Lenses come in all shapes and sizes. Some look like flat pancakes, others are more boxy. Still others are long and tube-like. This variance in lens shapes can sometimes create challenges when it comes to maximizing usage of limited space in your camera bag, especially when trying to cram lots of lenses into a top-loading camera bag.

This problem is especially true with the Micro Four Thirds system, because compared to DSLR lenses, M43 lenses are approximately 3x smaller in both weight and size. The reduced size is great, but most top-loading camera bags have deep pockets to accommodate longer SLR lenses. But when you put smaller M43 lenses in a camera bag, you end up with a lot of wasted extra space. And it’s a bad idea to double stack your lenses on top of each other, According to Tracy AlChayeb they’ll bump into each other as you walk around.

Lots of wasted space in a deep camera bag pocket holding a M43 lens

So how can you use the space in your camera bag efficiently without damaging your lenses? The answer is by using a double-sided rear lens cap that lets you mount two lenses back-to-back. This innovation lets your double stack lenses in a secure way that lets you use all of the empty space in your bag and ensures your lenses won’t damage each other.

When your lenses are attached back-to-back, they won’t bump into each other


The DIY version and commercial version of a dual / double-sided lens cap side-by-side

Want to get your hands on a double-sided rear lens cap (sometimes called a “lens flipper”)? There are commercial products such as this double mount / reversible rear lens cap on Amazon. I bought one of these, and I made my own as well.

The biggest differences between the two are the fact that the commercial double lens cap is weather sealed, and it’s actually one solid piece of plastic. However, the commercial product is much thicker and harder to mount a lens to, as you need to get the alignment perfect (by lining up the red dot with a specific groove on the dual lens cap) and twist harder as if your were mounting a lens on a camera body.

How to make a DIY reversible / double lens cap mount

Fortunately, you can make your own DIY double lens mount cheaply with the help of a little super glue. If you want to go that route, here’s a link to buy an inexpensive set of two M43 rear lens caps – and they sent me the OEM Panasonic caps. For the thinnest option available, the OEM Olympus rear lens caps are what you want.

To attach the rear lens caps to each other, simply spread a thin layer of super glue on the backs both lens caps, making sure to cover all parts that might contact each other. Then press firmly against each other for 30 seconds or so. Then, set aside and let dry for 24 hours to allow the glue to reach it’s full strength.

How much space do you save with a lens flipper?

The end product of either option allows you to attach two smaller lenses together so you can fully utilize all of the space in your camera bag, potentially doubling the amount of lens storage you have. Practically speaking, I’m able to fit two more lenses in my small, top-loading bag than I was before (Think Tank Retrospective 5).

With two smaller lenses joined together, you can now use the same pockets you use to store your longer zoom lenses without wasting space. Here’s a side-by-side image of the Olympus 45mm f1.8 prime and the 12mm f2.0 prime joined together with the DIY dual lens cap compared to the Olympus 14-150 f4-5.6.

Another side-by-side comparison of the same Olympus primes joined together with the commercial reversible lens cap, compared with the Panasonic 100-300mm f4-5.6. Also pictured is the DIY lens flipper with the 17mm and 25mm Olympus primes.

Why double lens cap mounts are useful

One of the reasons I love M43 is because the system lets you carry lots of special purposes lenses in a small, light package. There’s physical space in your bag for lots of little lenses, but you have to worry about securing them so that they don’t bump into each other. This solution is perfect for that and it will definitely allow me to fit one or two extra lenses in my bag without having to worry about damaging them. With the help of these nifty reversible lens caps, I can carry a full kit around at all times in a tiny bag.

Final verdict? At the end of the day, whether you buy one or build one on your own, a lens flipper / double lens mount is worth trying out, especially if you have a lot of lenses for a mirrorless system.