Arri Alexa and Mysterium-X...

[jonnycom]

Rodney and Alexa

He says Alexa takes 2 frames to combine them for HDR... thats cool. I wonder if the highlight frame has a faster shutter...

http://vimeo.com/10519628

Does he say Arri makes Optimo's?

[Michael Bravin]

Rodney and Alexa

He says Alexa takes 2 frames to combine them for HDR... thats cool. I wonder if the highlight frame has a faster shutter...

http://vimeo.com/10519628

Does he say Arri makes Optimo's?

Not two frames but dual gain taps off the CMOS we call it Dual Gain Architecture-

The ALEV III sensor design provides 32 pairs of outputs. Each channel is divided into a high gain path (H) and a low gain path (L), resulting in 64 channels arriving at the 14 bit A/D converters. In the final images the lowlights are reconstructed from the high gain path and the highlights are reconstructed from the low gain path for an image containing meaningful information in all 16 bits.

[Martin Stevens]

Not two frames but dual gain taps off the CMOS we call it Dual Gain Architecture-

The ALEV III sensor design provides 32 pairs of outputs. Each channel is divided into a high gain path (H) and a low gain path (L), resulting in 64 channels arriving at the 14 bit A/D converters. In the final images the lowlights are reconstructed from the high gain path and the highlights are reconstructed from the low gain path for an image containing meaningful information in all 16 bits.

Your statement leads me to believe that this dual gain tap is how the Alexa
derives it 13 stops of DR, and not how it achieves HDR. For me, 13 stops
of captured DR per frame is not HDR. So by this standard is there actually
going to be a HDR mode on the Alexa, as in 18 stops etc.?

Perhaps I have misunderstood you???

[JD Holloway]

Your statement leads me to believe that this dual gain tap is how the Alexa
derives it 13 stops of DR, and not how it achieves HDR. For me, 13 stops
of captured DR per frame is not HDR. So by this standard is there actually
going to be a HDR mode on the Alexa, as in 18 stops etc.?

Perhaps I have misunderstood you???

You would hope neither is true I would think.

[David Mullen ASC]

Where did Michael Bravin use the term "HDR" that he should now be accused of misusing it?

[Steven Caesare]

Not two frames but dual gain taps off the CMOS we call it Dual Gain Architecture-

The ALEV III sensor design provides 32 pairs of outputs. Each channel is divided into a high gain path (H) and a low gain path (L), resulting in 64 channels arriving at the 14 bit A/D converters. In the final images the lowlights are reconstructed from the high gain path and the highlights are reconstructed from the low gain path for an image containing meaningful information in all 16 bits.

This description of the latest sensor from Arri has been around for some time.

Is this what you was referred to as HDR on the Alexa? That phrase would seem to be new to the Alexa (and based on Rodney Charter's comment in a video?).

Is it the method used to arrive at the dynamic range the camera is currently touting (~13+ stops), or is it HDR in the accepted sense of generating images that have a greater range than what the camera can normally achieve in a single exposure?

-sc

[Steven Caesare]

Where did Michael Bravin use the term "HDR" that he should now be accused of misusing it?

David, I'm not sure Michael ever did. Rodney Charters described combining two frames, the second one "with highlights in mind", and outputing them. Here: http://reduser.net/forum/showthread.php?t=43257

He didn't use the term HDR, but some body in that thread did, and Michael hasn't corrected the notion.

I'm trying to figure out if Rodney was describing HDR (his phrasing implies some temporal difference between the frames), or if he was just attempting to describe what Michael has posted here (the dual gain channels), albeit not as accurately.

I tend to think it's the latter.

-sc

[Martin Stevens]

Yes, it would be nice if Michael Bravin could chime in here
and clarify the Alexa HDR issue.

[M Most]

Yes, it would be nice if Michael Bravin could chime in here
and clarify the Alexa HDR issue.

He already has. He just gave you a very direct description of how the Alexa is maximizing its available dynamic range. I would suggest re-reading his last post, which is very clear, and not using someone else's slip of the tongue as some sort of accusation.

[Martin Stevens]

I have made no accusation. I was going by his direct response
to an HDR question from another post that he quoted. I was just
asking him to help me understand. There is no
subterfuge in my post.