[rollei_list] Re: Lens coatings and veiling flare.

Richard -

I know that the C has been serviced relatively recently as this was
discussed here... if the lens was not cleaned carefully at that time,
shame on whoever did it...


Eric Goldstein

--

On Tue, Jul 7, 2009 at 3:27 PM, Richard Knoppow<dickburk@xxxxxxxxxxxxx> wrote:
>
> ----- Original Message ----- From: "Sanders McNew" <sanders@xxxxxxxxx>
> To: <rollei_list@xxxxxxxxxxxxx>
> Sent: Tuesday, July 07, 2009 4:52 AM
> Subject: [rollei_list] Lens coatings and veiling flare.
>
>
>> I shoot a variety of older Rolleiflexes --
>> a 3.5E and a 2.8C getting most of the
>> work.  Their weakness, in my use, has
>> always been veiling flare when shooting
>> a strongly backlit subject, or in other
>> conditions where the sun or a bright
>> reflection is in the frame.
>>
>> Does anyone onlist know when F+H
>> or its lens suppliers upgraded the lens
>> coatings on the TLRs?  Are later TLR
>> models more effective at suppressing
>> veiling flare in these conditions?  Do
>> I need to ask Austin for his GX to tame
>> this beast?
>>
>> Sanders
>> ---
>
>    Check your lenses for internal haze. Shine a flashlight through the lens
> with the shutter and iris open. A very small amount of haze will destroy
> image contrast. The haze can be cleaned off but usually requires opening the
> lens.
>    The difference between single layer coatings and later multiple layer
> ones is mostly exhibited in color contrast. The single layer is most
> effective at a single wavelength and falls off in effectiveness above or
> below that. Usually single layer coatings are peaked for either green or
> blue light. The residual reflection from the lens will indicate the peaked
> wavelength because it is its compliment. Lenses peaked for green light have
> magenta reflections and those peaked in the blue have amber reflections.
>    Multi-coating broadens out the band of wavelengths, or colors, where the
> coating is effective. Double coatings were the first but modern lenses may
> have several coatings. A really good broadband coating should have nearly no
> reflection and that with no residual color. I doubt very much if any
> consumer lenses have this grade of coating but a practical coating will come
> close.
>    The main visual effect of a multiple coated lens in photographs is an
> improvement in color purity and saturation although it will certainly
> improve monochrome contrast as well. The main effect of flare is to lower
> _shadow_ contrast, in effect similar to a long toe film. Haze has a similar
> effect but can be considerably greater than the internal reflection flare
> from relatively simple lenses.
>
> --
> Richard Knoppow
> Los Angeles, CA, USA
> dickburk@xxxxxxxxxxxxx
> ---
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