| Author |
Message |
    
Martyp
Tinkerer
Username: Martyp
Post Number: 3
Registered: 12-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, September 05, 2009 - 04:23 am: | 
|
Hi all.
I need some advice in disassembling the front element. I'm not able to remove the name ring. It seems to be just glued in rather than screwed. I tried to turn it with a rubber sink stopper with no luck. Thanks in advance.
Regards, Marty. |
Tom_cheshire
Tinkerer
Username: Tom_cheshire
Post Number: 167
Registered: 04-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, September 05, 2009 - 04:39 pm: |
|
I cleaned the 135mm version of this. Yes, you do spin off the name ring and go from there. Try seeping a bit of lighter fluid around the edge to loosen things up and try again. If that doesn't work, drill two holes opposite each other with a tiny drill like a #80 or so and use a pin vise to spin it open. |
Glenn
Tinkerer
Username: Glenn
Post Number: 656
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, September 05, 2009 - 04:48 pm: |
|
I am pretty sure the ring is of the glued variety - you can check by pushing a 1/16" wide strip of thin plastic down between filter threads and outer edge of ring.
If the following seems overly complicated, then try and prise out the ring with a screwdriver - many do and leave horrible tell tales around the inner edge of the plastic ring. This is a definite no no as far as I am concerned, no mangled screw heads or tell tales on my repairs!
I have made a thin curved lever from a junior hacksaw blade to lift the glued rings out. Heat a scrap junior blade to red heat at one end and let cool slowly. Grind or file off the teeth and end with pin. File and polish the end and then bend the last 1/2" up approx 30 or 45 deg in a smooth curve. Reheat to red heat and harden out in cold water, use this tool carefully as being fully hardened it is somewhat brittle. If you want you can polish the fully hardened end, then gently heat the bend to a straw colour and leave to cool. This will give a more resilient tool.
To remove ring - fold up a nice pad of microfibre lens cloth and cover element, place end of lever under inner edge of ring and gently lever ring up. If the ring has been removed before, there could be a much larger glue line than the original Canon 3 or 4 dots - in this case instead of just levering straight up, very gently work the lever tip edge to edge. Do this very gently so as not to damage the inner edge of the plastic ring.
Done properly, this method will allow plastic rings to be removed without those horrible tell tale dings that are the give away to a bad DIY disassembly.
If you require any more advice on stripdown, I will have to dig the manuals out. I cannot remember if the 35mm f2 has an inner element that moves separately during focusing, shorter focal lengths certainly do and requre a little more thought when you work on them. |
Glenn
Tinkerer
Username: Glenn
Post Number: 657
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, September 05, 2009 - 05:12 pm: |
|
Tom may well be right, but the Canon manual does not state which ring is used on 35mm (Just dug them out). It does note that there were modifications (read cost cutting) made to the later production runs - different part numbers for certain parts, including name ring.
Before you drill holes in a stuck screwed ring, cut a ring of double sided adhesive tape and use a piece of carefully squared off PVC waste pipe. This sometimes gives better purchase than when a sink plug is used. |
Martyp
Tinkerer
Username: Martyp
Post Number: 4
Registered: 12-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, September 06, 2009 - 02:34 am: |
|
Thank you Tom and Glenn for your replies. I think will try asap the hacksaw blade trick.
Regards, Marty |
Martyp
Tinkerer
Username: Martyp
Post Number: 5
Registered: 12-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, September 06, 2009 - 04:46 am: |
|
I checked the threads with a thin piece of plastic
and discovered the name ring it's indeed screwed in place. So I followed Tom's advice and did seep a bit of lighter fluid with a syringe. That did the trick and I could unscrew the ring with the sink plug. The front element came off after removing the inner set of tree screws. The white speck I wanted to remove was sitting on the below element so no need to dig further in. I cleaned and reassembled. I mounted the lens to a body and seems to focus properly.
Thank you very much for the help.
Regards, Marty, |
