300mm F4 Error 1 with EOS-R

Hello,

Yesterday all of a sudden my 300mm F4 (edit IS) lens refused to work with my EOS-R camera. I kept getting the Error 1 faulty connection error. I am using a Canon adapter. I tried turning camera off and on, disconnecting the adapter and lens and re-attaching and gently wiping contacts with a cloth meant for eye glasses. Nothing worked. Then I sprayed a tiny amount of isopropyl alcohol on the wipe and wiped the contacts and made sure they were dry before reconnecting everything. I was able to take 6 or so pictures, before the error came back. I attached a Sigma 35mm art lens and was able to use it for over an hour without a problem, so I think I can eliminate the camera and adapter as the source of the problem.

I have read some people clean the contacts with a pencil eraser. Should I try that?

I called LensRentals.com and talked to their tech support to see if they have experienced this. They said that if one of the contacts has moved even a millimeter that could cause a problem. Below are some pictures I took of the contacts. I cannot tell if the contacts are level or not. He said I may need a new rear mount installed by Canon.

Is there anything else I can try? Has anyone had a rear mount replaced on this type of lens recently? Hoping that if I need this done it will not cost more than a few hundred.

Any help would be appreciated. I am on a month long trip to NYC and brought this as my only telephoto to use for birding. I may need to rent the 800mm RF again if I cannot fix this myself.

Thanks!
Chip

UPDATE:
I have seen other posts talking about a busted Flex cable / aperture mechanism. It seems that all of these posts refer to zoom lenses. Does this apply to my prime lens?

Update 2:
First, I have the newer IS version of the lens not the one from 1990s. Second, on a whim I went and put the lens back on my EOS-R and surprise it seems to work! I have taken several bursts of 10 photos each without a problem. I am thinking about taking a bus to a nearby park and testing it out for a few hours. Just hope it doesn't wink out on me. Maybe a good nights sleep solved the problem, jk? Maybe my cleaning combined with a long power off fixed it? I will keep you posted.

I'm glad to hear the lens is working again and hope it continues to do so.

There appear to be no problems with the contacts on the rear of the lens. I might check that the bayonet mounts on both lens and the adapter are secure. If those loosen, there might be interruption of the communication between lens and camera.

Carefully clean the contacts with a lint free rag dampened a couple drops of isopropyl alcohol (rubbing alcohol is fine for this purpose... lens or sensor cleaning fluid also can be used).

More often than not, when the electronic contacts are "dirty", it's finger oils. The alcohol will remove any oils on them.

Even though some people do so, I do not recommend using a pencil eraser. Those are made from vegetable oil... and it is probably oils that you're trying to remove. There's also some small risk with an eraser of a flake of it getting into the camera mechanisms, or of scratching the contacts (which are gold plated... because gold doesn't oxidize).

Thanks for your feedback amfoto1.

Unfortunately, the lens stopped working after a dozen or so shots. I tried multiple times of rebooting, removing the batteries, detaching and reattaching the lenses/adapters and the most I could get is a couple of shots. I cleaned the contacts exactly as you suggested.

This afternoon on a whim I decided to add my Canon 1.4x III teleconverter into the equation. When I connected the lens to the teleconverter, the camera worked fine indoors. So I took it to the Bronx Zoo and it worked for 3 hours without a hitch! When I got home I removed the teleconverter and the dreaded Error 1 popped up on the first exposure. So maybe my adapter contacts are slightly off? But I have not seen a problem using my Sigma 35 or Rokinon 14 with the same adapter.

One other point, somewhere, possibly in this forum, I read a comment from someone who said you should always detach any large lens from your camera when storing and transporting the gear. He said the weight and center of gravity of a DSLR with a large lens puts pressure on the mount that can cause problems long term. Are you familiar with this? I always keep my long lens attached to the body when driving to my sites. I also use a BlackRapid strap that I attach to my camera body (technically the battery grip). So when I am hiking around for hours the camera swings around a little and the weight of the lens is on the mount. Today I kept the lens and teleconverter separate and assembled everything at the zoo. I also attached the BlackRapid strap to the tripod mount on the 300F4. Definitely felt weird walking around with the camera this way, but I think it takes pressure off the mount. Thoughts on this?

MrChip wrote in post #19516675
...One other point, somewhere, possibly in this forum, I read a comment from someone who said you should always detach any large lens from your camera when storing and transporting the gear. He said the weight and center of gravity of a DSLR with a large lens puts pressure on the mount that can cause problems long term. Are you familiar with this? I always keep my long lens attached to the body when driving to my sites. I also use a BlackRapid strap that I attach to my camera body (technically the battery grip). So when I am hiking around for hours the camera swings around a little and the weight of the lens is on the mount. Today I kept the lens and teleconverter separate and assembled everything at the zoo. I also attached the BlackRapid strap to the tripod mount on the 300F4. Definitely felt weird walking around with the camera this way, but I think it takes pressure off the mount. Thoughts on this?

I have used Canon EF 300mm f/4L IS USM extensively on my DSLRs with no particular care or concern. Almost always handheld... very rarely on a monopod or tripod with a gimbal head.

At under 3 lb., the 300mm f/4L is lighter than several of my other lenses: EF 100-400mm II weighs 3.5 lb. (also no special care using it, often hand held). EF 300mm f/2.8 and 500mm f/4 are my "heavyweights" at about 6 and 8 lb. respectively. Those have their own straps, which I use in conjunction with the camera's strap. When not using the strap, hand carrying the rig, I do so using the tripod mounting foot as a handle. The camera is the lighter part of the equation (about 2 lb., with battery grip, dual batteries).

I often transport with lenses installed... sometimes drive with the camera and lens sitting on passenger seat.

I do not leave camera and lens on a tripod or monopod when moving any distance. It is too easy for things to loosen up when casually carrying with the gear on a tripod or monopod slung over one shoulder. I've had a few close calls... And there's no excuse, since I have quick release plates and platforms on everything. Note: I do move gear while it's on a tripod/monopod short distances, such as repositioning at a sporting event. But I don't do what I see some photographers doing...

I have a similar problem with my Canon 70-200L f/2.8 IS II, it has an "erratic" feel. It goes from manual focus to autofocus and vice versa like crazy (without moving any switch), I have to detach and reattach the lens for it to work (sometimes it works on the first try, sometimes it works after a few ones).

Then when I have IS ON and I autofocus, it moves the crystals of the lens, I can see them bumping through the electronic viewfinder, I have to zoom all the way out every time it happens to make the IS work, risking the lens from going to Manual Focus/Auto Focus.

I think the issue is with the adapter as the lens works perfectly with a DSLR. Don't know if it has to do with the fact that longer lenses are front heavy and they "lose" connection because they move the adapter from the camera or the lens by milimiters. I would try to grab the lens and while holding it "squeeze" it towards the camera as if you were trying to keep the lens firmly attached to the adapter and camera.

The sensor of my R6 got damaged by laser and they changed the RF mount ring on the camera, even with a new contact ring the 70-200 still made those problems.


I hope you/we find a solution, I stoped looking for a resolution after I bought a Yongnuo RF 85mm f/1.8 which I can use with crop if I need more tight shots (not a substitute for a 70-200 but it does the job).