I've recently been given some slides to scan, pictures from when Dana was a kid. After trying out the transparency adapter on my trusty Epson Perfection 1650, I realized that for these particular images I wanted more quality than the Epson could provide. It's an excellent scanner, but the slide/film part is a weakness.

So I purchased a Nikon Coolscan IV film scanner at the ol' flea market. The description was terse, simply saying that it was in good condition. Due the brief text and poor title wording, I gather that not many people saw this particular auction, because no one else bid and I got a smokin deal on the thing.

I waited patiently for FedEx to deliver, and I was happy last night when it appeared whole and intact. Even happier when it powered up and make little whirring sounds. But then my heart sank: I made my first scans, and they were abominable. Something was definitely wrong with the scanner. Fuzzy, faded colors, and a horrible halo-ish, glowy cast to everything.

I went to bed extremely frustrated.

In the morning, by the light of day, I noticed that interior adapter slot was literally covered in a thick, fine dust. Not knowing much about this type of scanner, I guessed that it had to have a lens and possibly a mirror at the least, and that it probably was just as dirty. Sure enough, a mirror directly under the adapter slot (in line with all the dust). A quick search found some great information on dirty film scanners, and how to clean them. The images I had scanned looked just like the examples I saw, and my hope grew. The excellent walkthrough I found was for a Coolscan 5000, but it was obviously very similar to mine, and it gave me the confidence to proceed.

It's easy to see why the mirror gets dusty, it's essentially an unshielded flat surface, especially if the scanner is left to stand vertically.

So I set out to clean my Coolscan IV. What follows is a brief HOWTO illustrating the cleaning process. Please look at the above walkthrough too, it's very applicable.

It should go without saying that if you follow this guide, you do so at your own risk. The process is not hard, but does require some coordination and patience. I assume no responsibility for your poor judgement, your small tool prowess, or your scanner's future productive lifespan.

First, remove the screws around the outer edge of the rear face.

Next, carefully slide the halves of the cover off.

To get the front faceplate off, use a flat screwdriver to gently pry the tab away from the chassis:

Here's the naked scanner:

Next, remove this front plate by removing its three screws:

Looking in from the side, you can see the mirror housing. The mirror is held in by a thin metal bracket:

You can see the two tabs at the top. These are what you need to gently pull away, so that you can drop the bracket and mirror down and out of the holder.

Looking from below, you can see the back side of the mirror being supported by the bracket.

Be extremely careful as you remove the mirror. I'm sure it will scratch or even break very easily.

Once you move the mirror assembly down, you can bring it out to the side of the scanner.

[Update 12/2008] One reader, Skinnyvoice in London, suggests inverting the scanner before removing the mirror bracket, so that the mirror does not fall out when removing the bracket. Thanks!

Here's the mirror and bracket. Look at all that dust!

I cleaned mine with lens cleaner and soft lint-free cloths. Be very careful, you really don't want to scratch this baby.

Installation:

When installing the mirror, you could try to balance it on the bracket and put it back the same way it came out. I found this to be difficult with my big fingers, so I inverted the scanner itself. This allowed me to drop the mirror into the holder, and then install the bracket 'over' it. Turn the scanner back upside-right and I was in business.

Here is the inverted scanner, with the mirror installed and the bracket going on:

After putting it all back together, I was thrilled to find that my problems were cured. The scanner had no problems focusing, and the images were crystal clear.

Before - This is roughly a 1/5-frame detail of the first slide I scanned:

After - (Note the photograph itself is not in great focus, but you can see the clarity in the dust and scratches on the slide):

From now on, I will use this scanner on its side, and store it covered, to minimize the dust problem.