Flatbed vs drum scan

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Hi,

Would someone please tell me if flatbed scan of large format B/W photographs is as good as or even better than drum scan? If flatbed is recommended, what type? Also, what resolution do I need for scanning of 1:1 high quality reproduction? Is color scan recommended or duo/Tritone, etc.?

This is rather new to me. Your response will be helpful.

Many Thanks,

Aaron

-- Aaron Ng (ngaaron@singnet.com.sg), July 19, 2001

Answers

Hi Aaron, let me start with the remark that it will be pretty hard to find a person in Singapore who is capable of producing a decent drum scan. I had the same problem you mention, and will stick with a 4x5 inch Pro Photo CD scan. Having said that, a 4x5 inch drumscan of a negative or slide (as opposed to "photograph" you mentioned) is by right "better" than a flat bed scan. However, it all depends on the purpose of your final product. Do you require a tack sharp huge enlargement (remember the Louis Vuitton banner on Ngee Ann City a few months ago), than a drum scan is required. It will set you back around USD 100 per scan. For anything else, up to say A1 format, a high quality flatbed scan of your slide/negative should do. A 4x5 inch slide scanned at 1500 dpi will provide you a 20x25 inch result at 300 dpi! Another thing to consider is D-Max which is practically the contrast range of the scanned file. Any flatbed scanner that scans on a dynamic range of more than 3.5 (5 is max) should do. Also note that the scanner should be able to scan your 4x5 inch slide/neg at an adequate optical resolution; it should not interpolate its files.

Cheers,

Mark

-- Mark Houtzager (markhout@magix.com.sg), July 19, 2001.


Although good drum scans will always beat good flatbed scans, there was a very interesting discussion on the Piezography 3000 user group a month or two back on how best to maximize flatbed scans. The consensus seemed to be that by using Kami mounting fluid on a good flatbed (such as the Epson 1680 series) with good software (like Silverfast) and when using large format (4 x 5 or larger) one can approach drum scan quality. You should probably find the user group (on Yahoo groups) and search through the archives.

-- Howard Slavitt (info@enaturephoto.com), July 19, 2001.

the principal difference between the results you get from a $50,000 drum scanner and a $350 Epson scanner are (1) sharpness and (2) shadow detail. if you are going to all the effort to shoot 4x5's with decent equipment, then using an Epson flatbed scanner for your printing is like putting a vaseline-smeared plastic filter over your schneider lens.

there are some good flatbed scanners out there (one of the best is made by Scitex, and it costs something like $7000), but please don't be fooled by the apparently good results you get from a $350 Epson scanner-- they look great on your screen, but if you compare apples to apples at 100%, you'll realize that using a cheap flatbed scanner is no substitute.

of course, it is also important what your final results are intended to be. if you are scanning for the web, you will get just as good results with a cheap scanner as you would with a drum scanner. but if you're printing, even fairly small prints, then there really is no comparison.

-- chris jordan (cjordan@yarmuth.com), July 19, 2001.


I've tried the Kami on Epson 1680 technique that Howard was talking about (although I haven't seen the discussion on Yahoo groups yet). IMHO, it has more benefit for scanning MF material than LF. It's the only way I've found to create an acceptably flat scan of roll film given the natural curl of the film and the poor excuse for a MF film holder which Epson provides with this scanner. I found it very difficult (or sometimes impossible) to work the bubbles from the edges of LF material. The heavy weight of the film base and the presence of processing clip deformations at the film edges makes LF tough to work with in some situations.

As to the scanner itself... The Epson 1680 is impressive given it's cost, (Chris - it's not a $350 model - it's more like a $1000ish machine) however it's not in the same league as a high-end CCD or drum scanner. If your transparency doesn't push beyond the Dmax-Dmin range of the scanner, the Epson 1680 can do a credible job. However, it doesn't matter what tricks you try with mounting fluids or the like, if the transparency has a broad range, you can't make any scanner see more than it's capable of doing. With that said, the coming years may be a challenge for the high-end CCD (e.g. Imacon) scanners. The Epson 1680 is an example of a fairly well implemented (except the film holders) lower-end scanner which is closing the image quality gap between low-end and high-end devices much faster than the high-end is extending their capabilities. One last note on the 1680 - don't waste your money on the Firewire version; it doesn't seem to make scanning any faster.

-- Larry Huppert (lnh62@removehotmail.com), July 20, 2001.


I'd be interested in knowing how a mounting fluid could be used with a scanner like the 1680. I just don't see how this is possible. First, the film holders do not allow the film to touch the glass surface. Secondly, the film/transparency mode does not focus at the glass, but above the glass at the film surface. I totally disagree with the statement regarding the film holders. Used properly, the holders will keep the film as flat as any enlarger glass-less negative carrier. As to deformations from film clips, why do you need film clips for sheet film? I have never had a 4x5 negative curl or deform when hang-drying. Never.

-- Matt O. (mojo@moscow.com), July 20, 2001.


Matt,

The 1680 has two focus points - 0 mm above the flatbed and 2.5mm above the flatbed. You can choose either focus point from within SilverFast on their vertical icon-based toolbar.

The film clip deformations are from the holders used in a dip and dunk processor by commercial photo labs to process E6. Unless you do your own E6 in a Jobo type machine, you end up with these clip marks.

I'd guess one of the advantages of using a mounting oil is it's the best way to keep the film absolutely flat when scanning and not have newton rings. The 1680 4x5 holder is OK, but it's still flimsy plastic and it doesn't really grip the film tight around the edges. Given that 4x5 film is pretty rigid and flat on it's own, the end result is OK. I've seen much better holders on other scanners (e.g. Imacon and the Umax rubber/metal holders). The Epson holder that I really dislike is the roll film holder. It's hard to believe that the film flatness when using their roll film holder is the same as you'd get out of a good enlarger. Epson designed a generic 6x17 holder which they expect you to use for 6x4.5, 6x6, 6x7, 6x8, 6x9, 6x12 and 6x17. It certainly reduced the number of holders Epson had to provide, but the one they did provide is all but useless IMHO.

-- Larry Huppert (lnh62@removehotmail.com), July 20, 2001.


There are some points to watch for when choosing a scanner. D-Max is one, true optical resolution is another but hardware optic quality, which has often nothing to do with resolution itself, is the key to crisp scans. Some (relative) low cost scanners have a high bit sampling, upto 48 bits and I would say they produce astonishing color accuracy. Their D-Max upto 3.7 and the possibility to adjust the gamma for dense images allows for very nice scans, at least on the computer screen. The scanner I have used in a 3K price range is the Quato X-Finity 48 (PFU). This scanner is very productive, uses SilverFast and has ICC calibration. You get a good scan from a good image. At least that is what an untrained eye believes. But when you compare with a high-end flatbed such as an Eversmart, a scanner that produces drum scan quality, you soon realize where some of the differences that (partly) justifies the much higher price tag lay. First, an antiblooming CCD for contrasty and noisefree scans, second an excellent sharp optic for crisp details right into the film grain, third a D-Max of 4.1 for detailed shadows and fourth an engine that privilegiates quality over speed.

Now you take the two scans and put them side by side. On the screen, at small size, all you can see is that the high end image is a little more brilliant and has richer tonal values in the shadows. Then you enlarge them and the sharpness difference appears. Even if the scan resolution was the same, one looks like a large format image when the other seem to come from a small or medium format scan in comparison. At this point, you try to apply unsharp masking to the low end scan to match the high end scan, but noise appears. Lots of clear pixels in the shadows.

So, yes, a low end flatbed can be as good as a drum scan for presenting an image on the web or even for a small print. And a high end flatbed (Fuji Lanovia, Eversmart Supreme) can be as good as the best drum scanner for a high resolution scan. And hardware is just one aspect of the final scan quality. Much depends of the skills of the operator too! I understand, Aaron, that you want to scan original B&W prints for offset reproduction? Then a good flatbed will probably do the best, there is no need to go for a very high quality scanner, as prints have not the depth of a negative or slide anyway. RGB, CMYK, this depends on the process used for the print. See your printer for details. If it's to print on an inkjet printer, an RGB scan will probably be a good start. Some inkjet printers make much nicer B&W prints from RGB colors than from black ink only, and otherwise, you can always convert the RGB scan into gray in Photoshop. Get as much resolution as you can for the price, but a minimum of 350 dpi at 1:1. It seems that beyond 700 dpi the difference won't be too noticable on most printers. For offset, a factor quality of 200% of the print screen is plenty (for example 350 dpi for the highest quality raster of 175 lpi ) A last word on unsharp masking: If the scan is for multiple uses and sizes, ask a for an unsharpened scan and apply the filter in Photoshop when the size of the output has been defined. Using a pixel ray of 0.3 and a theshold of 0 with an ammount of 200 to 500 works well for most scans.

-- Paul Schilliger (pschilliger@smile.ch), July 21, 2001.


This whole discussion does not make sense. I have an HP Photosmart that I modified to accept 4x5 negatives and transparencies. (Not hard) The film transports easily into the machine and the scans are incredible. They are as good as any drum scan I have ever seen.

The hype over drum scanning was invented by the manufacturers to separate you and your money!

I would put one of my Photosmart scans up angainst any drum scan, any day, for any amount of money!

Adam.

-- Adam Schillinger (adam6@aol.com), July 21, 2001.


I would like to thank all for their kind response. I'm absorbing the very useful information although I need to look up the meaning of some terms used here. Appreciation also to Paul Schilliger for his detailed and most direct answers to my questions. You've all been very helpful.

Aaron

-- Aaron Ng (ngaaron@singnet.com.sg), July 21, 2001.


You are welcome!

-- Paul Schilliger (pschilliger@smile.ch), July 21, 2001.


I would be interested in knowing how Adam modified the HP Photosmart to accept 4x5 tranies.

Thanks

-- Steve Seitz (slseitz@bellatlantic.net), July 24, 2001.


Yeah, I'd like to know how a Photosmart can be converted to scan 4x5 as well. I heard of folks slicing up their film into strips, but that's out of the question for me.

-- Guy (guy@spyra.com), July 25, 2001.

I'ld like to know if the Epson 1680 can be succesfully used for scanning 6x17 color and b/w transparencies, color negs and b/w negs?

Anyone done that successfully? I wan tot make pritn son my Epson 3000, size: about 44 inches maximum length, and about 17 inches max height.

THANKS

-- Adri de Groot (adrijanus@juno.com), August 20, 2001.


I would be interested in knowing how Adam modified the HP Photosmart to accept 4x5 tranies. ---------------------------------------------------------------------- Yeah, I'd like to know how a Photosmart can be converted to scan 4x5 as well. I heard of folks slicing up their film into strips, but that's out of the question for me.

Me, too. I have a Microtek Scanmaker 4 that I use for anything bigger than 35mm, but I've got an old Photosmart that still gives better 35mm scans than the flatbed (duh). Using it for bigger films sounds like a great idea.

Tony

-- Anthony J. Kohler (arbitrator@uneedspeed.net), August 20, 2001.


Sorry Adam, I don't think you've seen the results of really good drum scans.

Consider the specs: HP Photosmart has 2400dpi optical resolution. DMax (maximum density) is unspecified.

Drum scanners typically start at 4000dpi - and up to 25,000 for a serious one. DMax is up to 4.2.

The photomultiplier tubes used in drum scanners simply have a much wider dynamic range than the very best CCDs. This does make a difference that will be visible in many instances.

That said, for the original questioner's purpose, the difference wouldn't be that great. But the 2400dpi resolution of the HP limits enlargements to about 8X with a resolution of 300dpi so a 35mm image would be roughly the size of a letter.

I'd be the first to agree a drum scan is overkill for many applications, but to say it can be matched by any CCD scanner is simply technically incorrect. Apart from the machines' capabilities, an experienced professional drum scanner operator will be able to get better results out of any scanner than the most conscientious part-timer.

And I'm surprised to hear these are hard to find in Singapore, given the volume of high quality printing done there.

As for the price of drum scanners - it's simply driven by volume.

There's no way I'd suggest everyone goes for a drum scanner, or that their quality is necessary for every application. But for critical print reproduction work or significant enlargements, they're still essential.

I don't know what it's like elsewhere, but here in Sydney drum scans are cheaper than ever. If you're doing a few with reasonable deadlines you can get scans done for A$20-30 (US$10-15) each. Very reasonable when you consider you're getting a professional operator and a machine worth A$100,000+.

Hope this is useful. (Incidentally, I'm not in the scanning business, but have been buying high quality printing for many years).

-- David Glover (david@glover.com.au), September 12, 2001.



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