Archive | January 2017

The Kodak/Pakon F235 Plus, revisited


Yeah, we still have it. Not the magic touch, but the scanner (with the magic touch). Potions of the below appeared on years ago; I have added some updates and new notes on light sources, a subject on which there is tremendous misinformation on  the ‘net.

What is a Pakon? 

The company is best known for its plastic slide mounts, which in the old days you would buy to fix the cardboard mount that your projector mangled. But as division of Kodak, it began to produce minilab scanners (the F135, F135 Plus, F235, F235 Plus, and F335).

Many people are familiar with the Pakon F135 and F135 Plus, which have become very popular as tabletop scanners. What makes these scanners genius is that they do scanning on one pass, without annoying prescans or the rat-a-tat-tat of stepper-motor driven film scanners.

The PSI software is even more ingenious. Basically, you feed it a roll of film, and:

  • It can take strips of film up to and including a 40-frame uncut roll.
  • It scans all of the frames as a bitstream image at rates in the hundreds of frames per hour, with Digital ICE turned on.
  • It uses DX codes on the film to determine the frame number and applies that to the filenames of the resulting files (JPG, TIFF, or RAW, to your preference)
  • It automatically finds the frames, DX coding or not. On its software, you can adjust framing after the fact.
  • It quickly and with astonishing accuracy corrects color and exposure, even on frames with exposure errors or fading.
  • It spits out all of the files, in sizes up to 3000×2000 (this is a 2000dpi scanner) onto your output drive or media (some earlier models require software fixes to output at this resolution).
  • It does not require a special console, just XP (real or emulated) with an unformatted N partition on the boot drive. You install the software and go to town.

If you are feeling especially technical, you can use the TLXclient software, which allows different bit depths, full-out-to-the-edges framing, unusual frame sizes (you can scan individual half frames or Xpan frames – or output them as full-resolution strips), and many other things. It comes into play more, one would surmise, if the Pakon is your only scanning machine.

How is a Pakon different from other negative scanners? 

This minilab scanner differs from your Coolscan in a few key ways.

First, they are designed for speed.  An F235 Plus, for example, will do 800 frames an hour at 3000×2000 resolution. Yes, that’s 33 rolls per hour, or a roll or 24 frames about every two minutes. Most people would burn through a lifetime of black and white 35mm negatives in a few days of work. The 135 series runs at about half that speed with ICE off.

With Digital ICE turned on, the 235 Plus still does 400 frames an hour.  Reduce the resolution to one of the lower settings (such as what you would use for web-sized pictures or 4×6 prints), and it really flies.  Part of the speed comes from obviating negative carriers, the cumbersome and relatively fragile part of any consumer-grade scanner. The rest is dispensing with the prescan, which introduces more complication in the process.

These are the relative speeds of Pakons vs each other (Digital ICE off / Digital ICE on) for a maximum-resolution scan. This is per hour. Loading film in strips slows this down slightly. This is the order in which the machines were released:

  1. F235 (400 / 250)
  2. F235 plus (800 / 400 )
  3. F135 (293 / 220 @ 1500 x 2000)
  4. F335 (1053 / 790)
  5. F135 plus (477 / 387)

One thing that is clear is that the speed of Digital ICE processing ramped up to where it was very close to the limit of the scanning speed. But that is of no moment if your life is all silver b/w or Kodachrome, where dust and scratch removal doesn’t work.

Second, Pakon scanners are designed for a minimum of human intervention.  Despite the availability of an SDK for this scanner, the proprietary PSI software is the only fully finished piece that will run this scanner. This software, by the way, is brilliant in its simplicity.  Even in “advanced” mode, it has only a few settings: what type of film (color, b/w, slide), how many frames per strip (4, 5, 6 or many), whether you want Digital ICE on or off (color only), and the roll number that will become the name of the folder when you save the roll.  That’s it.  The machine scans as much film as you want to give it, figures out where the frames are, does all color corrections without human intervention (unless you want to participate) and kicks out your choice of output (3 resolutions, JPG or TIFF, RAW or processed).  It even reads the DX codes off of the film and gives each frame the name of the nearest barcoded frame number.  Brilliant.

Buried in your program folder is something called TLXclient, which you can use for oddly-sized frames (such as half-frame 35mm and Xpan). It’s a little more geeky, but it lets you play with wide frames (a lot of the time you can get black all the way around a 24×36), play with the bit depth, and do other things that aren’t really central enough to PSI’s minilab mission.

Finally, the Pakons not generate information that you do not need.  The first thing that a gearhead will look at is the scanning resolution.  The maximum is 3000×2000 (6MP), which is an acceptable resolution for an 8×12 on a dye sublimation or inkjet printer, if not a Frontier.

“Wait? 4000dpi!” Most 35mm pictures don’t get enlarged more than 8×12, most in fact are just shown on computer screens these days, and for situations where you need to, you can always use a high-end desktop negative scanner, pay to play on Flextight, or have your work drum scanned.

If all you are out to do is quick proofs to see what is worth scanning with a much higher resolution machine – and just want 1500×1000 thumbnails, the F235 plus blows out up to 3,000 of those an hour, or roughly one per second. You would need a spotter to catch the negatives flying out of the machine. And a second helper feeding it.

But let’s be real here. If you for some reason believe that you need to scan every single picture you have, you will never get it done on a normal negative scanner that runs with a carrier and Vuescan or Silverfast.

What’s different about the F235 Plus?

The 135 and 135 Plus have a “dog bowl” form factor in which film travels in with the sprockets at top and bottom, around a curve, and out the other side. Negatives end up neatly in the tray. They are not as fast as the 235 and 335 series machines for a number of ergonomic reasons in addition to the slower transport speed.

The 235, 235 Plus, and 335 use a larger chassis (about the size of a large bread making machine) and take film straight through and out the back into a negative bin made of Lexan. The 235 Plus and the 335 are the speed demons, with the 335 — exceptionally hard to find in working order — edging out the 235 Plus by 20% with no ICE and almost 100% with ICE. They can take shorter strips of film than the 135 – down to two frames – though you may want to use a chopstick to nudge the strip to engage with the sprocket rollers.

But the real difference with the 235 Plus is that it uses a halogen light source and not an LED. Many people have made uninformed suggestions that this bulb is somehow difficult to find, expensive, or otherwise a problem. It’s not. You can access it by taking one magnetic-catch cover off the scanner.

The exotic-sounding “Solux” bulb is a actually a 12v, 50W EIKO MR16 (GU5.3) track light bulb whose only special parameters are that it has a 24 degree throw angle and has a 4700K calibration (so close to daylight). This bulb was not actually developed for the F235 series but was an off-the-shelf (and still current production) art museum track light bulb whose fitting, voltage, and wattage are identical to bulbs in lamps you probably have around your house. So even if you had to wait to buy a 4700k version for a whopping $10-14, you could march down to the local hardware store buy something reasonably close for $2 and be back in business in minutes. Witness:


Does this bulb look familiar?

So what? You ask. LEDs go 10,000 hours instead of 1,000. Why should we put up with a bulb that has to be replaced? One could always point out that 1,000 hours on this machine is 800,000 b/w negatives, which is several times more than anyone outside a professional photojournalist shoots in a lifetime.

But the real reason is color. A lot of early Kodak scanners ran on halogen light sources. Why oh why? It’s all about color. Kodak was always fixated on perfect color in all of its systems, and at the time that the F235 and F235 Plus came out, and even now, you can’t get a Color Rendering Index of 98 with LED. CRI is the measure of how even a spectrum a bulb produces compared to a reference light source, and until recently, LEDs have scored very low because they have holes in their spectral transmission. And if you are fixated on the quality of color through transparency film, the white LEDs that were in play in the Pakon era were nowhere near hitting the barely 90 CRI that LEDs are hitting today.

The other thing is that the F235 system is highly diffused, like a diffuser enlarger. LED light sources are very concentrated and often very unforgiving of other than perfect negatives. If you have ever compared the output from a Nikon LS and a Flextight (or a Sprintscan), you know that diffused light sources don’t multiply the retouching workload later.

So how did LEDs get into the 135 and 335? They were later machines, and as slide shooting went off a cliff, there was little call to maximize color rendition for that application (and even the declining use of film made the slower speed of the 135 completely livable). LED turned out to be fine for negatives (note that the 135 series did not have native chrome capability until a later version of the software, which might be employing its own methods to correct for the light source).

Today you could probably retrofit the 235 with a direct-fit LED bulb (query what might happen if you put the scanner in “dim” mode, though) or pretty any much light source. The machine calibrates itself to the light source on startup

But in general, the F235 Plus is a very fast platform that is easy to clean, does not twist your negatives around curves, and is more suitable to scanning several rolls, then correcting them all at once, then hitting the next set. The one downside is that it does have a fan, and so it is a little louder than a computer. Not 747 jet-engine loud, but still noticeable.

The only sad thing about the F235 Plus is that you might find that your life’s production of negatives zips right through, and after you scan all of the negatives in your family and from some of your friends, there are no more worlds left to scan, er, conquer.

I booted mine up after having it in the box for a while. I ran a few long rolls of film that I forgot about until after I moved. It’s magic. The machine is genius. But now what?