[rollei_list] Re: Does the Quality of a Lens Affect Grain?
- From: "Peter K." <peterk727@xxxxxxxxx>
- To: rollei_list@xxxxxxxxxxxxx
- Date: Tue, 2 Dec 2008 08:34:26 -0800
Glad you agreed after all Richard. ;-)
On Mon, Dec 1, 2008 at 1:29 PM, Richard Knoppow <dickburk@xxxxxxxxxxxxx> wrote:
>
> ----- Original Message ----- From: "Peter K." <peterk727@xxxxxxxxx>
> To: <rollei_list@xxxxxxxxxxxxx>
> Sent: Monday, December 01, 2008 10:48 AM
> Subject: [rollei_list] Re: Does the Quality of a Lens Affect Grain?
>
>
> Yes, more grainy. It is simply not resolving as well in many instances
> a result of not passing enough light (coatings) which can result in
> grain. I am sure there are those that may say otherwise, but this is
> my opinion.
>
> On Sun, Nov 30, 2008 at 8:07 AM, Elias Roustom <eroustom@xxxxxxxxxxx> wrote:
>>
>> I know there's no comparison between the quality of the lens on my Rollei
>> 35
>> and my Rollei Giro 90, but is it possible that in addition to difference
>> in
>> contrast, the cheaper lens would make the images more grainy (or less
>> smooth)?
>>
>> E.
>
> I think I understand what Peter is getting at but I _do_ disagree with
> it. Film does not work that way. While some film as more than one coating,
> generally to extend the latitude. More modern emulsions achieve the same
> purpose with a mixture of silver particals. Also, generally modern emulsions
> are thinner than those of the past mostly to improve sharpness. In the
> older, thick, emulsions, the light striking the surface became diffused as
> it passed deeper into the emulsion so that the image was sharp at the
> surface but became more blurred as it went deeper. Of course, the light also
> became attenuated as it was scattered so the overall image remained pretty
> sharp. However, sharpness also decreased with increasing exposure. This is
> the primary reason the film speed system in use now (ISO standard method) is
> designed to give the minimum exposure that will result in good tone
> rendition.
> Grain also varies with average density becoming greater as the density
> increases, another reason for keeping negatives on the thin side.
> Now, its also true, and I think this may be what Peter is getting at,
> that the sensitivity of the silver halide grains, and the size of the image
> silver that develops from them, varies with their size. The finer grains are
> less sensitive than the coarser ones. Also, grain tends to increase with
> development time. So, an underexposed negative may look grainier than a
> properly developed one. If the negatives from a blurry camera are being
> developed more than those from a sharp camera in order to increase the
> apparent contrast, that would also increase the grain.
>
> There is something also in the idea that an image which is confined
> strictly to the surface may look grainier than one which extends into the
> emulsion a bit since what we see as grain is actually the statistical
> combination of many silver grains. When there are more to combine the imager
> looks less grainy. Individual silver grains are nearly submicroscopic and
> are not visible when using a grain focuser on an enlarger. What is seen
> there is the "clumping" of grains at various depths in the emulsion. The
> fact that visible and printible grain is the result of a stochastic process
> also explains why the Callier effect exists. Simply that diffused light
> striking the emulsion on one side is less likely to be blocked by the grains
> at various depths, that is, by striking the surface at many angles, some
> will be scattered and tunnel around the denser areas to wind up going toward
> the lens where collimated light will be scattered away from the optical path
> to the lens. All this is to say that grain is a physical effect not affected
> directly by the nature of the image or lens.
>
> However, having said all that I agree more with the idea that a blurry
> image may _look_ grainier than a sharp one because the eye is more more
> likely to detect the grain in areas of continuous tone especially in the mid
> grays.
>
> --
> Richard Knoppow
> Los Angeles, CA, USA
> dickburk@xxxxxxxxxxxxx
>
> ---
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--
Peter K
Ó¿Õ¬
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