Fuji X30 wants

Started May 13, 2013 | Discussions thread
Pan Jurek Mr Jerry
New MemberPosts: 9
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Re: Fuji X30 wants
In reply to prime, Jul 11, 2013

Thanks for the reply.                I thought that electronics played a larger role in lens and aperture design.

I remember from my old SLR, no not DSLR but SLR, that I could see the aperture getting bigger and smaller when I played around with the lens once I got it off of the camera.  I cannot see the aperture change on my APS-C sized lenses since I thought that this was done electronically.

prime wrote:

Pan Jurek Mr Jerry wrote:

What I would like to see is the following:

1.) A bigger sensor.

Sure. How much bigger do you want the camera to be to accommodate that bigger sensor? If you swapped a larger sensor straight into the X20 body, the image circle of the existing lens either would not cover the entire surface of the sensor, or there would be serious vignetting. So you necessarily would have to make the lens bigger, too.

5.) A longer zoom. More wider and more tele. (20 - 140)

The current X20 goes to 112 mm equivalent, which is 28.4 mm actual, with the 2/3" sensor. Even with the same size sensor, 140 mm equivalent would require an actual focal length of 35.5 mm. Increase the sensor size to, say 1", and the actual focal length for 140 mm equivalent goes to about 51.7 mm.

6.) A faster lens with a constant appature of F/1.4

In the X20, the diameter of the aperture for f/2.8 at 28.4 mm actual focal length (112 mm equivalent) is 28.4 ÷ 2.8 = about 10 mm; for an actual focal length of 35.5 mm (140 mm equivalent), an f/2.8 aperture requires an actual aperture of about 12.7 mm -- that's still with a 2/3" sensor. Now increase the sensor size to 1" and the actual aperture for f/2.8 at 140 mm equivalent becomes about 18.5 mm. Now increase the maximum aperture to f/1.4, and the actual aperture must be about 37 mm at 140 mm equivalent.

So your specification has increased the actual aperture -- the hole in the lens through which the light passes -- almost fourfold, from 10 mm to 37 mm. How are you going to fit an opening of that size inside a lens barrel the size of the X20's lens barrel? O.k., let's increase the size of the lens barrel. Oops, the lens barrel now overlaps the viewfinder, so we'll have to widen the camera body to move the viewfinder out further, probably have to make the camera a bit taller, too, for the same reason.

But it's not only the aperture that you have increased in size; you have had to increase the size of each of the lens elements inside the lens barrel, too, and those lens elements have mass. If you still want auto focus, you will have to increase the size of the motor moving those lens elements around, which will drain the battery faster, so you will have to increase the size of the battery, too.

There are real physical reasons for large sensor cameras with long lens reach and bright apertures being big and heavy.

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