Blackmagic Forum

Is it me or does the BMPCC4K lens mount give a little bit too much in an up and down movement, especially with lens wobble using a follow focus? Also, when I attach a lens support I notice I can reasily push the lens up a fraction of an inch. All of my BMPCC4K cameras do this. Anyone else notice this? Had it been designed this way?

A flaw of the mount. I used electrical tape on my camera to stabilize my lenses.

shim rings might also help for lenses that don't fit well.

I have a lens set that doesn't fit well when taking them out of the case. They are cold. When warmed up, especially in the sun, they fit well. I don't have to use tape or shim rings.

Thanks for your feedback, gentlemen. To be clear, my lenses attach, lock and detach just fine. Not too tight, not too loose. It's just the mount itself that seems to be slightly pliable in its recess, as if the mount itself is buffered by rubber instead of hard steel.

ShaheedMalik wrote:A flaw of the mount. I used electrical tape on my camera to stabilize my lenses.

I've decided to use velcro wire tires to stabilize my lens by wrapping it around the top of the lens and 15 mm rods, keeping it snug against my makeshift lens support post.

I've not had any issues with mine. (Purchased Spring 2020.)

If it's really loose against the case, something is wrong.

Phil999 wrote:shim rings might also help for lenses that don't fit well.

I have a lens set that doesn't fit well when taking them out of the case. They are cold. When warmed up, especially in the sun, they fit well. I don't have to use tape or shim rings.

Where did you get your shim set from?

PL stands for Positive Lock.

MFT is great for its flexibility but one of the flaws of all these stills photo mounts is that they aren’t designed for the precision of cinema usage.

JB

that's the one thing I don't like with M43. It is so unreliable. Yesterday I had a focus motor on a lens (still cold), and there was some play when the motor changed direction. And no time for applying shims.

ShaheedMalik wrote:Where did you get your shim set from?

You can get them from many stores. The ones I have were included in the Laowa 6mm cine lens, and in the Zhong Yi Mitakon Speedmaster set.

“Shim” refers to some foreign object wedged between the lens and camera mount?

Proper lens shims aren’t going to affect the fitment of the lens to the camera.

Good Luck

John Brawley wrote:PL stands for Positive Lock.

MFT is great for its flexibility but one of the flaws of all these stills photo mounts is that they aren’t designed for the precision of cinema usage.

JB

Now, THAT makes sense. We are using cameras not designed for tough industry wear and tear. I am using Rokinon DSX cine lenses that are pretty long and not too light. They lock on just fine but when I use a follow focus without some sort of additional lens anchoring solution (like the Lanparte lens support with rubber strap or a matte box solution that anchors the lens up front to the 15 mm rods via a lens support bracket) the lens will push up or down a fraction of an inch as if the lens mount is pushing the camera mount up and down in the camera housing.

When I use motors, I anchor the front of the lens to the matte box.

Definitely a good idea.
Other than the heavy metal of a big Ursa, those polycarbonate BMPCCs are so light that you can rather hang them onto the lens than the other way around.

HughDiMauro wrote:We are using cameras not designed for tough industry wear and tear.

The problem is more that ever since the Canon MK II Dslr, many people are using still mounts not designed for video or film; designed only to focus on one image at a time, with lightweight small lenses. The two defacto mounts for Broadcast and Film have been B4 and PL respectively; both passive and sturdy locking mounts.

It's not necessarily the robustness of the mount (you can use rails for support) though as the movement and it's effect on back-focus. Not so much with primes but particularly troublesome with zooms, especially those designed to be parfocal. The Canon EF Super35 zooms at least have back focus adjustment; but shims can be quickly made meaningless without some positive lock mechanism.

Uli Plank wrote:Definitely a good idea.
Other than the heavy metal of a big Ursa, those polycarbonate BMPCCs are so light that you can rather hang them onto the lens than the other way around.

I thought that, too!

Steve Fishwick wrote:

HughDiMauro wrote:We are using cameras not designed for tough industry wear and tear.

The problem is more that ever since the Canon MK II Dslr, many people are using still mounts not designed for video or film; designed only to focus on one image at a time, with lightweight small lenses. The two defacto mounts for Broadcast and Film have been B4 and PL respectively; both passive and sturdy locking mounts.

It's not necessarily the robustness of the mount (you can use rails for support) though as the movement and it's effect on back-focus. Not so much with primes but particularly troublesome with zooms, especially those designed to be parfocal. The Canon EF Super35 zooms at least have back focus adjustment; but shims can be quickly made meaningless without some positive lock mechanism.

Thank you! Gonna just make do with what I have until I make the jump to a proper cinema camera.