Monthly Archives: July 2015

Canon FD 800mm F5.6 L lens fungus removal

Warning! Altering camera lenses is unadvised and IS NOT recommended. If anyone should attempt to alter, fix, repair, work on or follow the steps I took to fix my lens I am not to be held responsible  for damages done to  your own lens. THIS BLOG POST ONLY DEMONSTRATES WHAT I DID TO FIX THIS LENS, THIS IS NOT AN INSTRUCTIONAL GUIDE BY ANY MEANS! DO NOT ATTEMPT!



canon fd 800mm f5.6 L LENS _PH-MIKE-KOTOWSKI





Wow! The legendary Canon fd 800mm f5.6L lens! I am so amazed at this lens optical performance and unique focusing design. This lens is a blast and gets 5stars!


Things to fix…Fungus inside the lens, stuck aperture, and the fd mount that was falling apart. Yikes!

I used the lens fist with a canon eos 1d markII camera body as well as a canon 7d, both digital camera bodies were used with the EDMIKA .7 fd-eos adapter which these adapters can be found here on ebay. I highly recommend these adapters for the use with fd lenses as I have used one with the canon fd 500mm f4.5L lens for a couple of years now and it works wonders! They are glassless, allowing optimal optical performance and obtain infinity focus when used on canon eos mount systems. Since the lens had multiple issues and I was forced to shoot everything at F5.6 for a while  that was not always the ideal f-STOP also as it was unsafe to mount a camera to the lens due to the lens damaged mount system it was time to work on this beast.


Cleaning of the first (front) element was the first task I wanted to tackle, as it was the simplest and least daunting, also would show instant results in IQ.

Thankfully the fungus was mainly on the back side of the first element (front element). To remove that element was a bit of work but every bit well worth it. Having over a 5″ diameter I decided to build a spanner type contraption to fit the slots that would allow me to safely remove the first element.

Steps I took to rid the first elements of fungus.


Step 1
measure the diameter of the slots


Step 2
I  marked a 1/2″ piece of plywood at the exact distance for the slots and drove nails into those marks, only allowing approx 3/4″ of the nails to go  through the back side board,  this allowed the nails to have enough depth to go into the slots with just enough room for me to see what was going on. also short enough for the nails to be strong  and not bend or flex while removing the element as it was hard to rotate.(I filed the ends of the nails to a point to act as a cleaner more precise instrument.)

canon-fd-800mm-nails-02-front-element_ph-mike-kotowski                                                   canon-fd-800mm-nails-01-front-element_ph-mike-kotowski

step 3
With cotton swabs soaked in 91% isopropyl alcohol I cleaned around the outside parameter of the element allowing the glues or any buildup to become free, allowing the first (front) element to rotate off easier.



step 4
I carefully and precisely inserted the nails into the slots of the element outer metal ring so that the glass element was not touched or scratched.

step 5
With firm even pressure, assured that the nails are in the slots, I slowly turned the plywood counter-clockwise, removing the element.


Step 6
Wearing lint free gloves and using a plastic knife guiding the lens element I was able to carefully turn the front of the lens down towards the ground, with gravity on my side, so that the element fell out into an opened hand, without touching the 2nd (inner element).




Step 7
Using a DATAVAC ELECTRIC DUSTER ED-500 I blew the lens element clear of any dust and loose debris, then cleaned the lens element with 91% isopropyl alcohol scrubbing the element gently with lots cotton swabs. Later using TIFFEN lens cleaning paper to mop up some liquids, finishing the cleaning of the element with a pearstone lens cleaning cloth and one last blow using the DATAVAC ELECTRIC DUSTER ED-500. These cleaning tools can be found at



Step 8
Making sure the lens element is completely clean and clear I then re-installed the lens element.








 step 9
I mounted my canon eos 1D mark II Dslr camera body and  shot these photos…

canon-800mm-fd-5 6 l_ph-mike-kotowski


















Thanks for checking out my project, stay tuned for a full review of this lens, more repairs and modifications I have done to this lens and others.

-Mike Kotowski