Dropped a camera today :(

[JohnR]

First time ever. I would like to claim it was while heroically hanging off a cliff face getting the shot of a lifetime, but in actual fact I was getting out of the car at home. Dangit! It was in a bag, and the filter gave its life to protect its master. Even so, the lens must have taken a bit of a whack as it now jams up in the middle of the focus range. Looking at it, it actually looks like the bit with the glass in it is binding on the bit that it moves through near the back of the lens... if you know what I mean. Here's a picture, it looks like a trick of the light but it's not, the gap on the right is bigger than the gap on the left.





This is a 100mm Series E lens (Nikon). I think I had this problem before with a 50mm E lens, so the first challenge is to get the three screws off, as two of them won't budge. Would a drop of WD-40 to loosen the threads be the best bet here?

[Mike Kovacs]

So it landed nose down on a protective filter?  Is there any sign of distortion to the filter ring in the front?

What I think has happened is the lens barrel is distorted.  There is no easy fix for this - it needs to be straightened, if indeed it even can be.

PS oil (esp WD-40) + lens = disaster.  Don't even think about it or I'll have to find ya down unda and kick'a yo a....

[JohnR]

LOL. What can I use to help get the screws out then? Don't tell me a bigger hammer

So it landed nose down on a protective filter?  Is there any sign of distortion to the filter ring in the front?

Nose down It can't have been much more than a foot... and a half? The filter ring looks fine. Maybe it's a goner, but I'd like to have a go at it anyway...

[melek]

Rule No. 1 of camera repair:

-- Never use WD-40 ... ever!

I think a number of us have tried it, and the result it always the same. A collossal mess that takes forever to remove.

Mike's assessment sounds about right. Given that it's not a hugely expensive lens, you could try to repair it yourself or simply buy another. I'd probably buy another lens.

[Mike Kovacs]

Try a single drop of acetone suspended from a screwdriver.

Those are CROSS heads, not phillips.  Use a cross head driver or a slotted driver on one of the two slots.  Phillips will strip it, guaranteed!

[JohnR]

Thanks Mike, I'll give that a try

[Ronald Bishop]

I have ground the point off a phillips to make cross head drivers. Use a driver with a hardened tip, then file it by hand. Don't try the cheapie screwdriver as they may not have tips hard enough and you will end up with a buggered screw head.

[JohnR]

Is cross head also known as Posi-drive?  :? These small drivers I have seem to fit the screws well enough...?

Anyway, the acetone worked! So, if the lens is stuffed anyway I figure I might as well pull it apart and learn something. Here is as far as I have got. I have removed the back plate and the aperture ring, and the rear element. The two screws left in the picture hold the bar that stops the lens rotating and makes it move up and down the helicoil. But removing them doesn't seem to get me any closer to disassembly. I've run out of screws to undo! What would come off next, something from the front of the lens? Any suggestions appreciated!

[JohnR]

HAH! I fixed it!! [JohnR does victory dance.]

Whether I can get it back together with the focusing ring lined up right is another matter... :oops:

Mike, synthetic grease on the helical? Like the kind used on bicycles? BTW what's best for cleaning the parts?

More pics in a bit :shock:

[Mike Kovacs]

So you've separated the helical?  Is it a single helical or a double helical? (the latter commonly used on lenses that do not rotate the front element when focused)  I sure hope you marked the helical separation point(s)!

I clean my helicals with solvent (usually lighter fluid) but if they are completely free from optics, I take them over to the sink and scrub the helicals with dish soap, rub them with #0000 steel wool, then dish soap again, rinse well, air dry.  The helicals should run together without hang-ups before you even grease them if you've cleaned them well.  Don't even think about steel wool and soapy water unless they are free from optical/diaphragm components.

There are different damping greases you can use that are probably the "most proper" but I use Schwinn synthetic bicycle grease on my helicals.  It gives them a medium level of drag.  I also have Dow Corning high vacuum grease (also low outgassing, full synthetic) but its very stiff - I use it for highly damped actions like non-click-stopped aperture selectors like those found on old Contax RF lenses.

After you get it back together, check out Mike Elek's lens collimation article - you need to verify infinity focus is correct, which it will be if you put it all back together the right way.

PS - what was wrong with it?  Did you straighten a dent?

[JohnR]

Yes, I couldn't see it, but when the outer barrel (with the grip) was removed, the binding stopped. So I applied some brute force with pliers wrapped in cloth to where the bump was. Now I have it reassembled and it sticks a little still between 2-3m, I will have another go on the weekend. I may drill out the holes holding the outer barrel on just a little, as that may allow me move it enough to get a little more clearance.

Anyway! It's a double helical, now you ask. I didn't realize that! I didn't mark it but the way the lens is built it's not too hard to tell if you've reinserted the lens element in the wrong orientation. Fortunately for me... Took a while for me to figure it out though The focus looks good (it's an SLR lens--do I still need the collimation thing?), I'll take it apart again this weekend and clean it properly following your advice. My baby is back (nearly)!!

[ImageMaker]

it's an SLR lens--do I still need the collimation thing?

Only if you want to be able to focus to both endpoints -- infinity (the horizon, the Moon, etc.) and whatever the close distance is on the scale.  Of course, it's rather nice to be able to just run it up to the stop and know it's focused to infinity and will be within DOF at f/16 down to, say, 8 feet.  That can only happen if you get it collimated correctly which, with double helical lenses (like my Varexon 135 mm) isn't as simple as it looks.  I need to try again on mine; it still won't focus on the Moon, though it's better than it was before I opened it to clean the aperture...

[JohnR]

Heh, it's more complicated than I thought :oops: In daylight I can see that it doesn't quite get to infinity. I need to think about which direction I need to rotate the outer helical when I re-insert it...