A difficult test of Colour Negative scanning

Also featuring - Vuescan vs Silverfast vs Epson Twain




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I think a lot of serious photographers like to avoid colour negative film as much as possible. It's nasty stuff, really, although it does have its uses. In landscape photography one time when you'd be very glad to have loaded up with colour negative film is when the contrast range of the scene you're trying to shoot is huge, and you can't use neutral grey filters because you're using a rangefinder camera.



The above picture was taken on Reala 100 using the Mamiya 7II and 80mm lens, 2 seconds at f16 on a Gitzo tripod. Scanned using Vuescan and contrast, colour and levels edited fairly extensively in Photoshop. The bottom line is that the 16x12 inch print looks extremely sharp and there is no noticeable grain. It took a fair bit of work to get there, though. Check out what you get straight from Epson Twain, Vuescan and Silverfast before editing:

Epson Twain






Vuescan was set to scan Fuji Reala, first generation, which is what the film actually was. Silverfast was set to Fuji Superia 400ASA, because there was no Reala setting, and the Superia 400 setting seemed to give the closest colours to what I was trying to achieve (yes, the other options were even greener!) Epson Twain does not have different settings for different films.

All three "straight" results resemble the sort of wishy-washy dodgily coloured detritus that comes back from 1 hour labs. But as you can see, Vuescan got the closest colours, probably because it had been properly calibrated for Reala. Vuescan and Epson Twain both produce 48 bit files, whereas Silverfast only produces a 24 bit file. I thought that, seeing as I was going to do a lot of further selective adjustment to the levels of certain areas of the scan, the 48 bit files would be better. In fact a further experiment with Silverfast proves this to be a false theory. Here's why.

Silverfast 48 bit HDR colour

Silverfast gives you the option to scan in 48 bit mode, but all the adjustment tools are unavailable. What you get is a "raw" scan, straight from the scanner with no messing about. The theory is that you can edit it later with Silverfast HDR. Silverfast HDR, as I explained in my Silverfast review, is a scanner-independent version of Silverfast for working on 48 bit raw scans from your hard drive rather than straight from the scanner (hence the name HDR). The image below is the waterfall negative scanned using Silverfast HDR mode. Below that is a slide, chosen at random, also scanned in HDR mode.


My conclusion is that although the Epson has a 48 bit bandwidth, only a third or so of this is used in scanning the target negative. If the exposure could be altered, the whole 48 bit range could be made use of, but my guess is that the exposure cannot be altered. As you can see, almost the whole 48 bit range is used in scanning the slide. This explains why the Epson is much better for scanning slides than negatives. A "proper" film scanner would presumably be able to make use of its entire 48 bit bandwidth when scanning negatives by adjusting the exposure. But what this also means is that when scanning negatives Silverfast's 24 bit output files contain every bit as much information as Epson Twain and Vuescan's 48 bit files. That's because when Silverfast is used in 24 bit mode, the information which is crammed into left hand side of the histogram shown above in the raw scan is "stretched out" to fit the whole 24 bits, or 48 bits, as the case may be. Epson Twain and Vuescan do the same sort of stretching out, so their 48 bit files would contain no more information than the 24 bit ones in the same way that a 300dpi scan interpolated to 1200dpi does not contain any more information than a 300dpi scan interpolated to 600dpi. It just takes up more hard drive space and makes Photoshop slower!

Having said that, I still managed to get a very good print from my negative. So the Epson is, it seems, good enough for my purposes even for a very tricky negative like this. But presumably a dedicated film scanner would be able to do a noticeably better job. With such a film scanner, there might be a genuine advantage to Vuescan's 48 bit output as opposed to Silverfast's 24 bits.

A full review of Vuescan will follow soon.

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