Inside the 18-70mm DX lens

[Dallas]

My 18-70mm DX has fungus on some internal elements, so I thought I would try and clean them myself. Taking the lens apart was kinda fun, but I don't recommend it to people who have a low patience level with intricate stuff.

This is what it looks like with the mount off:


The PC board is only held on by one screw and the chips buses detach from their terminals by means of little sliders that release their grip. Easy to take off, but not so easy to put back on!


The polycarbonate casing slides off once you remove the focus switch.


The rear element group has its own housing which attaches to the inside with three screws, revealing the middle group when they are removed:


The second rear group of elements are also held in by three screws. I tried in vain to get this group out, managed to remove two of the screws but the third one refused to budge and I think I have now stripped the head of the screw, so unless I figure out a way of removing it, looks like this lens group isn't ever coming out!


Unfortunately the fungus is on the underside of this group of elements as well as on the other side of the diaphragm. Looks Like I need to try and figure out a way of getting to the front elements as I can't seem to find a way in from the rear.

Anyway, putting the lens back together was more challenging than taking it apart, but I am pleased to report that it is all back in one piece and fully functioning (and I don't have any spare screws!).

[Nikkor]

It seems like you love challenges  so how about you give us a photo of the fungus

[Dallas]

Dude, I tried to! Unfortunately holding the lens up to the light, with a screwdriver wedged into the crevasse where the diaphragm lever needs to be held open AND holding the D2H with the other hand didn't result in very good pictures! Not to mention that I was pretty cheesed off at that last bloody screw not wanting to play ball. Those things were in there tight!

[Tom]

Very interesting, Dallas. Satisfies my curiosity.
But how did you get fungus in your lens?

[Dallas]

Extremely humid environment here. Since I got the 18-200mm I put this one in a cupboard and when I had another look the little spidery webs had started. At first they were quite small and seemingly limited to only one element, but on closer inspection today I see it is on at least three of the elements, but in sections of the lens I can't get to.

I seriously need to invest in one of those dry-box/de-humidifier things, but I wouldn't even know where to find one.

[davepaterson]

I seriously need to invest in one of those dry-box/de-humidifier things, but I wouldn't even know where to find one.

eBay. Everything in the world can be found on eBay. 

[Dallas]

True, but the majority of guys selling on eBay aren't in favour of dealing with us guys outside of the US or Europe. I can't imagine how much the shipping of those things would cost!

I wonder if it would be possible to convert one of those small bar fridges into a dry box? Replace the thing that makes it cold with a thing that makes it dry?

[Makten]

You could just put lenses that you don't use in an airtight box or can, and put a little bag of "silica gel" in there. You know those things that comes with every electronic device you buy. The silica stuff will take care of the moisture in the air of the can, and thus the lenses will keep dry. You can even try ordinary rice! It works the same way as the silica, but not as efficient of course.

The fridge idea isn't too bad. Actually, you could just put the lenses in the fridge as it is. Cold air can't contain as much water as warm air, and therefore the humidity is much lower in a fridge. The problem is when you take 'em out. Cold lenses in warm humid air isn't a good idea, so they would have to warm up inside a plastic bag or something before use.

[azkober]

Processed white rice makes an excellent cheap dessecant.  Womens nylons make an excellent cheap dessecant container. Put the rice and the lens(s) in a shoebox and voila!

[Blue Shirt]

Why don't you just drill out the third screw? You already have two others that you can take to the hardware store as samples to locate a replacement.

Since you have gone this far with disassembly, I dont think a few brass drillings would be too much to clear out on top of cleaning our the fungi.

[Dallas]

I did try that but wasn't getting anywhere (all I succeeded in doing was spreading more filings into the lens - and I broke the skinny little drill bit I was using when I knocked over the drill ). I think I should be able to free it with a pair of needle nose pliers. Will need to buy a pair. Anyway, the fungus is on the other side of that lens group, so I need to get in from the front of the lens somehow. There must be a way in...

[davepaterson]

To go back a few posts in this thread . . . to Dallas's photos of the opened-up lens (admire your bravery, Dallas). I'm no technophobe, but I find the picture of all that circuitry inside a LENS quite terrifying. All those components just waiting to go wrong . . . I'm so happy I still have a couple of those lovely old manual lenses from the days when Nikkors were so beautifully made, and the only moving part was the focussing ring. Well, ok, and the diaphragm selector.

All the electronics reminds me of cars (always a sore point) which are also full of electronics nowadays. Mine just cost me £280.00 (nearly $600US) because some chip in the "engine management system" went awol.

I love digital for all sorts of reasons, but I'm very glad I still have a couple of cameras (6x9, 6x17) which don't even need batteries.   

[nfoto]

The insider's trick for getting those pesky screws out:

1. Have a screw driver that fits the screw head perfectly. Whenever you try to turn the screw, press the screw driver hard down (very important), and wriggle ever so slightly back and forth while pressure is maintained. Never apply much torque sideways or the head will be damaged.

2. Pre-heat the screw head using the smallest soldering iron you can get hold of. Press the tip of the iron onto the screw head for 30-45 secs, wait 30 secs, then try to get the screw unstuck. If it won't yield, re-apply heat treatment a couple more times and then try again.

Trying to drill out the screw generally  is a bad idea. The screw is always harder then the material surrounding it, so you likely end up making a big mess out of the situation.

[Nikkor]

2. Pre-heat the screw head using the smallest soldering iron you can get hold of. Press the tip of the iron onto the screw head for 30-45 secs, wait 30 secs, then try to get the screw unstuck. If it won't yield, re-apply heat treatment a couple more times and then try again.

Excellent tip

[xavier]

A small watt lamp inside your cupboard will heat the air inside as small as 5 degrees Centigrade above environment, should be enough to help you get rid of humidity and mold. High wattage lamps will cook your lens and dry up the lubricant. I used that before I bought an electric dissecant box. On my area, there are warm electric tubes at about 40oC or more to put mold at bay which you can touch with your hands and not get burnt. These electric tubes are also used inside piano to keep it dry, inside.

[Seanna]

Dallas,

Now I know what the inside of my lens looks like, thanks for the tips should I need to try the operation myself at some point.
I save every silica pack I get and keep them in my camera bags too.  Also, a product called DampRid, if available there works well to soak of humidity.

I have an old Oly C-750 sitting unused in a drawer that I will be attempting an IR mod on during Christmas, haven't found a tut for that anywhere so this will be a fun attempt at electronic surgery ... (post a link if anyone runs across a tut site ... and no there isn't one on Lifepixel)

Bjørn,

Since heat causes most (all?) things to expand it would seem counter intuitive to apply heat to the screw to get it to loosen up.
Unless it is to eliminate the bond of a "screw glue" like Loctite.  Would that be the purpose of applying heat?  Or would the process of expanding and shrinking be enough to break the bond of  a stuck screw?  Does sound like a great tip and I'll give it a try next time I run into this problem.

Robin

[Makten]

A small watt lamp inside your cupboard will heat the air inside as small as 5 degrees Centigrade above environment, should be enough to help you get rid of humidity and mold.

If we're talking about humidity in the air, you will not get rid of it by increasing the temperature. Warm air can contain more water than cold air. The only thing that happens is that the relative humidity drops, but that doesn't change the absolute humidity.
You may get rid of the mold though! I don't think it likes too high temperatures.

[annedi]

Don't forget that silica gel desiccant needs to be periodically "baked" in order to
restore its drying properties.
Once one of those little containers has absorbed moisture it is basically useless
unless it can be dried out.
I bought some bakeable desiccants and humidity indicator cards from this guy --
no affiliation -- and he has a lot of good info on his pages.

http://www.jakesmp.com/CSD_Silica_Gel/CSD_Silica_001_M.html


**********
Dallas -- What if you put the lens in the freezer to contract things ?
(Hey, would that also kill the fungus ??)

Is that stuff fungus or mold

[Dallas]

Some interesting comments coming through here. Thanks everyone.

I think it's fungus, Andrea, but I wouldn't know if it is the same thing as mould. We get that a lot in this environment. I have some old lenses that I send off to my tech guy every couple of years for cleaning. I want to start doing this myself, hence the attempt at the 18-70mm. I figured that if I could do an advanced DX zoom any other lens would be a piece of cake.

I used to use silica gel in the past but I found it didn't help all that much. The rice in the salt is a common thing down here - I never thought to try it with my lenses though! These days I keep all my equipment out of dark cupboards and on the shelf in my office, with the lens caps off in the front. I am told that the fungus can't grow in light, so with them out in the open hopefully they will offer more resistance.

[Fanie]

Dallas you can remove the front element by taking the elastic rubber grip of, exposing a single screw. Once this is undone the front element with housing twists out of the assembly, exposing the other side of the middle optics group.

Getting the front housing alligned and back into postion is extremely difficult though and tests your perseverence 

I also had problems removing the same screw you have, and in the end just hacked the little plastic tab of with a steak knife, leaving the screw in place. The tab was superglued back in place during assembly. I was desperate to get it usable for the balance of our Mauritius trip, and knew it would be replaced by insurance 

Here is a pic when I had mine stripped to clean salt out of it after it dropped into the sea.