Regreasing Canon FL 35/2.8 - step by step instruction

[sceptic]

Being home with a fever, what better way of spending a few hours than regreasing a lens, documenting it and then post it online for others to (hopefully) benefit from?

I will try and point out crucial steps needed to avoid messing up, but also add some helpful, but not mandatory, things to make it as easy as possible.
As always, you regrease your lens at your own risk and I will not take any responsibilty for any mishap that may occur if you try this yourself.
Anyway, on with the show!

Step 1: Put the lens face down and unscrew the outer of the two retaining rings (the inner one keeps the rear lens(es) in place, leave it alone)

Regreasing Canon FL 35/2.5 by scepticswe, on Flickr

Step 2: Lift the focusing assembly up from the rest of the lens. No need for any markings at this point, they only fit together one way. The screw seen on the lett part of the separated lens fits inside the chrome-colored slot seen directly facing it on the right part:

Regreasing Canon FL 35/2.5 by scepticswe, on Flickr

Step 3: Mark the screw directly behind the infinity mark on the focusing scale (which also happens to be the one closest to the slot mentioned in Step 2) by scratching the metal just next to it. This is to ensure that the focusing grip is reinstalled correctly. Then dissolve the thread locket/laquer with acetone and unscrew the three screws holding the focusing grip to the brass helical.

Regreasing Canon FL 35/2.5 by scepticswe, on Flickr

Clean the focusing grip (mine had some dust/grit on the inside) and put it away.

You should now have something that looks like this:

Regreasing Canon FL 35/2.5 by scepticswe, on Flickr

Up to this point, there is not much that can go wrong. However, after the next step there is a risk of messing up if one is not careful.

A slight sidetrack, on "the nature of helicals": Generally, there are three parts (four, if you count the grip we just removed) that make up the focusing unit. A static part (the black part with the depth of field markings in the picture above) and two moving parts (one of which is the brass part seen above). The second moving part is threaded inside the brass part, and they both rotate when turning the focusing grip.

As often pointed out, it is important to mark the point at which two helicals separate (to be able to put them back again), but one thing I would like to stress is to also mark how far the two parts should be screwed together. Knowing these two parameters (where to start and when to stop turning) makes putting it all back together so much easier.

With that said, let's move on:
Step 4: Unscrew the hard stop, which prevents the helicals from turning past infinity or to unscrew completely.

Regreasing Canon FL 35/2.5 by scepticswe, on Flickr
Notice the two bright spots around the holes, these will help reinstalling the hard stop.

Step 5: Take notice of the brass guiding pin inside the helicals:

Regreasing Canon FL 35/2.5 by scepticswe, on Flickr
This pin keeps makes the barrel move forward/backward in stead of spinning when turning the focusing ring.

One crucial point is when the guiding pin "slips out" of its track, at which point the resistance to turning is greatly reduced. This is because after that point, you are no longer moving both the moving parts, but just one (the brass one).

As soon as the pin slips out, the inner (black) helical will stop to rotate, and just "follow along" as the brass helical is turned.

In order for the guiding pin to "find its way back" into the black, inner helical when reassembling, it is important to position the black helical correctly inside the brass one, before the brass helical is threaded back into the static, bottom part.

Step 6: Grab the top of the brass helical and, while watching the guiding pin, turn it until the pin just "disappears" under the black, inner helical:

Regreasing Canon FL 35/2.5 by scepticswe, on Flickr

If you keep turning, you will notice that the resistance is greatly reduced and that the black helical stops moving.
VERY IMPORTANT: Don't turn the black helical inside the brass one (at least not at this point).

Step 7: Mark the outside of the brass helical in line with the hard stop for minimum focusing distance, at the point at which the guide pin "slips out".

Regreasing Canon FL 35/2.5 by scepticswe, on Flickr
This will be a point of reference, in case you mess up.

Step 8: Carefully turn the brass helical until it comes out of the bottom part. Again, using the hard stop for MFD as reference, mark the outside of the brass helical. In my case, this happened to be exactly at a point where a mark was already made (the "P" in the picture)

Regreasing Canon FL 35/2.5 by scepticswe, on Flickr

Step 9: Mark the inside of the brass helical by putting scratches in line with the two sides of the "gap" in the inner, black helical. Be very careful not to move the black helical relative to the brass one while doing this. The point of this is to know how far the black helical should be screwed into the brass one when reassembling them.

Regreasing Canon FL 35/2.5 by scepticswe, on Flickr

Step 10: Unscrew the black helical from the brass one and mark the point of separation. I use the gap in the black helical as reference and mark the top of the brass helical with two scratches.

Regreasing Canon FL 35/2.5 by scepticswe, on Flickr

You now have all pieces separated and marked for reassembly. Clean the helicals as you see fit (I prefer dry cleaning with microfibre cloths to remove the bulk of the grease and finish with the same cloth with some solvent applied). Reassembly is simply following all the steps in reverse.

[Lloydy]

Excellent tutorial, very clear. That's not a lens I've got, but it's useful to see the methods used to mark the helicals etc.

[sceptic]

Thank you! The principle is similar for a lot of lenses. This example was fairly easy, especially since the brass helical is screwed all the way in when reassembling. For some other lenses, the brass helical is very finely threaded and not screwed all the way in (for instance, roughly three full turns out of a possible five). In those cases, one needs to keep track of how many turns it takes to unscrew the helical.

[cooltouch]

Thanks for this! I have an FL 35/2.5 and it is one of my favorite Canon lenses. Mine has a problem where the aperture iris blades are sluggish. I'm sure I'll be able to use some of your steps to get to where I need ot go.

[sceptic]

You're welcome! I'm afraid this guide is of little use to someone trying to clean the aperture blades (a part from the first step).
As a general suggestion for cleaning aperture blades, I would recommend cleaning the blades while still inside the lens barrel, to avoid the tedious task of reassembling the aperture blades. Simply remove all the lenses from the barrel, leaving you with a hollow metal tube with the aperture in the middle of it. Then, drop a few drops of some petroleum-based solvent (naphta, lighter fluid, white spirits) directly onto the blades and let it seep into the surrounding housing. The idea is to dissolve the oil into the naphta and let it drip straight through the lens (put a suitable tray or pan underneath). Work the aperture pin on the back of the lens (opening /closing the blades) while the blades are wet, to get the naphta to reach all parts of the aperture. Add more drops of solvent as needed and finish by evaporating the solvent by blowing with a blower bulb.