• Nerdacles (Nerd Articles)

    Posted on March 18, 2012 by in Tech Rant

    Major Nerd e-mail if nerdacles

    Evan Kimball to Andrew

    show details 12:22 AM (2 hours ago)

    http://www.bmupix.com/display/ShowImage?imageUrl=/storage/post-images/GH2_sensor_aspect_ratios_1920_1.jpg?__SQUARESPACE_CACHEVERSION=1287002123798
    Comparison of GH2 special sensor, shows how wide angle is utilized and 4:3 aspect ratio, no comparison to APS-C, but this is most accurate representation of use of imaging circle I could find.

    Now here is a chart that shows all common sensor sizes.  It puts things in perspective because 4/3 is 75% of super 35, FS-100 is not using a real super 35mm size but close, and 5D is huge compared to traditional Hollywood standard.  The reason super 35 was invented was anamorphic squeeze works better and it is easier to pull focus on. But damn them they forgot super 16 which is still popular with a lot of independent films http://blog.abelcine.com/wp-content/uploads/2010/08/35mm-digital-sensors-chart_final_1200.jpg

    To go back in time here is a blog on reason why smaller chips were traditionally used for video work.  There are good arguments here and moire is a huge issue on Red because of the larger sensor.  That is why the Red One used a smaller than 35mm sensor.  The Raw codec cleans up the moire really well though.  http://ninofilm.net/blog/2010/04/17/536/

    Not that I’m a total fan boy, but there is a huge bandwagon out there of ppl wanting Full Frame everything and shallow depth of field.  Here is a post of lens diffraction and f-stop sweet spot.  Because the image circle and flange depth on 4/3, it allows lighter lenses with faster f-stops.  So, a lens of 25mm at f/1 is equal to full frame lens of 500 f/2- so they come out about the same in terms of depth of field.  Except for the fact the 4/3 lens lets in twice as much light, giving it an advantage- except the full frame sensor can go higher iso and match that f-stop- so again, they equal out.  FF will have better detail is shadows, in all it wins for low light.  But a fast f-stop will save you compared to slow lens when you need it.  So 4/3 has an advantage in anything using available light, like docs.  Another factor with the smaller sensor is that curvature of field, the curve of the glass elements, comes in latter on.  On a full frame, the whole image circle is being used and sometimes to get a high f-stop we see diameters of 72mm.  A 4/3 lens can do the same thing with half the size.  But if you use a large diameter element on a 4/3 camera only the center of the imaging circle is used and the curvature of field disappears.  What curvature of field does is make soft borders and a sharp center.  If this is eliminated (but whoa it is telephoto now) you have much closer modular transfer function, or sharpness from center to corner- making it ideal for landscapes. There are still more factors though, it is harder for a 4/3 lens with a large pixel density to be equally resolved by a lens.  You need 2,000 lpm to be descently sharp, but most lenses get there easily.  Another consideration is that no ff sensor has the same resolving power as 4/3 because of limitation on pixels.  Right now ff sensors are 24mp, which is somewhat equivalent (in a simplified and somewhat wrong way) to a 4/3 sensor of 12mp, and APSC of 16.  So actually APSC and 4/3 can resolve more detail that any full frame, but it might not look as nice.  This is all theory, but it comes in helpful when choosing how to light and shoot a film no matter what camera you are using.  http://forum.photozone.de/index.php?/topic/1799-fstop-sweet-spot-and-mft/  here’s the link.  It shows that lower f-stops are sharper than higher ones on smaller sensors, so on a 1/3 inch sensor f/2 is the sharpest possible.  But the detail in low light is crappy and noisy.  So it is a big tug of war between what format does what best and how to manipulate them to their fullest potential.  In photography, again, it is more complicated.  You can print a 1:1.65 sensor up to 8×10 before noticing detail issues, a 4/3 up to a pick up truck size, a ff up to a house, and medium format is for billboards.  And HD is only 2mps for 30 foot projection, so you only use 1/8th of the sensor, lol.  That’s why it will be easily to move to 4K, it might even be easier on the camera.  But from what I’m hearing, APSC sensors don’t have enough vertical heighth to easily pull it off.  I don’t understand this though, it is just a blog thing I read but it entails issues canon had with 2k earlier that I have read about before.  Not really important honestly, if the video looks good- who cares how they faked the resolution.

    Anamorphic is awesome, it puts a more cinema feel to things and Zeiss just put out a set of anamorphic digital lenses (meaning they use ed, ud glass).  Rent only, but with a budget it would be possible to use them.  I love Anamorphic and I’ve been wanting to pick up so old Lomo lenses for it, but they are 2 grand, so not affordable right now.  http://www.eoshd.com/anamorphic-guide

    Here is an informal forum discussing issues with sensors and anamorphic.  Interesting but not of high importance.  A DP working freelance might want to know this/  http://www.cinematography.com/index.php?showtopic=50699

    Good post on depth of field and circle of confusion.  Really a text book should be used to understand this if you don’t already.  DOF is interesting because it is completely based on print sizes and a lot of simplified language gets used to explain it online.  Really important for photographers, not film makers who work in same acquisition size.  But it comes into play with HD 2K or 4K and viewing distances; not directly, just in a food for thought way.  http://photo.net/medium-format-photography-forum/000Bne?start=0

    These are just a few of the things I remember talking about and felt I couldn’t explain well enough.  Also don’t be fooled by poorly explained ISO arguments.  DPreview is the most awful site at times and 50% of their forum is dangerous trash.  Native ISO plays a significant role in image and noise and dynamic range and understanding your cameras setting and doing simple tests really assures the best results.  As you can see I’m big into just pushing and knowing a camera system through and through, I hate getting bad footage and not knowing why.

    I was just looking back at my camera though all the options.  I have my high knee setting much higher than I thought.  I must have just plainly thought wrong last night.  Tell me what you decide with the FS100, if I indeed shoot on it I would love to know more about it.

     

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