Re: Digital vs 35mm camera optics

From: Jamie Carter (jacarter3_at_onebox.com)
Date: 08/18/04 

Date: 18 Aug 2004 15:47:05 -0700

True, "#3" was the original thrust of this thread and I was responding
to a more general comparison. However, the is no comprehensive answer
to this question. I can achieve similar performance with respect to
the sensor with "equivalent" requirements, manufacturing processes,
and optical complexity for either sensor. Since the lens is smaller, I
may save money on materials, but this is a meager fraction of the lens
cost.

However, if one considers the constraints imposed by the market for
size, portability, lens to senor spacing, and weight regarding
consumer grade digital cameras, then these factors influence the
design more than apparent resolution. The design must use steeper
(faster) surfaces and many include aspheric surfaces that require
tighter element and mounting tolerance which tend to drive cost if
made with "equivalent" precision. My point, now being clearly stated,
is that the digital camera lens could exhibit more relaxed tolerance
and complexity if the design was based (weighted) on the resolution
issue alone. The additional and real (market based) product
requirements negate and reverse the advantage of "reduced" sensor
resolution. Thus the quality and performance of the "as built" lens
for consumer digital cameras ares generally poorer than the 35mm
camera (scaled to the sensor) in order to minimize cost but this is
transparent to the user.

My experience is based on the design of a high volume lens for a
start-up in Si Valley that was to market the now ubiquitous CMOS
camera. This lens had few elements and was one of the toughest designs
I have yet to undertake. This was contrary to my intuition too.

Jamie

AES/newspost <siegman@stanford.edu> wrote in message news:<siegman-554796.10585618082004@news.stanford.edu>...
> In article <4b78e1a9.0408180641.72e5e96d@posting.google.com>,
> jacarter3@onebox.com (Jamie Carter) wrote:
>
> > This discussion has moved from the optical scientist to the realm of
> > the consumer. I worked at Kodak in the (very) early 80s when the Kodak
> > "disc" camera made its debut. Back then, Kodak still did a great deal
>
> (remainder snipped)
>
>
> Without doubting or quarreling with anything in this or earlier
> messages, could I re-phrase a couple of the questions involved in the
> discussion:
>
> 1) My impression has been that the number of resolvable spots on a
> single frame of reasonable quality 35 mm film is quite a bit larger than
> the total number of individual pixels on the image sensor of a typical
> few-megapixel digital camera. True?
>
> 2) If so, seems this would imply that a 35 mm camera with a good enough
> lens, focused carefully enough, held sufficiently motion-free, and so
> on, could capture a correspondingly larger amount of detail, or have
> correspondingly better resolution, than the typical consumer digital
> sensor with any level of optics. Reasonable deduction?
>
> 3) Taken in reverse, this says that the requirements on the optics that
> are needed to approach the limiting capability of the sensor in a
> digital camera will be less stringent (or easier to achieve?) than those
> needed to approach the limiting capability of a 35 mm film camera. True?
>
> As best I remember the original post, it was question #3 that the OP was
> attempting to ask.

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