The EVIL Camera Design Project update...

Started Oct 30, 2007 | Discussions thread
OP chuxter Forum Pro • Posts: 21,714
Re: I'd buy one ... BUT

AlanF wrote:

3. Unless you're using a rolling electronic shutter you'll need an
anti-shutter to shield the sensor during readout.

Thinking about this some more, I conclude that this is a MAJOR issue! Even if I used a rolling electronic shutter, there is another need for total darkness at the sensor: dark frame subtraction. I conclude that I need to supply a little blinder in the lenses. OK, that fixes the EVIL-specific lenses, but all the legacy dSLR lenses I was hoping to use don't have blinders in the lenses! I'm thinking about adding a blinder in the adapter for these lenses...but it's getting crowded in there...AF motor, processor, and now a shutter. Also, in a lens, it's easy to supply a simple shutter, since the diameter of the light beam is small at the location of the iris and shutter. That makes room for them. In the adapter for these dSLR lenses, the diameter of the light beam is HUGE on some lenses (the back element of my 50mm f/1.4 lens is about 1.4" or 35.6mm). This means that the shutter has to be bigger than that. The OD of the adapter is about 2.3" or 58.4mm, which doesn't make much room for a shutter mechanism AND a focus motor AND a processor. A conventional multi-blade shutter would need about 13 blades and not leave much room to get the AF shaft by it. I'm going to do some layout work on this...

Thanks for showing me this problem!

7. I'm not sure about the Z-axis autofocus!

Did you read everything about it? Do you understand how it's supposed to work?

Here is a simple example...

I setup the subject at 3.0 meters from the camera. I set the camera's focus at 5.0 meters and took a pic. Then I moved the sensor about 0.010" (0.25mm) back and took a pic...this was focused at 3.1 meters. Then I moved the sensor forward about 0.010" from the original position and took a pic. This was focused at 13 meters.

Here are the three pix:

Even at these low resolutions, it should be obvious that it's a trivial task to decide to focus the lens closer to the camera. I believe that a heuristic algorithm can also make a rather good prediction of how far.

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Charlie Davis
Nikon 5700 & Sony R1
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