Re: Image sharpness and focus distance.

[Bill Glickman <bglick@xxxxxxxx>]

Bob, great points, well said!  


> Take two individuals looking at the same image from a
> Roundshot 24/35. One person will look at objects 20
> feet from the camera and proclam the image sharp as a
> tack. The other individual will look at objects on the
> horizon and say that it is not as good as what they
> would expect from their conventional 35mm camera. Both
> are right!
> 
> The question of sharpness for a revolving camera is
> not as simple as what lens it uses. There is an other
> factor to it. No fixed focus revolving camera can be
> sharp at all distances. For any lens, when focused at
> the horizon the image is a diferent size as it is when
> focused at close distance. Most fixed focused
> revolving cameras are pre set at the factory to be
> focused AND to use that correct amount of film for
> objects at about 20 feet or so. Objects in the close
> forground and at the horizon will not only be out of
> focus because of lack of depth of field but ALSO
> because they are the wrong size for the amount of film
> used. Even if you could set the lens a f/200 objects
> in the forground and horizon can not be sharp because
> they are the wrong size for the amount of film being
> used. Adding a close up filter to a Roundshot 24/35
> may improve the sharpness of an object close to the
> lens, but it is physically impossiable to make it tack
> sharp because the wrong amount of film is being used
> for the size of the image.
> 
> My circa 1905 Cirkut camera has gears to change the
> amount if film used to match where the camera is
> focused. The Super Roundshot has a computer to change
> the amount of film pulled for where the lens is
> focused. For my LarScan homebuilts I prefered to use
> zoom lenses. I would shoot test rolls and mark on the
> barrel where to set the zoom for different focus
> distances and set the zoom for matching image size.
> 
> Bob
> 
> 
> =====
> Robert Erickson, cirkut8@xxxxxxxxx
> The Panoramic Network: http://www.panoramic.net
> 
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