Archive for the ‘sensor’ Category

Canon C300 – Great Reviews & Posts

Thursday, December 1st, 2011

The Canon C300 is of interest to me as a potential “workhorse” video camera (replacing my current EX3) for both cinematic projects and live events (incidentally, after having written that sentence, I reassuringly found the same phrase uttered by Philip Bloom, so hopefully I’m on the right track here).

Cinematic projects in particular can benefit from more controllable DOF and both can benefit from light sensitivity, while the live events (indoor or outdoor) in particular can benefit from latitude.  Of course these things are handy in general, but those are the occasions when I’ve felt they were lacking in the past.

The C300 addresses most things, apart from lack of 10-bit output.  Hopefully I could trade-up to that in a couple-or-three years’ time when Canon upgrade to that.  And investing in “glass” (lenses) for it is probably a better investment than external recorders (buy or hire) for my current EX3.  The price stings a bit though, so I won’t just leap into it.  I’ll definitely begin by hiring/renting.

My Canon C300 research-in-earnest begins here with a (great) review I initially heard about (via private IOV forum).  That’s the UK’s Institute of videography by the way.  Here:

The following thread at DvInfo includes rolling-shutter-provoking tests (flash, jerk-motion):

The main points about the camera (for me at least, and not in this particular order) are:

  • Ergonomics / practicalities:
    • Better (some say) than the F3.
    • Weatherproof, sensor-cooling
    • ND Filters (three) in-camera
      • Seems fairly unique in this kind of camera
    • Handy proper buttons for Zebra, Peaking, Magnified views.
    • LCD and button-panel orientate in various directions.
    • Fits on a standard DSLR rig.
      • But Zacuto supply a tailored rig.  CVP are among its agents.
      • And there’s Redrock’s inspiringly-named UltraCage.
    • Solid construction, feel and mounting threads, better than “single central bolt” like many cameras have.
    • Wi-fi adaptor transmits a low frame rate version to your computer. If the lens is set to autofocus, you can actually change the focus remotely.
      • Wifi controller is an additional item – not part of the basic package
    • Battery lasts 5 hours
  • Sensor
    • Latitude (recordable, depending on settings):
      • Quoted as “13+ stops in the field”
      • But there is uncertainty over this, since apparently <<Canon thinks that with their Canon-Log color space, the camera allows “800% overexposure… which translates to …an Exposure Latitude of 12 f-stops.” Graeme Nattress of Red disagrees.>>>
    • Less noise, moire and jello than 5D Mk.2 etc.
      • Noise & moire reduction largely result from 4K sensor + DSP to HD.
        • Moire tends to result from significant interpolation inherent in less dense sensors
    • The “less noise” hence less need for low fstops (coupled with smaller sensor than 5D) means greater DOF (the antithesis of the 5D).
      • Greater DOF is preferable at times, for practical as well as aesthetic reasons (when you want to see the background).
  • Lens Mount
    • Camera comes in two lens-mount varieties, not interchangeable:
      • EF-Mount for Canon lenses (ordinaire & “CN-E”).  This is the one for mortals like me.
        • Permits iris to be controlled via dials on camera.
        • Greater available selection of lenses (also usable on stills cameras) e.g.:
          • Telephoto: “EF 70-200mm f/2.8L USM” telephoto zoom lens and tilt-shift lenses.
          • Macro: “EF 100mm f/2.8L Macro IS USM” (article photos include an image of ants)
          • Fisheye: “EF 8-15mm f/4L Fisheye USM”
          • TiltShift: “TS-E 90mm f/2.8”
        • Image Stabilisation (IS) is reported to be good e.g. with the Canon L 70-200mm F2.8 IS Version II
      • PL-Mount: More for movie professionals.
  • Recording:
    • Resolution: HD 1080p & 720p
    • Frame-rates: variable 1 to 30 fps in 1080p mode, and 1 to 60 fps in 720p mode, 1 fps increments.  Also time-lapse and stop-motion/claymation (latter is several frames per “click”).
      • But, like F3 (and unlike FS100), overcranking requires dropping to 720p
    • It can also shoot 50i and 60i (interlaced), useful for deriving 50p and 60p in post.  Historically (e.g. for DV or HDV (Z1) footage), I have done this using freeware (AviSynth and its TDeint filter) for this, but Apple Compressor and other alternatives exist too.  Stu Maschwitz apparently covers this topic in his book << The DV Rebel’s Guide>>
    • Gamma: includes Canon’s Log Gamma.  LCD & V/F display flat and corrected.
    • Audio: uncompressed 16-bit audio at 48 khz (info from FAQ).
  • Recording format:
    • Compact Flash (over 5 hours for a 128GB card)
    • MPEG-2 Long GOP 4:2:2 MXF codec with a constant bit rate of 50 megabits/sec.
      • Philip Bloom says “It is the bare minimum for HD acquisition, but it at least reaches it.”.
      • Sample recording (MXF as stated) is available here (according to here).
      • {Does MPEG-2 imply 8-bit?}
        • Yes.  That is highlighted in several other sites e.g. this and this.  Some believe (rightly or wrongly) that this limitation is a “corporate rather than technical” decision, and a future generation will have 10-bit.
      • {What of the Log Gamma? 8-bit (is it ?) would limit its usefulness or not?}
        • Opinions differ.  Obviously the extent to which it matters depends on the scene.  Some views and image comparisons are here, for 10, 8 and even 7 bits.
          • At that link, one poster suggests dithering as a work-around to reduce banding (from any camera): adjust camera to give noise then (in post) use a good noise-reduction plugin.
      • The only Super-35 sensor camera in its price category (as of fall, 2011) that records 4:2:2 color sampling on-board.
  • Ports:
    • XLR (via clip-on monitor assembly?)
    • Time code, Genlock, HD/SD-SDI and HDMI
      • {But how many bits? 10 (as I’d hope) or still only 8?}
        • Only 8-bits, surprisingly.  It is reported that: “SDI output (is) limited to 8-bit 4:2:2”
  • Monitoring
    • RGB histogram, vectorscope and an Edge monitor (focussing)

More links:

Other Misc. Links:

Full-Frame Sensor Cameras (& Canon 5D vs 7D etc.)

Monday, November 28th, 2011

I have a friend/colleague with a Canon 7D and girlfriend with 500D.  Also I am aware of “Super” (reduced size) “35mm” sensor video cameras.  I’m keeping an eye on all the options, as currently I have no 35mm etc. capability and hence limited shallow DOF and low-light capability.  And to share / compare info with those mentioned people.

Starting with Looking at Philip Bloom’s site to (routine check see what’s new there), I came across these useful links (even though they’re not all new).  I’m attracted to getting a Magic Lantern-ed second-hand 5D Mk.II for creative purposes, especially since my typical work-pattern is not that time-critical and I am reasonably fluent with frame-rate conversion where necessary. I’ll try it out on the 500D first.  The 500D can only do 30 fps at 720p (drops to 20 fps at 1080p) but its sensor is almost an inch across i.e. about double that of my existing EX3.

Incidentally, I previously covered sensor sizes and their names at  and there’s Canon’s take on it at which (oh yes) is about their new C300 camera (will cover that in a separate blog-post).

Here are the links:

    • In a nutshell, 5D has (fairly uniquely) a full “35mm” sensor, giving the ability to achieve correspondingly uniquely shallow depth of field.  But it shoots at a non-standard frame-rate of exactly 30 fps (not 29.97 fps).  This can matter e.g. when intercutting with standard 29.97 material.  On the other hand when using the camera on its own (and I guess with possible allowance for the time duration change and audio pitch change if you fiddle the metadata) it need not matter.
    • Magic Lantern firmware is available for the {original} 5D but not the 7D.
    • Meanwhile the 7D has less shallow DOF capability and slightly more noise but slightly less rolling-shutter effect and, crucially, a number of standard frame-rates.
  • Magic Lantern – unofficial extended firmware for Canon cameras like 5D
    • Magic Lantern gives many improvements to modes, metering displays (e.g. zebra & peaking) and quality (e.g. more shutter-speed choices and greater recording bitrate).  However it does not (yet?) provide additional frame-rates.
      • As of today (2011-11-28) it is reported that Magic Lantern is still not available for the 7D, though progress towards this is being made (slowly).
      • There are limitations to shooting movies on a 5D Mark II, notably the limited 12 minute recording time.
      • (An image illustrates a 5D “tooled-up” with rods, mattebox, audio box etc. to serve as an outside rig)
      • Altering frame-rates is still on the to-do list.  Hence not yet done!
    • FINALLY the full frame Canon 1DX DSLR featuring “improved video”.
    • STandard frame-rates: 24,25, 30p in full HD and 50 and 60p in 720p mode
    • Intra-frame and Inter-frame compression (H264), easing editing.
    • Single clip length of up to maximum of 29 minutes and 59 seconds (reflecting an EU tax rule {on what constitutes a stills – as opposed to video – camera} )
    • will retail body-only for around $7000!
      • {Not as cheap as the 5D Mk.II then…}
  • Canon 500D
      • {Great site, reviewing it and breaking-down the tech-specs.}
      • Thanks to its APS-C sensor size, all lenses effectively have their field of view reduced by 1.6 times.
        • {This is smaller than the 5D’s full-frame but still not bad at almost an inch wide, which I take to be about double that of my EX3’s “Half-Inch” sensor}

Camera Sensor Sizes (Crop Factor, APS-C)

Wednesday, November 9th, 2011

What is a four-thirds sensor?  Is a 35mm sensor measured across the diagonal (like a TV screen) or width etc.?  What is ASPC?

The answers I found are:

    • Sensors are often referred to with a “type” designation using imperial fractions such as 1/1.8″ or 2/3″ which are larger than the actual sensor diameters. The type designation harks back to a set of standard sizes given to TV camera tubes in the 50’s. These sizes were typically 1/2″, 2/3″ etc. The size designation does not define the diagonal of the sensor area but rather the outer diameter of the long glass envelope of the tube.
    • There appears to be no specific mathematical relationship between the diameter of the imaging circle and the sensor size, although it is always roughly two thirds.
      • {The article includes a look-up table for the exact figures}
    • A “35” mm sensor is actually 36 mm on the width;  the height being 24 mm and the diagonal 43 mm.
    • Advanced Photo System type-C (APS-C) is an image sensor format approximately equivalent in size to the Advanced Photo System “classic” size negatives. These negatives were 25.1 × 16.7 mm and had an aspect ratio 3:2.
    • Sensors meeting these approximate dimensions are used in many digital single-lens reflex cameras, in addition to a few large-sensored live-preview digital cameras and a few digital rangefinders.
    • Such sensors exist in many different variants depending on the manufacturer and camera model.  All APS-C variants are considerably smaller than 35 mm standard film which measures 36×24 mm. Sensor sizes range from 20.7×13.8 mm to 28.7×19.1 mm. Each variant results in a slightly different angle of view from lenses at the same focal length and overall a much narrower angle of view compared to 35 mm film.
    • This is why each manufacturer offers a range of lenses designed for its format.
    • Philip includes a diagram comparing sensor sizes.