What is the difference between flatbed scanners and drum scanners. I shoot 4x5 mostly.Is there a noticable difference?
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What is the difference between flatbed scanners and drum scanners. I shoot 4x5 mostly.Is there a noticable difference?
There are many differences. Flatbeds use ccd arrays. Drum scanners use PMT sensors that go inside and acrylic drum. In flatbeds the sensor moves. With drum scanners the acrylic cylindar spins, with the film wet-mounted on the outside, and the sensor on the inside. Drum scanner tend to scan much better in the dense negative areas, they have lower noise, they kept the film perfectly flat, usually have higher resolution, have variable apertures that deal with grain better, and drum scanners can be setup to maximize the capture of useful information, whereas consumer flatbeds tend to record a bunch of non-useful information with their scans, i.e. a drum scanner can usually capture an image such that it's histogram is well populated throughout the range, but a consumer flatbed (even if 16bit per channel) tends to have the image information clumped in a smaller area of the histogram. Drum scanners, though, are fairly big, expensive, require more upkeep, and are less intuitive to operate. There are professional flatbeds that bridge the gap between consumer flatbeds/film scanners and drum scanners, but they often are just as big and expensive as the smaller drum scanners.
In my experience the best of the professional perform as well as drums and better than some. The skill of the person doing the scan is what counts.Quote:
Originally Posted by Peter J. De Smidt
They are as big as most drums and definitely as expensive.
Ted,Quote:
Originally Posted by Ted Harris
Have you actually done a scan on an Aztek Premier, or an ICG 380?
Those are the only two drum scanners capable of 3 micron aperture, and that have the concomitant workings to handle the higher optical resolutions, such as the real 7300 of the Premier?
Lenny
They work in two completely different ways. Flatbed scanners use an array of sensors (CCDs or CMOS) to scan the film a line at a time. The film lies flat on the flat scanner glass and the entire film is lighted at once. Because it's scanning a line at a time, flatbed scanners tend to be quicker than drum scanners.Quote:
Originally Posted by ignatiusjk
Drum scanners use three or four PMT sensors. The film is scanned one pixel at a time. The film is held curved against the surface of a drum and is rotated past a point light source. Because the light source is a "point" and the film is held in exactly the plane of sharp focus, drum scanners tend to be sharper than flatbeds. PMTs have greater dynamic range and very low noise; drum scanners tend to have higher Dmax capability than flatbed scanners.
All that said, several firms are actively developing flatbed scanners, and flatbed scanners get better with every new generation. While there are still three companies in the world making drum scanners AFAIK, none of them seem to have active product development efforts. So it's only a matter of time before the scan quality of flatbed scanners meets and then exceeds that of drum scanners. Assuming this happens before the often predicted demise of film of course. ;)
"Is there a noticeable difference?" It largely depends on how much enlargement you are talking about and how you are going to print. In general I can see the difference that drum scanner fluid mounting makes in enlargements starting around 3-4x, and the better sharpness in the 6-8x and higher range. Depending on your film and processing, your image, and how you print it your results will vary of course. It's pretty subjective.
So if your enlargements are fairly small, a consumer flatbed might work well for you. For middle range enlargements, the higher quality of a professional flatbed might work well. For the really big enlargements a drum scan might be called for. The only way to know is to get some film scanned in different ways, make some prints, and compare the prints. (Not monitor output, prints, that's important.) In the end, "you pays your money and makes your choice" of course.
Full (-ish) disclosure: I own my own drum scanner and drum scan my own 5x4 B&W and color negatives. So of course I'm biased toward drum scanners, else why would I have one? Just so you'll know ;)
a 4x5 printing upto about 15-20" wide, there will most likely be very little difference. Larger than that, yes the drum scan will out run the flat bed, sharper images, better grain, and possibly better tones. But tones are defined in your digital processing as well, since most scans are scanned with very flat contrast. At least from what I have seen. I've only had one negative drum scanned, as a test, and after the test I chose to stick with my home flat bed scanning (epson 4990) since I never print much more than 14" wide.
Daniel, This discussion is getting confusing because some are referring to professional flatbeds (IQSmart, Scitex Eversmart etc.) and some are referring to consumer flatbeds (Epson 750, Microtek M1, etc. The original poster did not specify and it has been confused ever since. Which are you referring to?
I'm referring to my Epson 4990, which from what I understand is probably close to the top of the consumer models. And admitably I've only done one test, but it was conclusive enough for me. The original poster didn't specify print size either, so I mentioned the general size I was referring to. I'm not sure how many people actually print very large though.
FWIW,
I'm still not sure what the original poster was referring to in terms of which quality of flatbeds to compare.
If we are comparing consumer flatbeds and good drum scans, I think there are obvious differences even in small size prints, but certainly dramatically differences at 16x20 from a 4x5 (which is why I have gone back to proflatbed or drum scans for all my exhibition work).
Comparing the professional flatbeds of Teds (Screen Cezanne and IQSmart) and scans from local pros who use either an
ICG 360 or a Screen drum scanner (assuming competent operators? These are all professionals who provide scans for the prints of world class artists), I frankly see no discernible difference in quality at the sizes I print (never larger than (20x24) of these pro scans, but prefer the work of Ted, because he is so client oriented.