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Author Topic: Autofocus with RED cameras and lenses  (Read 10018 times)
BJL
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« on: November 18, 2008, 01:22:12 PM »
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What specifics are known of the autofocus capabilities for RED cameras, both with RED lenses and when using other lenses (Canon, Nikon) through adaptors?
The prospects for using these as high frame rate still cameras for fast action might be greatly affected by the answer.

Also, do RED cameras use progressive scan (with the resulting wobbly effects with certain combinations of camera and subject motion), or do they detect all pixels of a frame simultaneously?
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Graeme Nattress
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« Reply #1 on: November 18, 2008, 02:52:43 PM »
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I think you're confusing progressive (as compared to interlaced) with rolling (as compared to global) shutter. The RED cameras are progressive, not interlaced and use a very fast rolling shutter. The faster the rolling shutter, the more it approximates the rolling shutter effect of the spinning mirror shutter in a film movie camera.

Graeme
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Daniel Browning
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« Reply #2 on: November 18, 2008, 02:56:50 PM »
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Quote from: BJL
What specifics are known of the autofocus capabilities for RED cameras, both with RED lenses and when using other lenses (Canon, Nikon) through adaptors?

No specifics are known yet. The current RED ONE camera has no autofocus capability at all. The announced specs include new FF35 RED-mount lenses with autofocus (and stabilized) functionality, which indicates that the FF35 cameras will autofocus with those lenses, at least. At this early stage, RED has specifically declined to comment on whether the Canon and Nikon mounts will include autofocus capability.

Quote from: BJL
Also, do RED cameras use progressive scan (with the resulting wobbly effects with certain combinations of camera and subject motion), or do they detect all pixels of a frame simultaneously?

Most people use the term "rolling shutter" in favor of "progressive scan" (which has other meanings). Not all rolling shutters are the same. The speed of the rolling shutter is measured by the read-reset time. Some are very slow, which makes wobble very obvious, such as in the D90. Others are medium speed, such as the HV30 and EX1, where many people do not notice skew, but others do. Then there are other cameras where the read-reset is very fast, such as the RED ONE, so that skew is not a problem except in certain circumstances such as with strobe lights. After that, there is film-like skew. This is very fast, but the skew is still there and can cause problems. After that there "global shutter", where there is absolutely no skew at all. Some cameras do this now (Vision Research, but not the cine Phantoms), but it changes the look of the moving image in a way that is not pleasing: so film-like read-reset speed is most highly desired. RED has announced that their read-reset will be better in all the new cameras, but only the Monstro-based ones will match film in this regard.

Kind regards,
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Daniel
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--Daniel
RobertJ
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« Reply #3 on: November 18, 2008, 10:20:56 PM »
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I have no need for AF, but we need to at least be able to electronically control the aperture for Canon EF lenses and the newer Nikon G lenses that have electronic apertures and no aperture rings.
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BJL
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« Reply #4 on: November 19, 2008, 02:27:04 PM »
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Quote from: Graeme Nattress
I think you're confusing progressive (as compared to interlaced) with rolling (as compared to global) shutter. The RED cameras are progressive, not interlaced and use a very fast rolling shutter.
Thanks Graeme,
    yes I did intend to ask whether the exposure is "one line at a time" (rolling) or "all at once". I suppose that rolling is not a lot different than what happens with a focal plane shutter at shutter speeds far higher than the flash sync speed, as far as freezing motion goes.

Can you give me details, like
1. the total time between start of exposure at the top line of a frame to ending exposure at the bottom. Is this basically the stated maximum frame rate, or can it he significantly higher?
2.  the minimum possible exposure time at an individual pixel between reset and read-out (or some related measure of the ability to minimize motion blur.)
I am more curious about the use of RED cameras in "freeze-frame" mode than in their moving picture capabilities, which I am sure are excellent.

Also, what can you tell us about
3. AF using RED lenses
4. AF using Canon and Nikon mount lenses.
5. aperture control from the camera body when using Canon and Nikon mount lenses, as  T-1000 mentioned.
« Last Edit: November 19, 2008, 02:28:10 PM by BJL » Logged
Daniel Browning
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« Reply #5 on: November 20, 2008, 04:00:41 AM »
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Quote from: BJL
3. AF using RED lenses

Yesterday RED said "Our auto-focus system will compete heads up with the very best DSLRs." and added that they have Ultrasonic Motors and the stabilization is optical.
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BJL
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« Reply #6 on: November 24, 2008, 10:26:06 AM »
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Quote from: Daniel Browning
Yesterday RED said "Our auto-focus system will compete heads up with the very best DSLRs." and added that they have Ultrasonic Motors and the stabilization is optical.
Thanks for that link to Jim Jannard's comments: RED lenses having AF, USM and stabilization is good news of course.

Jannard's claim that RED's AF system (presumably contract detection) "will compete heads up with the very best DSLRs" is quite ambitious, given the inherent advantages of phase detection AF. I am happy to be hopeful that technological progress can at least reduce the AF performance gap to the point that CDAF and LiveView on LCDs or EVFs can meet the needs of most photographers. I am glad that companies like RED and Panasonic (with micro FourThirds) are working on this in their assaults on the established SLR makers, with Samsung to join with an EVIL system in 2010, and hope that the major SLR makers will be pushed to respond by either adding EVIL options or greatly improving the LiveView AF and video capabilities of their DSLR's.
« Last Edit: November 24, 2008, 10:29:17 AM by BJL » Logged
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