fortunate to have that in my picture. The color balance will be generally correct after setting the midtone gray.

 

If the image doesn't have a neutral gray, than I'll use a photo CD image (made during film processing) for color reference. The Frontier scanner is more sophisticated than a home unit and the color balance is almost always better than the straight output from a home unit.

[d_price]

Thanks guys, I really appreciate it. You've alleviated my fears and addressed all my concerns. I can shop with more confidence now. I think that I'm leaning toward the Nikon CoolScan 5000 also, so I'll do more research on it. This is my first film scanner purchase, so is there anything that you guys suggest that I look for, things that if you could do over again, that you would?

[john_shriver]

If you can afford the CoolScan 5000, you will not be unhappy with it. It's a big step up in price to get better results.

 

If you are in the USA, DO buy one that is imported by Nikon USA. Don't buy grey market CoolScans in the USA, Nikon USA will refuse to repair them for any amount of money. You will have to ship grey market ones back to the country of origin for any repairs. While I think this is very heavy-handed of Nikon USA, it's the price Americans pay for being in a "wealthy" country.

[gee_willikers]

I just got the PrimeFilm 3650U. It looks pretty good on the screen. I have a few images I'm going to compare from a scan done on a Noritsu 3111. I'm going to compare two 8x12 glossy prints with a loupe.

[d_price]

I'll be sure to do that John. Gee who makes that scanner?