Hack to Make RF Rear Lens Cap work by feel (like an an EF cap)

Below is a hack I tried to may an RF cap work more like an EF cap, so you don't have to visually line up the mark on the cap with the mark on the rear of the lens. You can take the cap on and off by feel without looking at the lens or the cap.

I started by making a 3-D model of the old cap and then seeing if there was a way to cut the tabs down where there would still be 3 tabs left while at the same time fitting onto the bottom of the lens.

There was a solution, and I 3-D printed a custom cap that worked. But then figured it would be cleaner (not wanting to cause any junk onto the back of the lens that might make it to the camera's sensor) and easier to cut down the tabs on either a Canon or a 3rd party rear lens cap.

I 3-D printed a plastic template (I have posted a paper printable version at the end). I just the template, and I score where to cut with a sharp knife. You also have to cut down the one "stop" that prevents you from overrotating when removing the cap (more on that in a bit).

The 3 images below show the process of modifying a (3-D party) rear lens cap.

I used some diagonal flush cutters and a hobby knife to cut off the ears and the stop tab. There is not a lot that needs cutting.

Cutting off the "stop tab" (which prevents over-rotation when removing the cap) while supporting the 3-Way universal orientation will allow you to over-rotate and relock the cap when removing, but this will only happen if you are not simultaneously putting a little outward force to remove the cap.

If you try this, I would highly recommend cleaning the cap well after all the cutting to eliminate any loose particles.

The resultant modified RF cap will work on either RF or EF lenses. The same template can make an EF cap work on an RF lens, but note the RF cap will protect the seal rubber on "L" lenses where the EF cap does not.

Below is a hopefully-to-scale template (if the posting process does not strip the scaling).

Paper Printable Template

This may have been done before because it seems obvious, but I have not seen it.

Surely you can already orientate the cap by feeling the groove that Canon kindly put on the edge?

Karl_Guttag wrote:

Below is a hack I tried to may an RF cap work more like an EF cap, so you don't have to visually line up the mark on the cap with the mark on the rear of the lens. You can take the cap on and off by feel without looking at the lens or the cap.

This may have been done before because it seems obvious, but I have not seen it.

This has been mentioned before, but nobody has provided such good and detailed instructions before. Thank you.

I'm surprised that no 3rd party has started producing "universal orientation" lens caps yet. I guess it's easier to copy slavishly rather than do it a better way.

RDKirk wrote:

Karl_Guttag wrote:

Below is a hack I tried to may an RF cap work more like an EF cap, so you don't have to visually line up the mark on the cap with the mark on the rear of the lens. You can take the cap on and off by feel without looking at the lens or the cap.

This may have been done before because it seems obvious, but I have not seen it.

This has been mentioned before, but nobody has provided such good and detailed instructions before. Thank you.

I'm surprised that no 3rd party has started producing "universal orientation" lens caps yet. I guess it's easier to copy slavishly rather than do it a better way.

Thanks,

I had not seen directions for how to do it. It does help to have a computer model/drawing to see where to make the cuts. It's not a perfect solution in that there are no stops when taking the cap off, and you can turn the cap on more than you really need to when putting it on.

What I would do as a manufacturer is to make a version that works like a spring-loaded front lens cap. It would snap on and then press a button/lever to take it off.  Or maybe just spring-loaded ball bearings for a snap-on and snap-off type cap. I thought of doing it myself with plastic, but I was worried about the plastic getting shaved off and eventually finding its way into the camera body.

It would have been best if Canon had kept symmetrical ear spacing and symmetrical cap. They still could have changed the size/shape of the ears to prevent accidentally putting an EF lens on an RF body.

I did that with some EF caps. Works - but not very well, so I put them on some rarely used lenses or adapter rings.

CameraCarl wrote:

I haven't figured it out yet. Please tell me how you do it without looking at your lens and searching for the tiny red alignment line.

For Canon RF non-STM lenses I've seen the lens's Red Alignment dot aligns with the "AF/MF" switch.

The Canon RF STM lenses I've have the lens' Red Alignment dot aligns with the "Control/Focus" switch.

With the RF STM lenses I have I place my left thumb on the lens' "Control/Focus" switch, and place my right hand thumb on the lens cap's notch**, when attaching the lens cap I just align my thumbs. ** (have cut a self-adhesive white label to fit the RF lens cap notch to easily see the notch even in low lighting)

Grant not as eloquent as the OP's method, but works.

Nimonus wrote:

Rear lens cup from laowa is unisex, works on both.

Yes I noticed that too!

tkbslc wrote:

hedleyw wrote:

Surely you can already orientate the cap by feeling the groove that Canon kindly put on the edge?

Sure you can feel the groove on the cap, but how do you tell where it is oriented vs the lens? I'd love to know, because have essentially given up recapping my lenses in the field.

15 years shooting Canon EF and Panasonic and never once thinking about the lens caps because they just go on without thought. Now RF it's like trying to plug in a USB flash drive correctly on the first try.

It lines up with the red dot on the camera, I know where that is by now. Admittedly it’s not as easy as with the EF caps.