Full frame

Started Jul 5, 2012 | Discussions thread
HBowman Senior Member • Posts: 1,237
Re: Full frame

rf-design wrote:

HBowman wrote:

Building a FF foveon will be not more complicated than building the actual 1.5 Foveon.

Wrong: Wafer processing of 36mmx24mm is significant more complicated because there is no stepper outside Sony and Canon

Actually, our 1.5 foveon do have very small sensels. Carving very small sensels is costly and a pain in the ass (especially when you do it kinda alone like SIGMA).

Building actual FF like D700 or 5DII is, by far, as difficult as building actual Merrill Foveon because of the 3 layers.

Actually, on hearth at least, the 1.3 APS-H format made by Canon (and some other brands) is the biggest sensor who can be made in 1 ONE "step". All sensors, from tiny pinhole to APS-H are made in only one step, which is why they "should be inexpensive".

For FF, there is more than one step to produce 1 sensor. There is 3 steps, like the 3 layers in the foveon. This is why they are more expensive than APS-C and APS-H (maybe not anymore with the venture of "cheap-eco" sensors sold by Sony to every body who is ok back the pants).

The wafer processing involves about 20-30 mask steps. If the image size of the stepper is smaller than FF you need 2,4,6 and so on steps per mask and stitching them. Not 3 or any odd number. FF is stitched 2 times but there are drawbacks. If you stitch you loose accuracy and resolution. That is because w/o stitching there could be some amount of image distortion, significant more than resolution. But if you stitch you need to align a left hand edge of the first to a right hand edge of the second mask. Because the distortion is not perfect radial but have also have decentering you loose stitching accuracy. That is a secret to optical stepper makers Nikon and Canon. And I think it has less to do with cost than control.

Nikon, Canon and Sony

... And I continue to think that SIGMA have hard time crafting Foveons, which let me think that they will not have "very big" problems to build FF ones.

Foveon is one (if not the most) complicated sensor to craft.

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