Disassembly of focusing helicals on a Canon FL 35/2.5 - step by step instructions

[scepticswe]

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 (sorry for the underexposed image):

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

 

[scepticswe]

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.

 

[Nodda Duma]

Great write-up.

You mentioned re-greasing and I thought I'd share some inside info on this topic. Maybe folks have heard about this and maybe not, but here goes.

For focusing rings, the lubricant of choice is damping grease. Damping grease provides for a smooth feel without slippage and without slop. The grease I've used in the past (and I think is the common one in the industry) is the Nye brand of damping greases. There are a range of viscosities available depending on the specific feel you are going for, ranging from a light dampening to heavy dampening of the movement. Unlike silicon-based lubricants, Nye damping grease (and maybe others?) does not creep... a major reason why I've used it in the past. You do not want your lubricant creeping over time into your optical barrel and onto your optics.

You can google search and find their products. I believe they provide a sample kit of small packets of a range of damping greases, as well as a kit with larger volumes of grease. If I remember correctly, I purchased a kit with 10 jars of grease that I used for several years when I worked for the Navy.

Regards,
Jason

 

[scepticswe]

Thank you! I use Helimax XP helical grease and some non descript grease I got as a free sample from a grease company that thought it would suit my needs.

 

[David Lyga]

For years and years I have, after thoroughly cleaning the helicoid, used a dab of Vaseline. I have never had anything but good luck with this. - David Lyga

 

[Nodda Duma]

Disassembly of focusing helicals on a Canon FL 35/2.5 - step by step instruct...

For years and years I have, after thoroughly cleaning the helicoid, used a dab of Vaseline. I have never had anything but good luck with this. - David Lyga

I can't recommend using Vaseline because it liquifies when hot and hardens when really cold. If your lens is only ever exposed to moderate temperatures then Vaseline is a perfectly suitable substitute. Otherwise just get the free samples of proper damping grease from Nye. Free is cheaper than Vaseline and it works more better.

 

[David Lyga]

If you use only a tiny bit of Vaseline you have no problem with either cold or hot. All I can do is speak from experience. I do not know, maybe NYE is better, but I am quite critical with what I put on my lenses and, as I said, a bit will do no harm. - David Lyga

 

[E. von Hoegh]

If you use only a tiny bit of Vaseline you have no problem with either cold or hot. All I can do is speak from experience. I do not know, maybe NYE is better, but I am quite critical with what I put on my lenses and, as I said, a bit will do no harm. - David Lyga

Vaseline is actually quite a good lubricant. However, this morning at 6:15 or so am it was -24of here, and you would probably not have been able to focus a helicoid lubricated with it. I have three different weights of the Nye damping grease and it really is the only stuff to use. Second best is some translucent red grease I bought almost 20 years ago, the original packing is long gone but it doesn't creep, deals well with extreme cold, and gives a nice feel. I'll see if I can figure out what it is, it's an industrial product.

 

[David Lyga]

Vaseline is actually quite a good lubricant. However, this morning at 6:15 or so am it was -24of here, and you would probably not have been able to focus a helicoid lubricated with it.

I know what you are talking about, but if you use only a tiny bit of Vaseline, you will have no problems. The important part to NOT put much lubricant is on the very narrow threads which provide SUPPORT for the helicoid. - David Lyga

 

[John Koehrer]

^^^^^^^^In the army we said there were three ways of doing things. The right way, the wrong way and the Army way.
There's always a rational for any of them. SUPPORT???? Never heard that one before.