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MOUNT UNIT


NLsafari

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<p>I just had my Canon FD 300/2.8 FLUORITE evaluated for sticking shutter blades which I posted a few weeks ago. It turns out that it is not the shutter blades that is causing a problem but it is the mount unit that is defective. I don't know for sure but I assume the mount unit contains the small metallic arm that goes into the camera body and is activated when the shutter is released. This lens is a beauty the body is clean and the optics are mint. Hence, I have to find a way to either replace ( from a similar lens ) or repair the mount unit. I was thinking of using S.K. Grimes to machine the parts that have to be replaced. They machined an adapter for this lens so that a standard size filter could be fitted in front of the first element. Canon used an odd ball thread size for the front of the lens and no off the shelf filter can be used . I am open to suggestions for a way to solve this problem.</p>

<p>Raphael</p>

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<p>No. The "mount unit" is that part of the lens that contains the aperture signal lever and closes the shutter blades to the specified F/stop. I think that if the lever binds it will not return completely to the resting position and the shutter blades could stay partially closed instead of being completely open at rest. This is what I see happening to the diaphragm opening when I put the lens on the F-1n and look through the front. A stiff lever could also cause a sluggish diaphragm which I also see. I have never opened up a Canon lens but I think since the lever is not totally frozen this problem might be repaired with a little cleaning and lub. I am asking for ideas to solve this problem.</p>

<p>Raphael</p>

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<p>OK, I was confused. You’re talking about the aperture actuating mechanism. It’s made up of levers, cams, etc. that are spring-loaded. When you press the shutter button on the camera, the aperture stop-down lever in the camera moves the stop-down lever on the lens. All of the of the internal lens levers move in concert to stop the lens down to the desired aperture, then open it up. Something internal is out of adjustment or some of the internal lubricant has dried out making things stick. You won’t be able to figure out what’s wrong until you open it up. I suggest you buy a 300/2.8 repair manual off eBay before doing anything. A repair manual will have a internal schematic which will help you diagnose your problem. I have one for my FL-F 500/5.6 which has proven to be very helpful when my lens needed a slight adjustment.</p>
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<p>Rick, I don't think he took it apart although I did not ask him if he did. The tech tried to get the "mount unit " from Canon but it was not available. How tricky is it to take the "mount unit" apart to better evaluate the root cause of the problem without making matters worst?<br>

Raphael</p>

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<p>Jim, Good idea . I looked in ebay and did not find any. Let me know if one is available some where. Since I don't plan to dismantle the lens , I don't want to learn on a rare piece of glass like the FLUORITE, do you think another camera tech could figure things out without the manual and get it right without doing harm? I know this is not a fair question because it is like asking if a routine eye surgery can go wrong.</p>

<p>Raphael</p>

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I would be extremely surprised if it could not be disassembled for servicing by a qualified technician.

 

Ken Oikawa is awesome. A few years back I was unable to reach him so my own pristine FD 300/2.8 SSC Fluorite was

sent to Steve at Camera Clinic in Sparks, NV for servicing. One specific problem it had was excessive play in the focusing

mechanism, which Steve solved. I know he did a major disassembly so he's certainly acquainted with the internals!

 

Gus Lazzari would be another top pick, on the East Coast.

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  • 2 months later...
A few months ago I posted a problem with my Canon FD 300/2.8 SSC Fluorite which had shutter blades that were sticking. I sent the lens to a few people and the problem was narrowed down to the aperture actuating mechanism. They how ever were reluctant to open up such a rare piece of glass and try to fix the lens. Finally I sent the lens to Steve Sweringen at Camera Clinic in Mandan , ND (775 829 2244 ) who serviced the lens. I just got the lens yesterday and the shutter works perfectly.
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A few months ago I posted a problem with my Canon FD 300/2.8 SSC Fluorite which had shutter blades that were sticking. I sent the lens to a few people and the problem was narrowed down to the aperture actuating mechanism. They how ever were reluctant to open up such a rare piece of glass and try to fix the lens. Finally I sent the lens to Steve Sweringen at Camera Clinic in Mandan , ND (775 829 2244 ) who serviced the lens. I just got the lens yesterday and the shutter works perfectly.

 

Raphael

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I'll second the suggestion to send your lens to either Ken Oikawa or Steve in Sparks, NV. Both are very capable Canon repair techs and both have an excellent reputation.

 

It is not difficult to dismantle a breechlock mechanism on the old Canon breechlock lenses. But you still will need a good set of tools and patience to make sure the job is done right. If you elect to do it yourself, take frequent pics of the disassembly process with a digital camera so you'll know how things go back together. I also recommend that you do the dismantling over a hand towel or equivalent. It's a good idea to have carpet on the floor too, just in case. Those tiny screws and what have you have an incredible propensity for bouncing and rolling right off a table and disappearing into a parallel dimension, never to be seen again.

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I'll second the suggestion to send your lens to either Ken Oikawa or Steve in Sparks, NV. Both are very capable Canon repair techs and both have an excellent reputation.

 

It is not difficult to dismantle a breechlock mechanism on the old Canon breechlock lenses. But you still will need a good set of tools and patience to make sure the job is done right. If you elect to do it yourself, take frequent pics of the disassembly process with a digital camera so you'll know how things go back together. I also recommend that you do the dismantling over a hand towel or equivalent. It's a good idea to have carpet on the floor too, just in case. Those tiny screws and what have you have an incredible propensity for bouncing and rolling right off a table and disappearing into a parallel dimension, never to be seen again.

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  • 1 year later...
<p>OK, I was confused. You’re talking about the aperture actuating mechanism. It’s made up of levers, cams, etc. that are spring-loaded. When you press the shutter button on the camera, the aperture stop-down lever in the camera moves the stop-down lever on the lens. All of the of the internal lens levers move in concert to stop the lens down to the desired aperture, then open it up. Something internal is out of adjustment or some of the internal lubricant has dried out making things stick. You won’t be able to figure out what’s wrong until you open it up. I suggest you buy a 300/2.8 repair manual off eBay before doing anything. A repair manual will have a internal schematic which will help you diagnose your problem. I have one for my FL-F 500/5.6 which has proven to be very helpful when my lens needed a slight adjustment.</p>

Hi Jim, Is there a specific lubricant that should be used to lubricate the aperture actuating mechanism and the internals of the Canon FD Fluorite 300 so that it does not dry out and stick ?

 

Raphael

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  • 2 weeks later...
I would recommend assembling the unit dry, without any lubricant, and see how it behaves. I say this because any excess lube is gonna migrate down to the iris engagement mechanism and eventually onto the iris blades, resulting in sluggish or frozen performance. If it appears that lube is necessary, then I suggest using a very light lubricant, such as sewing machine oil, and then touching no more than a drop to the pivot points only in the mechanism.
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