Best approach to sand in lens assembly

Well, that worked. Fiddly though, at least three hours...

"Alex Bird" wrote in news: snipped-for-privacy@z14g2000cwz.googlegroups.com:

Sand = write off

(always)

I have repaired digital cameras with the problem. If you've ever taken one of these apart you'd understand how they're so sensitive to sand getting in the works. The retrofocus converter moves in these very complicated tracks as does the focus module. Sand can easily get into the interior of the lens through seams at the front and side of the lens. I worked at a pro camera rental place and I could tell you exactly where any lens had been after stripping it down and finding fine grit, beach sand, salt corrosion etc. Richard

Sorry Steve, but my crunch-free smoothly functioning camera must be the exception...

Alex

You're not joking. I was quite surprised by the amount of grit and sand inside, it certainly wasn't all from it's most recent outing.

A bit of a shock when I first tested it - no picture - panic. I hadn't plugged the ccd ribbon back in. What surprised me was that the camera functioned normally in every other way, no error message or anything, it's easy to forget the ccd is just another analogue sensor.

Alex

Alex, I bought one camera on eBay and after taking it apart and repairing it I asked the guy that I bought it from if he lived near the ocean since a lot of the parts had this characteristic oxide on them. He said not really but the Pacific was about 7 blocks down the street! Yah it's easy to forget one of those little plug in flex cables. It is funny that the camera operated normally, you'd expect it to at least generate a "focus error". I use a lot of toothpicks, tweezers and very fine needle nose pliers working on these things. Another tip is to make copious notes when you're going in and keep the screws in order using an ice cube tray. Nice and white and you can mark on it with fine markers the location of the screws you take out. Richard

Hi...

Making notes is good; but don't forget our hobby :)

Take lots and lots of pictures as you disassemble it, they'll be worth their weight in gold as you re-assemble.

Take care.

Ken

the

mark

Ah, I usually make some l> Take lots and lots of pictures as you disassemble it, they'll

I used another digital camera to photograph small gears etc before I pulled them out. It was actually quite a nice design and I didn't need to refer to the photos. Gears of alternating colours for example. I didn't relish unsoldering the ribbons on the lens, to get it apart, but it was actually quite straightforward.

Alex

I recently worked on a Toshiba laptop and it was quite nice. There were letter-number codes next to each screw so you could never get them mixed up. That fun-tak idea sounds great. I use the ice cube trays because it's like what we used to do at Helix. It also allows you to make notes on the trays and dedicate a tray to a particular camera since it might sit there for weeks waiting on parts.( now I'm thinking that I could use those dry wipe markers). This is quite helpful since there are many places where there are similar screws but of slightly different lengths and putting the wrong screw in the wrong place would result in a cracked or shorted something.

Yes Ken, I do that particularly where say like a lens needs to be reassembled in a particular way or as above a tiny gear train.

Wow that was a Canon? I've also had to do that a lot on Kodaks and really don't like working on them. Sonys, Fujis and Olympus have been much more logical to work on.

Richard

Correct, Sand is easy to clean out of a lens. Try getting advanced fungal growth off a lens without completely destroying the coatings, now that's hard.

Is the sand in the optics or just the zoom/ focus ring assembly? It' just requires a very careful, methodical disassembly and cleaning. The safest cleaning solvent to use would be denatured alchohol as most of the gears will be nylon plastic.(You'll most liekly need to strip off the old lube as the sand will be in it and won't come out completely untill all the gears and surfaces are clean and dry.) Compressed air is good as well, try and avoid using the dust-off stuff as it has a dry propellant that leaves a residue. You'll need a good grade of lithium grease to relube the gears and lens barrel, a thin grade of silicone grease will work as well. Use of a stiff nylon brush during cleaning is good as well, like a tooth brush or perhaps acid brushes which can be gotten at your local hardware store.(If you want to spend the bucks a local art store will have a variety of nylon in small sizes and stiffnesses.) Take photos or video tape the disassembly in detail to aid in reassembly and work in a clean breeze free work space to avoid dust contamination.

I actually used something that calls itself ceramic grease, which I'm pretty sure is the same stuff cd mechs and so on are greased with. It's white and light. Whenever I order some promising looking lithium or silicone grease it turns out not to be what I was expecting at all.

I actually used a sable brush, which I normally use for shifting dust, it's very soft.

This talk of brushes has reminded me of a brush I had years ago, but lost, never seen one since. It was like a toothbrush, a little bigger, with quite fine and stiff nylon bristles. It was fantastic for cleaning out fine threads. Where can I get another ?

Alex

Well the sable is good for brushing off the lens surfaces, that's what I've always used.( been a professional photographer for well over 40 years now.)

Sounds like a brush my old man had as well, he was an electrical engineer and used his for cleaning off armatures and relay contacts when washing them down with contact cleaner or whatever. You should be able to get one at a better stocked hardware store or an industrial hardware shop. Think I've seen them at industrial electrical supply shops as well.