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Re: [OM] Camedia E-10 was Why Olympus...

Subject: Re: [OM] Camedia E-10 was Why Olympus...
From: drchrisbarrett <drchrisbarrett@xxxxxxxxxxxxxxxxxxxx>
Date: Sun, 25 Mar 2001 18:30:48 +0100
Dear C.H.,

I think Einstein said that explanations should be as simple as possible, but no
simpler. I think they have over-simplified here.

Chris

"C.H.Ling" wrote:

> ----- Original Message -----
> From: "drchrisbarrett" <drchrisbarrett@xxxxxxxxxxxxxxxxxxxx>
>
> >
> > In the mean time I've got some physicists disagreements with their
> > statements. I'm bearing in mind here that this is written by advertising
> > people, not necessarily people who would question the science. No
> > offence meant to yourself if you happen to be in advertising!!
> >
>
> No problem, may be they are written by advertising people, but if without
> the technical support from Olympus technical section, they can't do that.
>
> > In 1) they say the film is flat so it can capture light from a variety
> > of angles. This is not strictly true since at very shallow angles the
> > light will reflect off even a film surface. More importantly the diagram
> <snip>
>
> May be, but it may not as serious as CCD, so no one take care.
>
> >
> > Now in 2) they show parallel rays coming out of the whole of the rear
> > element. Well this is also not accurate and is misleading. Yes I can
> > .....
> > What they should really be drawing is a set of rays coming from all
> > parts of the rear element, and meeting at one of the pixels. This is the
> > basis for the calculations I made. The angles I quote are the most
> > oblique rays the lens will produce and will will meet the CCD at its
> > furthest corner.
> >
>
> You are arguing on a carton illustration? that is just a simple illustration
> for normal people, of course they will not write it too detail. You expect
> them to make it in proportion and give you detail dimension, exact light ray
> drawing?
>
> > Having seen it the page I can also find other arguments to disagree with
> > (sorry but I'm just that kind of a guy     8^)      ). They talk about
> > the dust problem leading them to a fixed lens solution (i.e. one sealed
> > against the dust. Yes I can see it could be a problem, but I'm sure a
> > thin multicoated window in front of the CCD would easily solve it.
> >
>
> No problem again, I'm also a guy like to argue, I'm sure you are right and I
> also through this before, but no one is make that and it do cause problem on
> the existing SLR DC. My friend has a S1-Pro he always carry a can of
> compress air with it, he found the dust a very annoying problem.
>
> > Then they talk about needing to fix the lens because an interchangeable
> > lens would flex too much. I find this hard to believe. I don't think the
> > olympus mount 'flexes' much during even a relatively long exposure.
> >
>
> I'm not sure, but what I know is the mirror and aperture stop down mechanism
> that already know to cause very serious problem on image resolution. To my
> experience the aperture stop down mechanism cause even more problem, was the
> problem caused by lens "flexes"? Could be!
>
> > They are right that to acheive 35mm format resolution on a 2/3" CCD the
> > lens needs to be of higher basic resolution. but they haven't acheived
> > this level with their CCD yet. A good zuiko can image 100 lines/mm,
> > which is a feature size of 10micron. Their CCD pixel is nealy as big, at
> > 8 microns. To acheive equivalent resolution they would need to be down
> > to less than 5micron. So, who are they kidding!
> >
>
> Can't catch your point, as the CCD pixel is so small they need higher
> resolution lens, that should be true.
>
> > If 'flexing' is such a problem then so will be temperature changes,
> > which can easily cause flexing of the order of 5microns.
> >
>
> Temp changes already cause problem on the lenses, so the long one has
> infinity mark over infinity. But accurate focusing can solve the problem. If
> a lens is "flexing" during exposure (caused by mechanical action like
> stopping down the aperture) that is no way to solve.
>
> > As I said, many thanks for directing me to it. I will be checking some
> > of their statements with my colleagues. But on my first viewing I would
> > say they get full marks for marketing hype and very poor marks for their
> > science.
> >
>
> Again, you should not demand too much for such illustration.
>
> C.H.Ling
>
> > regards
> >
> > Chris Barrett


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