[rollei_list] Re: WTB: SL66 thingies
- From: "Eric Goldstein" <egoldste@xxxxxxxxx>
- To: rollei_list@xxxxxxxxxxxxx
- Date: Mon, 22 May 2006 13:11:40 -0500
Actually Peter, I'm letting you set the record for misinformation on a
single post... I think by this point, you've surpassed your old
record... ;-)
If you google light transmission and lens coatings you get many
references. Here is just one:
http://www.astrosurf.com/lombry/reports-coating.htm
It puts modern single coatings at 1.5% loss and modern top-end
multicoatings at .25%. My source however is actually The Chief Optical
Designer at Cooke, whome a met some years ago. He said a good average
figure for modern MC loss is about .5% per surface for photographic
lenses. At a meeting I attended where he presented, someone asked the
same question Peter did, basically, do lenses with fewer air/glass
surfaces perform better than more complex designs. He gave the answer
I repeated here, that that is old thinking. More optical
elements/degrees of freedom on fine lenses mean higher order
corrections, and with modern coatings you generally really don't need
to worry about losses. Some of Cooke's fine cine lenses feature 11 or
more elements; these are very highly corrected, high contrast
lenses...
So in answer to the original question, the 5 element Planar and the 7
element Planar are two fundamentally different types of lenses, and
more lenses element in a design generally means more degrees of
freedom and higher order correction of abberations.
Jerry, the LaSalle would have been completely out of my price range...
Peter, feel free to shut up at any time ;-)
Eric Goldstein
--
On 5/22/06, Peter K. <peterk727@xxxxxxxxx> wrote:
I do not think there is a source. He probably wanted to shut me up. :-)
On 5/21/06, Richard Knoppow <dickburk@xxxxxxxxxxxxx> wrote:
>
> ----- Original Message -----
> From: "Don Williams" < dwilli10@xxxxxxxxxxxxx>
> To: <rollei_list@xxxxxxxxxxxxx>
> Sent: Sunday, May 21, 2006 8:45 PM
> Subject: [rollei_list] Re: WTB: SL66 thingies
>
>
> > At 07:01 PM 5/21/2006 -0700, you wrote:
> >>Peter,
> >>
> >>Yeah, you do 99.5 for say 11 air to glass surfaces and you
> >>end up with a number that is not quite so large.
> >>
> >>BTW, you should tell Eric that you drive a La Salle, not a
> >>DeSoto!
> >>
> >>Jerry
> >
> > Jerry,
> >
> > What lens design do you have in mind that has 11 air to
> > glass surfaces?
> >
> >
> >
> > Don Williams
> > La Jolla, CA
> >
> I can't answer for Jerry but there are plenty of zoom
> lenses that have this many. They would be impossible without
> effective anti-reflection coating.
> I questioned Eric because I am curious about his source,
> not because I think he is wrong. I have simply never seen a
> statistic on rejection rates of lens coatings. The
> technology involved is very advanced now. Thin film
> deposition is used in the manufacture of electronic
> components and elsewhere. Multiple anti-reflection coating
> on camera lenses is fairly simple compared to some other
> applications of the same or similar technology.
>
> ---
> Richard Knoppow
> Los Angeles, CA, USA
> dickburk@xxxxxxxxxxxxx
>
> ---
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--
Peter K
Ó¿Õ¬
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