Scanners with large depth-of-field?

Question

How can I find a modern flatbed scanner with a reasonably large depth of field? Here "reasonably large" would be something like at least 2mm of DoF above the scanner glass.

Typically DoF is not listed anywhere in the technical specification, and few people are interested in testing it when they are reviewing a scanner.

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Based on what I have learned so far, it seems that older scanners often had a fairly deep DoF. For instance, my old (> 10 years) HP ScanJet 4200C performs reasonably well.

However, many modern scanners seem to have an extremely shallow DoF. My guess is that this is related to the fact that older scanners used a CCFL lamp while a modern scanner often uses LEDs. With LEDs, the scanner can be made much thinner. Perhaps the small physical size of the scanner favours a lens that has a shallow DoF?

But this is just a guess, as I don't really know anything about the construction of the "lens" that is used in scanners. Can one somehow explain it in "SLR terms"? Does it make sense to use terms like focal length and aperture in the context of a scanner?

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Some background: I am abusing my scanner as a digital camera; I use it to take pictures of nearly flat objects. For example, if you need a quick snapshot of a handmade greeting card (flat decorations glued to a cardboard background, etc.), a scanner is surprisingly convenient in comparison with a DSLR: you don't need to worry about aligning the camera perpendicular to the object or setting up lighting, and you won't have any lens distortion that you need to fix in post.

However, this is possible only if the scanner has enough depth of field above the glass.

Answer 1

Using a scanner as a camera is no abuse at all, Scanography is certainly photography and arguably an art form.

In order to achieve the necessary DoF, you will need a scanner with a CCD sensor. The newer (and thinner) ones use a CIS sensor and thus have a very shallow DoF. Just keep in mind that most CCD scanners are going to be more expensive.

You may want to check Robert Louis Fleming's blog, for a lot of interesting approaches to scanography and his quite beautiful results.

There's also a short tutorial for scanography on PhotoGalaxy

Answer 2

You are correct that older scanners are more likely to have a larger DoF, this is because many "old" scanners you can find secondhand are going to have CCD scanning technology which has been phased out in favor of cheaper (and in many use cases better) CIS. Nowadays, CCD technology is mainly found in higher-end "photo scanners" and large-format scanners which cost even more. The spec sheets from the manufacturer for any given scanner (just google "scanner model specs" or "scanner model manual") should say whether they have CCD or CIS, but you may not see DoF listed. If you find a database or source for scanner specs which is more comprehensive, I'm sure people would appreciate you posting it here.

Answer 3

When I started in graphic design back in the mid 90s, epson was my printer and scanner of choice. Outstanding results up to 13 x 19. Related to this series of Q&A, I purchased at considerable cost and epson 10000Xl scanner. 48 bit color depth and the ability to scan up flat and sometimes not very flat objects. It would capture up to .25 inches depth of field in focus with the next .25inches to out of focus blur. The effect of the scanners was that of a close up lens. It worked so well, that when I became leade graphic designer for a well known battery wholesaler located in Miami, I was asked to photograh blister cards with cells inside for use in printing and on the net.

I search eBay and located and bought a used (guaranteed to work) Epson 10000XL scanner. Next was to located software, network interface for distance location. The scanner is quite large and heavy. I did find a brand new net card that would be ready to use after installing in the scanner. The scanner software is still available from Epson. The compuer has to have Win 7 or older to run and drive the scanner. It worked so well and was faster as I could scan up to 12 cards at one time. Colors were always perfect.

Step forward another 4 years. I left the company and returned to my graphic and web design business. Used for a few special projects. Recntly the Battery company asked me to provide updated product images and even new product images. I dusted it off and it works just like it did 2-3 years ago.

You can not find anything new that I am aware of today.

Answer 4

I'm aware of at least one 3D scanner manufactured by HP called "Top Shot". It uses an array CCD instead of a linescan CCD + scanning mechanism, so it should also capture images faster, although the effective resolution is likely not quite as high as a traditional flat-bed scanner. The downside/upside (depending on your needs) is that the scanner is part of an all-in-one printer.

I've casually played with one and came away impressed, but I don't have any in-depth experience with the product.

Here's a link: http://www.hp.com/united-states/campaigns/topshot/index.html#.UIGFUG_A9QQ.

Answer 5

The Fujitsu SV600 overhead scanner has close to 2" DOF. BUT it is really unstable with scan head (where the weight is) about 18" above the base - about 4" x 8" (and weighing almost nothing). I have one in my office. One of our suppliers has made a base for it to make it much more stable, but it also makes it BIG. Footprint is about 24" x 30".

Answer 6

The Canoscan 5600F has a great depth of focus and is relatively inexpensive. I use it for scanning circuit boards populated with components.

Answer 7

There are scanners that are advertised as having 3D object scan ability. A search at Google came up with an example. I believe the DoF should be deep enough for your needs.

Answer 8

Scanners like Epson V370 come with a plastic attachment to scan film and slides in their frames. DoF should be at least 2mm to keep them in focus