Thread: Sigma fp

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    #71
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    Quote Originally Posted by Teddy_Dem View Post
    Cinema5D have done a review of the camera (on beta firmware) and put up some sample footage. They are saying 11.3 stops of dynamic range (remember the camera currently has no log profile) and 20.3 ms of rolling shutter.
    Yep it's a DSLR/Mirrorless. 20.3 ms of rolling shutter is just too much.
    Single largest give away for budget cams.


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    #72
    Senior Member Teddy_Dem's Avatar
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    Quote Originally Posted by Samuel H View Post
    ^ Sure. But with 12-bit linear ADCs, you can't get more than 12 stops of DR anyway*, so if they implement a log curve my guess is that they'd use it to reduce file sizes, by switching to 10-bit.
    (* well, you can get more than 12 stops if you measure at reduced resolution, and it's usually the case if your source has much higher resolution than your delivery format; but changing the curves won't help much there either)

    You're completely right that for storing 4k RAW out of 6k images they must be doing some weird voodoo. I'm also very curious about that.
    If you looks the comments of the Sigma fp review post on Cinema5D, there is a discussion about this and they posted a dropbox link to two DNGs (one 8-bit and the other 12-bit) and user Paul Curtis looked into the DNGs with "Raw Digger" and concluded that the 8 bit DNGs are non linear, while the 12-bit files are linear.

    The Sigma fp DNGs:

    https://www.dropbox.com/sh/kq77j8m12...NMxi4fNUa?dl=0


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    #73
    Director of Photography TimurCivan's Avatar
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    Quote Originally Posted by DLD View Post
    Sigma is a part of the L-Mount Alliance and scheduled to release most of its Art primes in L-mount this year already. Meanwhile Panasonic has several zooms out. Supposedly, both of them will work like the native glass.

    Supposedly.
    It does. I have an S1H and shoot Sigma L glass. Works like a charm.

    I tested the fp. It has SO much potential. Just needs a bit of firmware debugging before release. With Sigma L lenses like the 35mm F1.2 its snappy and quick. The 45mm F2.8 is a little gem. love that thing.....
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    #74
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    Quote Originally Posted by Samuel H View Post
    Just the fact that they got in contact with Timur Civan for that promo tells me that they're serious about video. (Timur used to be very active here at dvxuser but hasn't posted in months)
    I'm here im just busy.
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    #75
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    Cinema5D is about spot on.

    There are some issues we hope are getting resolved.

    That said, its an AMAZING directors finder... Takes beautiful stills... and its video capabilities are quite good. They just need to iron out a few things. IF not with firmware, then the MKii version of the fp. This is really their first "video" camera. I'm buying one just becuase i want a small point and shoot with interchangeable FF lenses, and as a directors finder. The Video functions are icing on the cake.
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    #76
    Senior Member Samuel H's Avatar
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    Thanks for the comments. Did you talk to them about the firmware updates? Any sense of whether they'll fix the minor but important things? Any chance they'll get 12-bit cDNG working internally? How do they get 4k raw out of a 6k sensor?

    ("I'm just busy" --> OK here you have a lengthy questionnaire - sorry XDDDD - feel free to ignore, you already did plenty)


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    #77
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    Quote Originally Posted by TimurCivan View Post
    That said, its an AMAZING directors finder... Takes beautiful stills... and its video capabilities are quite good.
    That's pretty much what I was hoping for, since my A7r died on me (I've used it a LOT) and I need a stills camera for photography. Having solid video capabilities will be very useful. Too bad I can't have it in time for the shoot I have tomorrow...

    They just need to iron out a few things. IF not with firmware, then the MKii version of the fp. This is really their first "video" camera. I'm buying one just becuase i want a small point and shoot with interchangeable FF lenses, and as a directors finder. The Video functions are icing on the cake.
    I do hope Sigma follows the Fuji and BMD example and keep updating the camera until it hits its limit. I also hope that the upcoming 135 format Foveon camera is similar to the fp, that would make for a great combination for travel photography and video if so.


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    #78
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    Quote Originally Posted by Samuel H View Post
    Thanks for the comments. Did you talk to them about the firmware updates? Any sense of whether they'll fix the minor but important things? Any chance they'll get 12-bit cDNG working internally? How do they get 4k raw out of a 6k sensor?
    I suspect that the former is unlikely, though I agree that it would be pretty nice.

    Since it requires only an external SSD to record 12-bit cDNG though, I think it's a pretty minor tradeoff.


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    #79
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    Quote Originally Posted by Samuel H View Post
    Thanks for the comments. Did you talk to them about the firmware updates? Any sense of whether they'll fix the minor but important things? Any chance they'll get 12-bit cDNG working internally?
    The Sigma fp can record 12-bit Cinema DNG internally to an SD card in 1080p. The reason it can't do the same in 4K is mostly due to SD card write speed limitations. The bitrate for 4K @ 24fps in uncompressed 12-bit RAW is 2400 Mbps (300 MB/s). For 4K @ 30fps in 10-bit RAW it's 2500 Mbps (312.5 MB/s).

    The fastest UHS-II SD cards are only capable of write speeds of about 200 to 250 MB/s which isn't fast enough for the 4K RAW formats. And given that the bus speed limit of UHS-II is 312 MB/s, it is unlikely we will ever see UHS-II SD cards with sustained write speeds of 300 MB/s+ (since there's usually at least a little bus overhead, actual write speeds rarely reach the theoretical limit).

    So recording internal uncompressed 12-bit 4K RAW would require a faster media format, like XQD, CFast 2.0, or CFexpress.

    Incidentally, it's possible that media speed limitations may be part of the reason why the camera records 4K full frame raw, rather than 6K full frame raw. 6K @ 24fps 12-bit RAW in a 16:9 aspect ratio (in something like the 5888x3312 resolution of the S1H) would require a sustained write speed of 670 MB/s. But the current crop of off-the-shelf USB-C external SSDs like the Samsung T5 seem to be SATA based with maximum write speeds of 500 MB/s or so. Samsung does have the NVMe based X5 external SSD that is considerably faster, but it has a Thunderbolt 3 interface. The camera specifications actually list the USB-C port as USB 3.1 Gen 1 which has a bus speed of 5 Gbps (625 MB/s), so there's not much hope for significantly faster drive options for USB-C recording either.

    I suppose Sigma could consider adding a compressed RAW format to the camera, but then they risk running afoul of the RED patents. Technically, I think the RED patents only apply to lossy compressed RAW, so perhaps they could add a lossless compressed RAW format. The DNG specification does include a lossless JPEG-based compression option with a typical compression ratio of about 1.5:1 (approximately, it varies based on the content). Despite the modest compression ratio, this would be actually enough to put the 4K RAW formats within range of UHS-II card write speeds.

    It's possible Sigma would want to play it safe and stay away from any kind of internal compressed raw though. Blackmagic's cameras had lossless compressed Cinema DNG as an option along with a few lossy compressed DNG formats, but they eliminated all of them when switching to Blackmagic RAW (citing patent considerations as one of the reasons for dropping the old formats).


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    #80
    Senior Member Samuel H's Avatar
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    Oh I see... Thanks.

    Now I need an explanation of how they get 4k raw out of a 6k sensor without cropping, and, even better, an overexposure-underexposure test to see how good the DR is, compared with the p6k (just checked the LensProToGo youtube channel but it's not there... yet...)


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