p.1 #1 · RRS Lens foot always loose on Canon EF 100-400 II lens. Is yours tight?
I bought a used Canon EF 100-400 II which came with a Really Right Stuff lens foot, LCF-54.
After using it for a couple years, I recently noticed that the lens/camera will easily swivel slightly left/right when mounted on a tripod. Maybe 1/20th of the frame width when zoomed to 400mm so it's difficult to keep the exact same frame when using the camera.
RRS suggested I check if the Canon lens mount screws were loose but they were tight. I replaced the RRS foot with the original Canon foot and there is only a slight give but little to no movement. RRS then suggested that the foot maybe worn or damaged and out of spec and that they could measure it if I mailed it back to them. I declined as I would still need to buy a new foot. RRS said the foot is about 10 years old based on the old logo printed on it.
When I look at the RRS foot, I see that the mating bottom is flat while the Canon side mount is curved or tapered on the ends. So the RRS foot only touches the flat middle region of the Canon mount which leaves gaps toward the edges of the mount. The original canon lens foot has a curve profile exactly matching the lens mount profile so it's a snug fit, no gaps, no twisting.
If any of you have this RRS foot and Canon lens, is your foot tight if you try to try to twist or swivel it? If it is tight, then likely my lens foot is worn or bent. I may try putting in a brass shim or plastic repair filler to fill in the gap between the RRS lens foot and the Canon mount.
p.1 #2 · RRS Lens foot always loose on Canon EF 100-400 II lens. Is yours tight?
I have the 100-400II and the RRS foot. I just checked it and it’s completely tight. I tried moving it while mounted on a tripod, and also tried checking for movement grasping it by hand off the tripod. In both cases, there is no play between the foot and the body of the lens. I also don’t recall ever making adjustments to the foot to tighten it.
p.1 #3 · RRS Lens foot always loose on Canon EF 100-400 II lens. Is yours tight?
The tripod mount sub-assembly screws are probably loose. The foot doesn't screw directly into the frame of the lens mount ring, it screws into a 1/4" threaded hole (as usual), which is set in plastic, and attached to the lens frame by four tiny screws. Design of the century.
This was a topic of active discussion when the lens was new; some people stripped the tiny screw heads (JIS, not Philips), some stripped the tiny screw threads, some tried to attach the foot or a rail using a slightly too long bolt, and it exploded the whole sub-assembly, which cracked when a tiny bit of torque was applied to the bottomed-out bolt.
Anyway, it should be an easy fix. Remove the foot and check the four tiny screws. Using a bit of blue Loctite would not be a mistake.
p.1 #4 · RRS Lens foot always loose on Canon EF 100-400 II lens. Is yours tight?
ct1co2 wrote:
I have the 100-400II and the RRS foot. I just checked it and it’s completely tight. I tried moving it while mounted on a tripod, and also tried checking for movement grasping it by hand off the tripod. In both cases, there is no play between the foot and the body of the lens. I also don’t recall ever making adjustments to the foot to tighten it.
Thanks for checking. Good to know the design works. So the issue is likely just my lens foot and lens.
p.1 #5 · RRS Lens foot always loose on Canon EF 100-400 II lens. Is yours tight?
jcolwell wrote:
The tripod mount sub-assembly screws are probably loose. The foot doesn't screw directly into the frame of the lens mount ring, it screws into a 1/4" threaded hole (as usual), which is set in plastic, and attached to the lens frame by four tiny screws. Design of the century.
This was a topic of active discussion when the lens was new; some people stripped the tiny screw heads (JIS, not Philips), some stripped the tiny screw threads, some tried to attach the foot or a rail using a slightly too long bolt, and it exploded the whole sub-assembly, which cracked when a tiny bit of torque was applied to the bottomed-out bolt.
Anyway, it should be an easy fix. Remove the foot and check the four tiny screws. Using a bit of blue Loctite would not be a mistake....Show more →
Thanks for the suggestion. RRS also made the same suggestion. I checked the screws using a regular phillips but the screws were not loose. I didn't torque the phillips too much knowing that I should use a JIS. I also tried the original Canon lens foot that came with the lens and it was tight. No play. If those small screws were loose, wouldn't the original Canon foot also feel loose? I'll look for a JIS to see if they can be tightened further.
p.1 #6 · RRS Lens foot always loose on Canon EF 100-400 II lens. Is yours tight?
As Jim said, remove the four screws, put a bit of Loctite on them and screw them back in.
I have two of the 100-400 IS IIs and there have been no further issues. I use the Kirk feet for the low profiles.
p.1 #7 · RRS Lens foot always loose on Canon EF 100-400 II lens. Is yours tight?
The screws to attach the foot might be a little too long. It is easy to file off a little bit from the end. Attach a nut to the screw shaft, file off 1 mm then remove the nut. The nut should clean up any roughness where you filed.
p.1 #8 · RRS Lens foot always loose on Canon EF 100-400 II lens. Is yours tight?
jmckayak wrote:
The screws to attach the foot might be a little too long. It is easy to file off a little bit from the end. Attach a nut to the screw shaft, file off 1 mm then remove the nut. The nut should clean up any roughness where you filed.
p.1 #10 · RRS Lens foot always loose on Canon EF 100-400 II lens. Is yours tight?
jmckayak wrote:
The screws to attach the foot might be a little too long. It is easy to file off a little bit from the end. Attach a nut to the screw shaft, file off 1 mm then remove the nut. The nut should clean up any roughness where you filed.
I removed the screw completely and added a spring washer (spacer) which would do the same thing as filing down the screw tip. It didn't improve things as the foot still wiggles slightly. It was worth a try.
I also got JIS screwdrivers and checked that all the four small screws on the lens mount subassembly were tight, they were. Just in case, I then added blue Loctite so they stay tight.
Thanks.
p.1 #11 · RRS Lens foot always loose on Canon EF 100-400 II lens. Is yours tight?
EB-1 wrote:
As Jim said, remove the four screws, put a bit of Loctite on them and screw them back in.
I have two of the 100-400 IS IIs and there have been no further issues. I use the Kirk feet for the low profiles.
EBH
The Kirk feet has the same curved contour as the original Canon foot so I can see how it would be a tight fit and not have any give. The RRS foot is flat where it mates or touches the Canon mount subassembly. I can see gaps along the edges unlike the original canon foot. I believe this allows the small amount of swivel if you torque the foot hard enough.
p.1 #12 · RRS Lens foot always loose on Canon EF 100-400 II lens. Is yours tight?
That would not surprise me. I put the Kirk feet on after getting the pair of 100-400 IIs in late 2014 and they never rotate. The built-in tripod collar of the 100-400 II is quite nice, especially compared to the crap they foisted on us with the RF 100-500.
