Blackmagic Forum

Not positive this will work for all the non-working EF lenses, but we have discovered a workaround for our particular lens.

We use the Canon EF 24-70mm f/2.8L II USM Zoom Lens.

Our lens was not working.

We purchased the Bescor BM-EPIC Battery & Charger for the Blackmagic Camera.

We discovered when the battery pack was in use, we had IRIS control! Also found that as long as we have external power to the camera that the IRIS worked just fine as well.

So thought we would pass this along for anyone else in the community that may be as frustrated as we were at not being able to use our best glass for things, and hope it works for other lenses as well.

If you have a different lens, and this fix works for you, reply with your lens, and I will start adding confirmed lenses that this workaround works for!

hi can you tell how many hours does that battery last in full charge? and compare to swiftronix PB70, which is better?

Fallsmedia wrote:... We discovered when the battery pack was in use, we had IRIS control! Also found that as long as we have external power to the camera that the IRIS worked just fine as well. ...

That's very interesting. I'm curious if, when the external power source is disconnected, can your camera control that lens' aperture when the camera is in record mode?

For example, the BMCC only enables lens IS during record mode, so I'm curious if a similar thing can happen with aperture control with that particular lens (when external power is not connected).

I just tried it with a Canon 17-40mm F4 L lens and still no control. I even tried while recording.. still no control.

CptZero wrote:hi can you tell how many hours does that battery last in full charge? and compare to swiftronix PB70, which is better?

Have shot for over 4 hours in one sitting so far and Camera still read 100%.

Peter J. DeCrescenzo wrote:That's very interesting. I'm curious if, when the external power source is disconnected, can your camera control that lens' aperture when the camera is in record mode?

For example, the BMCC only enables lens IS during record mode, so I'm curious if a similar thing can happen with aperture control with that particular lens (when external power is not connected).

Yes, we have been able to control the lens the entire time, as long as the battery pack is connected, or AC power is provided. When we remove the external power, we lose our IRIS control also.

Bill Rich wrote:I just tried it with a Canon 17-40mm F4 L lens and still no control. I even tried while recording.. still no control.

Disappointing to hear that, was really hoping that this would work for other lenses, looking at a couple, but they are currently on the Non-op list.

I have the 24-70 2.8L (not II) and it does not work even when plugged in to an external power supply.

Fallsmedia wrote:Not positive this will work for all the non-working EF lenses, but we have discovered a workaround for our particular lens.

We use the Canon EF 24-70mm f/2.8L II USM Zoom Lens.

Our lens was not working.

We purchased the Bescor BM-EPIC Battery & Charger for the Blackmagic Camera.

We discovered when the battery pack was in use, we had IRIS...

Maybe it was putting out 16.8V at that time even though it says normally it outputs 14.8V? By the way the battery is 98 watt-hours. Doesn't that exceed the limit for lithium ion batteries in international flights? Of course not a drawback if you don't travel with it.

Rick Lang
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