Disassembling FDn 200mm f2.8 IF

Hi I'm new to the forum and have gotten valuable information in the last several weeks as I've taken the plunge into the canon fd realm. I recently bought an FDn 200mm f2.8 IF that looks to have some minor fungus growth. It's not super obvious on how to disassemble it so before experimenting I was wondering if someone could give some hints on how it's done. Thanks.

If you are not an expert please do not take it apart. Give it to someone who is an expert tech. I speak as one who is

sadder but wiser.

<p>You need to start with practice on dis-assembly and re-assembly and repairs with something less valuable, for sure.</p>

<p>Taking apart is not very difficult, but <em>putting together again</em> is another matter altogether -- also a voice of experience speaking here. :|</p>

<p>If you are bound to do this, start at places like our very own Rick Oleson's page<br /> http://rick_oleson.tripod.com/index-27.html</p>

<p>Thanks for your responses. I will take the risk. I've done my fair share of disassemblying in the past and I'm ok if I turn it to a brick. I just thought some here may have taken the 200/2.8 IF apart and could point me in the right direction. I checked out Rick's page but couldn't find what I was looking for. I will keep looking.</p>

<p >I would advise getting a factory shop manual. You can pick them up on eBay for not much money. I picked up several FD repair manuals several years back and they do help in explaining how a lens is assembled. Very helpful diagrams too.</p>

"Tickling the dragon's tail"

Thank you, Jim. I will do that.

<p>I thought about disassembling a 400mm f/4.5 IF I owned, and brought the subject up in the now defunct KY Repair forum. It was quickly brought to my attention that without a set of very specialized optical measurement tools, I'd never get the IF assembly back together so it would work right. Instead I decided I'd send it off to -- oh, what's his name, the Japanese FD expert that everybody here sends their lenses to? His price is quite reasonable, so that's what I'd recommend you do, unless you really and truly want to turn your 200/2.8 IF into a brick.</p>

<p> </p>

<p>If you are not well acquainted with that lens and qualified to repair it, I would NOT take it apart. Leave it to someone who is a Canon authorized repairman.</p>

<p>I just got a response back from the great Gus, Gus Lazarri. on this type of lens. I thought it was worth while mentioning here in this thread.</p>

<p>He seems famous and very professional about his SLR repairs. <br /> Tthis is what he emailed me when I asked him if it was worth to let him do a CLA on the Canon Nfd 200mm f:2.8 IF.</p>

<p><em>First of all thank you for finding me.</em><br>

<em>The following email should answer </em> <em>most of</em> <em>your questions:</em> <em>As for the canon NFD 200mm f2.8, because of the extensive use of a combination of polycarbonate and adhesives (loctite), this version is extremely difficult to conduct a tear-down. </em> <em>Parts may be required if some of the tear-down results in parts breakage/damage; problem is that Canon no longer sells parts for this 200mm.</em><br>

Gus seems to be a very busy man also, as his website http://tlccamerarepair.homestead.com/ states that they are not taking new repairs until oct 2015.He was however still responding to the email I sent him. I would take his advice. It seems that these lenses are very hard to repair and if you don't have the spare parts... I would take the loss and leave mine as it is or buy a different one if its too far gone. My Version seems to have a lot of Haze in the Middle elements, and would be hard to repair. Maybe the use of the adhesives itself used on this type of lens is generating the Haze over time.</p>

Just some thoughts on this topic for future reference.

 

I disassembled a Canon FDn 300mm f4 IF lens for aperture diaphragm cleaning. Its construction is very similar if not identical to my FDn 200mm f2.8 IF lens so it could be assumed the tear-down procedure is the same. This would apply to gaining access to the lens elements in front of the diaphragm assembly. The rear elements are part of the internal focusing mechanism and should not be tampered with.

 

There are two sections of the lens barrel containing lens elements in front of the focus ring. The front section with built in hood unscrews after loosening three tiny grub screws visible once the hood is slipped forward, this contains the large front elements. The mid section which has a narrow sharp taper, unscrews after slackening off three tiny grub screws under the front of the focus ring. These are accessed by sliding back the rubber grip, rotating the ring until six slotted grub screws are visible in the three oval cutouts. The frontmost three screws lock the mid section in place therefore need to be fully loosened, the rearmost screws hold the diaphragm unit in place.

 

The hard part was unscrewing these lens barrel sections as considerable turning torque was needed to release the threads. The front part came away eventually using rubber gloves for grip, but the mid section proved to be a real trial requiring various experiments with clamping the mid section and rear barrel plus using a heat gun at temps of up to 100 degrees celcius.

Ko Chu was a big help to me as I performed CLA on my Canon 400mm f/4.5 nFD lens. After removing the drop-in filter, I slipped the focus ring rubber downward until it was about 90% off the focus ring. This exposed the 3 set (grub) screws and once I loosened them I could easily unscrew the front lens assembly. Then I could remove one screw that secured an "idler" to the moving rear lens group and slide it out carefully. I was able to clean the rear lens group and reinstall it and replaced the worn idler that caused significant focus backlash. I did NOT see any Polycarbonate or Loctite in my lens. Based on my success I have purchased a Canon 200mm f/2.8 nFD and feel I can do the CLA if required. BTW, the Canon 400mm f/4.5 is quite a nice lens with very little CA for subject in the focus plane. There is longitudinal CA on foreground and background objects. I hope to post a Youtube video of my CLA procedure. Thank you.

I feel it important to point out you guys are commenting on a 3 year old thread. Carry on.