PCC 6k + Sigma 18-35mm F1.8 DC HSM: Camera can go to F1.7?

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aBavarian Normie-Pleb

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PCC 6k + Sigma 18-35mm F1.8 DC HSM: Camera can go to F1.7?

PostWed Jul 27, 2022 4:26 am

Hello everyone,

I hope I'm not asking an ignorant question, this is on one hand my very first Blackmagic camera and on the other hand my first Sigma lense.

I'm using a Pocket Cinema Camera 6k with the popular Sigma 18-35mm F1.8 DC HSM lense, image quality-wise I'm pretty happy but I noticed something (to me) weird in the camera settings:

The camera's firmware control for the lense goes to F1.7 and not just F1.8.

Is this...

- Normal?
- A bug?
- A hint that something might be broken?

What I've tried without any effect:

- Updated camera to latest firmware with camera software package 7.9
- Reset camera firmware to factory defaults
- Checked that the lense has the latest firmware (2.03) with the Sigma USB Dock
- Reset the lense firmware to factory defaults

Thanks for you guys' help!

Regards,
aBavarian Normie-Pleb
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aBavarian Normie-Pleb

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Re: PCC 6k + Sigma 18-35mm F1.8 DC HSM: Camera can go to F1.

PostWed Aug 03, 2022 7:38 pm

A small update: No changes of the situation with 7.9.1.

But I've heard from other Blackmagic camera users that they've also seen this with the Sigma 18-35 Art lense.
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Uli Plank

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Re: PCC 6k + Sigma 18-35mm F1.8 DC HSM: Camera can go to F1.

PostFri Aug 05, 2022 7:12 am

Nothing broken. Communication error, I suppose.
The software may be free, but the hardware needed for smooth performance is not.

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rick.lang

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Re: PCC 6k + Sigma 18-35mm F1.8 DC HSM: Camera can go to F1.

PostFri Aug 05, 2022 4:05 pm

In a post from BMD, we were told that BMD is reporting the aperture sent by a lens whereas other camera manufacturers may round the value to the lens manufacturers’ published specs.
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Howard Roll

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Re: PCC 6k + Sigma 18-35mm F1.8 DC HSM: Camera can go to F1.

PostFri Aug 05, 2022 10:02 pm

rick.lang wrote:In a post from BMD, we were told that BMD is reporting the aperture sent by a lens whereas other camera manufacturers may round the value to the lens manufacturers’ published specs.


I’m not so sure. The situation with broadcast lenses isn’t any better.

viewtopic.php?f=4&t=165391

Good Luck
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Mike Potton

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Re: PCC 6k + Sigma 18-35mm F1.8 DC HSM: Camera can go to F1.

PostSat Aug 06, 2022 3:28 am

It just doesn’t matter if there is a .1 rounding difference.
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Re: PCC 6k + Sigma 18-35mm F1.8 DC HSM: Camera can go to F1.

PostSun Aug 07, 2022 12:58 pm

The same with pocket4k and metabone, on ursa g1, on 6k, on Sony with adapter sacked falcon lite, on x-t4 with fringer adapter.
May be sigma that send it.
All work fine what is a matter? :-)


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rick.lang

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Re: PCC 6k + Sigma 18-35mm F1.8 DC HSM: Camera can go to F1.

PostSun Aug 07, 2022 1:42 pm

Howard Roll wrote:
rick.lang wrote:In a post from BMD, we were told that BMD is reporting the aperture sent by a lens...


I’m not so sure. The situation with broadcast lenses isn’t any better.

viewtopic.php?f=4&t=165391


Thanks, Howard. I suspect failing to close the iris completely may be a different and more serious issue. My manual Fujinon Cine Zoom iris will close completely.
Rick Lang
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Uli Plank

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Re: PCC 6k + Sigma 18-35mm F1.8 DC HSM: Camera can go to F1.

PostSun Aug 07, 2022 1:46 pm

Most lenses don't close completely, it's normally a feature of broadcast lenses.
The software may be free, but the hardware needed for smooth performance is not.

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