Nikon DP-20 finder for the F4

Recently, as part of a beautiful, practically unused, late model Nikon F4s which (ahem) came my way, I immediately noticed a problem with the DP-20 finder. There was quite a heavy infestation of fungus on at least one of the internal eyepiece surfaces which was so bad it made viewing the lower meter readout difficult, blurring the LCD. I’d already knocked the seller down quite a bit (without knowing about this issue, of course) and so my initial reaction was not to demand a refund. I’ve fixed this kind of thing before – in lenses and more simple finder pieces – so how difficult would it be to eliminate the fungus from this otherwise pristine DP-20 and restore it to minty condition?

Well, as it turns out, quite difficult. But feasible, given care and patience.

This project required some careful planning, given the condition and obvious complexity of the finder. I got hold of the service manual for this finder which, unfortunately, is an x-generation photocopy scanned by an ancient scanner (probably) and so the image quality gives rise to a fair amount of guesswork. I was so determined to get this right that I bought a well-used finder for a cheap price, so that I could practice and note any caveats before working on the “real thing”. At worst, I’d spam it up completely and learn something in the process; at best I’d have a working spare finder that I could use for parts if need be. The practice run went very well in the end; a very grubby, fungus-infested DP-20 (though not nearly as badly affected as the minty one) with decomposing foam seals is now very clean, fungus-free, re-sealed and functioning perfectly, with just a few external scratch marks. I’m keeping it as a spare.

Now much more confident that I could do this, I set to work on the minty one. I’ll describe the steps I took in case this is of use to anyone else who wants to have a go at restoring their own finder. Note that this doesn’t require a complete disassembly but it’s worth mentioning that the finder optics and areas around are quite complex and fragile. With care there should be no need to de-solder any wires, but some patience is required.

The finder optics comprise three separate lenses in front of the prism (not including the screw-in eyepiece on the outside of the casing). The first lens is held in place by two small screws, whereas the second, which is able to travel forwards and backwards, is held in only at the top by the dioptre adjustment mechanism. The third and final lens, before we reach the viewing edge of the prism, is attached to the meter cell unit and is the most difficult to work on. The worst possible area for an infestation of fungus, if we were to try to remove it, would be the back-side of the third lens. Guess where it was in my finder.

Step one, a challenge in itself, is to remove the centre parts of the dioptre dial and meter selector dial without causing too much damage. These plastic discs cover the screws that need to be removed in order to remove the dials. They are held in with glue and are, frankly, a pig to remove because it’s likely that there will be some degree of marking to the outer parts of the dials during removal. To minimise this I covered the outer dials with insulation tape and then gently levered the covers out using a very small screwdriver. Once the screws are exposed both dials can be removed. Take care with the two washers for the meter selector dial: the white plastic one goes against the inside of the dial and the black foam one goes against the case.

After removing the four black screws of the outer case, the top can be lifted away from the body. A little bit of wiggling may be required here. The wires attaching the flash shoe to the main body are quite long and I didn’t need to detach them at all. With the main cover off the first lens can be seen directly, with the two screws holding it in place. 

Take the first lens off and inspect both surfaces; with luck any fungus will be here (this is where it was, mostly, in the “scruffy” finder with a tiny bit also on the front surface of the second lens). If there’s some on the back surface of the second lens then this can be taken out by first loosening the dioptre adjustment unit which sits on top. Notice the two small screws holding this part down (not the larger one; that can stay in place) and loosen them a a bit. Be careful here as the two mercury switches are held by this unit and they are glued to the unit underneath, yet there’s some play to take advantage of. The top adjustment unit may be lifted just enough to wiggle out the second lens, which is held there by the pin of the swinging arm. Again, inspect both surfaces.

If there’s fungus on the front surface of the third lens, it can be treated in-situ. If it’s on the back side, though, then the meter cell housing needs to be taken out. There are two screws holding this in place – a small one and a larger one, but this unit is the most difficult to get out so take extra care here. Remove both screws. Facing the lens, first lift the left side and then lift the right side a little. It may not appear to want to move much but persevere here, gently lifting either side and twisting slightly, firstly at the top, outwards, and then push up, swinging out at the base. Watch for wires snagging and gently lift them out of the way so that the lens/cell unit can swing outwards. Don’t pull it too far out. To clean the back side of this lens it will be best to turn the whole lot upside-down and move the unit out far enough to get at the surface, but no more. 

DP-20 insides
Lens no. 3 of the eyepiece group – clean and clear. Nearly half of the inside surface was covered in fungus.
DP-20 eyepiece lens group holder- side view
Side view. Notice one of the mercury switches and wires going into one of the meter cells in the lower left of the picture.

Once clean, re-assemble everything in reverse and look for any wires that may have become detached. I had just one such casualty – the black wire of one of the mercury switches – which was a simple fix with a soldering iron.

Neither the fungus in scruffy nor that in minty had etched the glass coatings at all and so I was able to remove it completely, using my usual method. There’s no secret to this, although people tend to have their preferences as to which tools and compounds to use. I have cleaned fungus from photographic optics for a few years and I’ve never had any return, using simple, easily obtainable isopropanol, cotton buds, cocktail sticks and certain brands of optical cleaning wipes which are, specifically, impregnated with alcohol. It’s the cocktail stick wrapped in an optical wipe which really does the trick, with gentle rubbing over the affected area. If necessary, the area can be finished off with an optical-grade microfibre cloth. Perhaps stronger chemicals, such as hydrogen peroxide, may be required for very well-established fungus but I’ve yet to encounter any.

Pentax ME 

Not the ME Super, but perhaps the ME Better!

Pentax ME

I think I struck lucky with this one. Found, by chance, when searching for a Pentax-M 50mm lens, the description of this item detailed the lens only and was priced at about the same as the lens alone would go for. But all the pics showed the camera too, so I asked the seller to confirm what was included in the sale. The answer: everything! I snapped it up even though I wasn’t sure I’d need the lens (see previous post) because the camera looked so clean. No knowing whether or not it would work, though, so it was another cheap punt.

This is the camera that led to the later, and much more popular, ME Super. The latter has many refinements but, as I have discovered, also involved some cost and weight reduction by replacing some of the metals with plastics. One of the reasons I prefer the look of the plain ME is the metal top cover with the ASAHI stamp; the Super has a top cover which is mostly plastic but plated with a metallic outer and, as such, has a slightly different appearance. There are no buttons near the shutter dial on the ME because it’s not possible to set manual shutter speeds on this model; it’s aperture priority only apart from a purely mechanical speed of 1/100s (x-synch for flash) and B. The shutter dial itself is more robust on the ME, compared with the all-plastic affair of the Super, and I prefer it even though it results in a more fiddly process to remove the top cover. Most of the remaining differences between the ME and the Super are inside.

So, upon arrival, the lens seemed fine apart from the fact that it was very dusty inside. No fungus (unlike the one that had arrived just prior to this) and mechanics were fine. This was a simple, half-hour job to dis-assemble, separate the main groups either side of the aperture blades and blow out the vast majority of the dust that had settled onto the two surfaces there.

I noticed immediately that the camera’s wind-on lever was loose when near the end of its travel and it didn’t click closed. The shutter, though, seemed fine as did the electronics and meter display. I knew what this meant: the “click spring” had broken off inside. The purpose of this spring is to secure the wind-on lever close to the camera body to, firstly, switch off the meter and, secondly, prevent accidental partial wind-on. Easily overlooked but should not be; the broken-off bit of metal can travel down into the workings or even shutter and seriously jam or permanently break something. I decided to resist the temptation to check shutter speeds any further and see if I could fish out the broken spring. Luckily, after removing the camera base plate, a few short shakes resulted in the piece in this picture falling out.

Broken click spring
Broken-off click spring. Better out than in!

Safe now to carry on testing, I figured all seemed well apart from the usual need to replace the mirror buffer and light traps.

I ended up harvesting a click spring from a parts-only ME Super (the springs are identical) and installed it into the ME. The Super has a refinement, though, where a second, coiled spring is used to strengthen the main click spring and presumably make it less likely to break off. The coiled spring is held around a post and is sprung against a second post, neither of which are present in the ME. I discovered that both posts are direct replacements for plain screws in the ME and so I gave the ME the Super’s full click spring refinement job! Perfect.

With the top cover still off, all that was left was to remove and replace some crumbling old foam which was meant to cover the open area where the meter LEDs go, leading straight into the area between prism and top surface of the screen. This was a very fiddly job and resulted in more cruddy bits than I wanted to see when looking through the viewfinder, so when all was sealed again I removed the prism and cleaned the underside, the viewfinder side, the back of the viewfinder lens and the top surface of the screen. The prism itself is held in by two tiny screws – one on each side – and removal requires the electronic boards to be carefully lifted away from the top surfaces first of all. After loosening the two prism screws the entire prism will then lift out. It’s the same situation in the ME Super and it’s the only way to remove debris that has found its way into the space between prism and screen, since screens are not user-removable in these cameras. The eventual replacement for the ME Super – the Super A (Super Program in the U.S.A.) – does have user-changeable screens which, if nothing else, makes cleaning much easier.

I have renewed the mirror buffer now and will soon replace the light traps in and around the rear door so that I can run some film through. I love the mirror/shutter sound and feel of this camera; there’s something very reassuringly 1970s about it and that’s only meant in a good way. It’s ever so slightly less dampened in movement compared with the Super but it’s certainly no Spotmatic in terms of noise or vibration. And that’s not to say that the Spotmatics are bad, either – far from it.

Something worth mentioning is that I get the distinct impression that the ME suffers much less from the very common shutter and wind-on issues that many Supers will suffer from now, if not serviced. Perhaps because it’s slightly less refined internally, with fewer plastic parts. My Super had the wind-on issue (film winds but shutter won’t charge), which I appear to have fixed without the need for a full service, and my (much more shabby) parts body has the same issue which can’t be fixed in the same, relatively simple, way.

So, is the ME better than the ME Super? Purely in terms of functionality, not really, and yet I prefer it. If you’re on the lookout for a fully working ME Super and don’t care much about manual shutter speeds, give the ME a go.

Saving Pentax-M

I’ve just spent pretty much the entire day restoring a Pentax-M 50mm f/1.7.

img_0201
Fungus-free!
I not able to do much moving about at the moment and so, rather than mope around and feel sorry for myself all weekend, I thought I’d spend an hour or two doing this. Lesson number one: estimate the time required to clean and restore a lens as bad as this was and then multiply it by three.

The lens arrived this morning from a well-known auction site and my expectations were fairly low from the start; it was at a buy-now price which was about half that of most others, with no real description to speak of and no way to see close detail from pictures. This was a cheap gamble and I was expecting to do some work on it, but I wasn’t quite prepared for the state of the thing when I examined it. Not that it needed close examination to see that it was completely infested with fungus – the worst I’d ever seen.

The outside barrel wasn’t too bad; a little grubby but easily cleaned. The elements, though, looked completely stuffed. Just about every glass surface inside and out was covered in masses of threads and patches of mould. Nasty! I’ve had success at cleaning fungus from elements before but I have to say I was close to giving up on this as it was so badly affected throughout. Pretty much unusable, optically.

OK, so it may take more than an hour, I thought. More than two, even. All in all, it took about six hours! Was it worth all that time, considering price difference between this one and a good one? Well, yes and no but I favour the “yes” because it gave me a project to do whilst unable to go out and, more importantly, I have saved a now-decent lens from the scrapheap. Make do and mend!

Often, it’s said that fungal infestation of lens elements is the end for them: the fungus etches into the coatings and, sometimes, the glass itself, causing irreparable damage. Up to now, though, I’ve been lucky as I’ve been able eliminate fungus on a few old lenses without leaving much permanent damage, if any at all. This lens turned out to be no exception but it’s been the most laborious lens-fix I’ve ever done, without any mechanical fixes, even, as everything mechanical worked perfectly. It was necessary to separate all of the individual elements and clean all surfaces which is very, very difficult to do because, even with fungus all gone, getting truly crystal-clear cleaning results on internal surfaces, without any smears whatsoever, takes a lot of time and patience. Still, time is what I’ve had and it did pay off in the end. Lesson number two: do not use a blower bulb with a metal end too close to an internal surface because one small slip could result in a permanent coating mark. Doh! Thankfully tiny and won’t affect anything but still, a swear-inducing moment.

I wish I’d taken a “before” picture but I honesly didn’t think I could salvage it so didn’t bother. Believe me, it was horrendous! Here it is again, in its fully restored state (I restored the filter, too, which was also in a very sorry, mouldy state but it’s a nice Hoya one so worth saving. I had to take the glass out of the frame to clean everything but all’s well and clear with that now, too):

img_0202-1

When elements and groups are taken apart and re-assembled it’s always a good idea to check for any misplacement or decentring as a tiny amount of misplacement of any individual element can have profound optical consequences. I’m glad to say all is well, wide-open and at high magnification (digital test). I replaced the front name ring and cleaned the barrel exterior thoroughly.

One clean and clear lens to add to the collection, and a very good one at that. I could now sell it for twice the amount I paid but it’s definitely a keeper.