Blackmagic Forum

Hi!

I was used to shoot with DSLRs before I got the BMCC.
Just wondering about the ASA settings. Which of them gives the most dynamic range?

I'm used to shoot at the lowest ISO to get most DR, but then I read the native ASA for BMCC is 800. Does that mean that both over and under 800 you lose some detail?

Thanks!

Iver

Hi Iverha

My advice is, if you're shooting raw, don't worry about ISO; in raw ISO is more of a display preview attribute than anything else; it doesn't seem* to influence the raw output in any meaningful way. When I shoot with the BMCs (in raw) I set Zebra for 100% and I just make sure nothing meaningful has zebra on it. This is effectively like shooting at 200 ISO... the results are amazing and the DR is out of this world (when you compress the dynamic range the output comes close to HDR).

The manual is a bit confusing because it says the optimum ISO is 800, but I think it says that because if the camera is set to 800 in raw it's a half-way point in the image level (between 200 and 1600) and as such will give you a better idea of what you're capturing.

More confusion originates from the analog gain in most cameras... it's my understanding that the native ISO on most Canon SLRs is 400... therefore 100 is like -6db gain. At negative gains there's a greater likelyhood that highlights in the image will overexpose on the sensor before they reach the Analog/Digital converters, and as such part of your DR is lost (ML ISO). It seems that the BMC doesn't have any analog gain (because the bit depth is large enough to capture the entire sensor's DR) and therefore the issue of ISO restricting DR on the BMC doesn't exist.

Once again, if I'm wrong, please correct me .

*seems because we don't know for sure (?) whether or not the camera applies analog gain based on ISO settings... but if it does it's negligible. The reason I don't know for sure whether or not ISO applies some gain is because zebra on the camera's display changes depending on whether you're on 200, 400/800 or 1600.

Aaron Scheiner wrote:Hi Iverha
.....

I really appreciate your answer, thanks!

I can't seem to notice any big loss changing the ASA myself.
It's not much of noise on any settings either, as long as I expose correctly. But thanks for the tip about zebras, I've been using 70% till now because that's what I'm used to. I noticed it really took a lot of light to get zebras, whatever aperture and light sources I used. So it makes sence what I've read a few places on this forum now, that zebra stripes on the BMCC basically means overexposed.

"been using 70% till now"
As I'm sure you already know, exposing so that the brightest object in frame is just below 100% zebra will produce the best DR, anything else will result in a poorer DR :/ .

There is no analogue gain applied to the sensor (like canon do.)

The cameras native ISO is 800, and to get the most DR you should expose at ISO 800, especially if you use ProRes in camera.

The Zebra is LINEAR and works of the sensor and is independent of the ISO. 70% is not where 70% is compared to your old REC 709 style Zebra. It's much higher. This is OK, because the camera has a very linear response and you can more safely take things up towards near clipping (white) without the colours leaching away like they do with a lot of other cameras.

A lot of people use 100% zebras to show clipping and assume anything that isn't in Zebra will be useable later on.

It's better to be a bit more conservative with your exposure (lower) if you're shooting ProRes.

jb

Thanks for good tips, guys!

Is there specific values that you think would be optimal for prorez?

We will be shooting small spot this week but got me wondering what would be the optimal zebra
level for prorez?

John Brawley wrote:There is no analogue gain applied to the sensor (like canon do.)

The cameras native ISO is 800, and to get the most DR you should expose at ISO 800, especially if you use ProRes in camera.

The Zebra is LINEAR and works of the sensor and is independent of the ISO. 70% is not where 70% is compared to your old REC 709 style Zebra. It's much higher. This is OK, because the camera has a very linear response and you can more safely take things up towards near clipping (white) without the colours leaching away like they do with a lot of other cameras.

A lot of people use 100% zebras to show clipping and assume anything that isn't in Zebra will be useable later on.

It's better to be a bit more conservative with your exposure (lower) if you're shooting ProRes.
jb

John.. first thanks for all you've done sharing information. Super helpful. Curious to know what you're using for ND. I've read many of the posts and I'm getting ready to upgrade from a fader to a ??? not sure yet. A set of 4x5.65's with IR seems like the best choice but very expensive. Maybe a Heliopan with IR on the top like Frank used?

Marshall Harrington wrote:

John Brawley wrote:There is no analogue gain applied to the sensor (like canon do.)

The cameras native ISO is 800, and to get the most DR you should expose at ISO 800, especially if you use ProRes in camera.

The Zebra is LINEAR and works of the sensor and is independent of the ISO. 70% is not where 70% is compared to your old REC 709 style Zebra. It's much higher. This is OK, because the camera has a very linear response and you can more safely take things up towards near clipping (white) without the colours leaching away like they do with a lot of other cameras.

A lot of people use 100% zebras to show clipping and assume anything that isn't in Zebra will be useable later on.

It's better to be a bit more conservative with your exposure (lower) if you're shooting ProRes.
jb

John.. first thanks for all you've done sharing information. Super helpful. Curious to know what you're using for ND. I've read many of the posts and I'm getting ready to upgrade from a fader to a ??? not sure yet. A set of 4x5.65's with IR seems like the best choice but very expensive. Maybe a Heliopan with IR on the top like Frank used?

I agree, John Brawley has really been a asset here, I'm not one who gives credit easily but thank you john for everything, and I even appreciate you correcting me when I'm wrong, now that's a Big pill to swallow

But after seeing much of your work (Admittedly I had not much knowledge of you) recently, I must say I'm a fan now, I'm going off topic but what the hell, "100 Bloody Acres looks amazing!" I freaking love the trailer, and can not wait to see the movie..

Btw, I know that the Sensor is the reason for that great DR but in matter of RAW vs. ProRes - is that 13 Stops DR really only while shooting RAW or does it happen to be there to while shooting in ProRes Film?

maxemanuel wrote:Btw, I know that the Sensor is the reason for that great DR but in matter of RAW vs. ProRes - is that 13 Stops DR really only while shooting RAW or does it happen to be there to while shooting in ProRes Film?

John Brawley and others say the BMCC records "about 1 stop less" DR in ProRes HQ Film mode compared to RAW CinemaDNG mode. I suspect DNxHD Film & ProResHQ Film are similar in this regard.

I don't have a camera yet to confirm this, but I trust the above is correct.

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Peter, it's a real pitty you don't have a camera, you provide some really good advice/insight which I'm sure would be enhanced if you had a BMC to experiment with. Thanks

If i'm not mistaken then 444 prorez?

If so then yes you get some more out of the file.

Aaron Scheiner wrote:Peter, it's a real pitty you don't have a camera, you provide some really good advice/insight which I'm sure would be enhanced if you had a BMC to experiment with. Thanks

Thanks very much, Aaron.

Just to be clear: I was actually finally offered to buy a BMCC-EF (which I pre-ordered in April 2012) about a 2 months ago, but instead I changed my pre-order twice: Once to a BMCC-MFT, and then again after the new camera announcements at NAB 2013, I changed my pre-order to a new BMPC-4K camera.

If the BMPC-4K is late shipping (I'll wait until about late Aug. 2013 or so), I'll get a BMCC-MFT instead, if one is available, or, if not, a non-BMD camera!

Margus Voll wrote:If i'm not mistaken then 444 prorez?
If so then yes you get some more out of the file.

I'm not sure what you're referring to here?

The version of ProRes recorded by the BMCC is "ProRes 422 HQ", which is 1080p, 10-bit, 4:2:2 @ up to 220 megabits/sec.

"ProRes 4444" is different. See the ProRes White Paper available for download here:
http://www.apple.com/finalcutpro/resources/

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Dear God is there a post that Peter J. DeCrescenzo has not weighed in on?
Please point me to one single post Just one post, For crying out loud there must be one!

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Every single post you have made seems robotic, yet Human

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Darryl Gregory wrote:Dear God is there a post that Peter J. DeCrescenzo has not weighed in on?
Please point me to one single post Just one post, For crying out loud there must be one!

Haha Peter J. DeCrescenzo, you are a Spammer but we love you cause your a nice guy
Every single post you have made seems robotic, yet Human

Keep up the good work, I'm not sure how your Ipad does all the work, But Over Heating is not a problem

My secret is: No alcohol, drugs, coffee, or fast women.

I'm saving all that for my retirement, which I assure you will be very, very brief -- if it ever happens at all. Cheers.

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