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"film" and "digital" lenses



 
 
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  #11  
Old May 30th 05, 06:08 PM
Mr. Mark
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Someone said in alt.photography that "film" lenses are designed to focus
the different color wavelengths differently to make up for the layered
emulsion in film.


Thats BS..


Thanks all to answered. It sounded like a load of crap, but I'm no expert.


--
Mark

Photos, Ideas & Opinions
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  #12  
Old May 30th 05, 07:57 PM
Ben Rosengart
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On Mon, 30 May 2005 17:07:35 GMT, Mr. Mark wrote:
I heard there is a coating on the rear element to prevent reflections
off the sensor for digital lenses though I've not seen any example of
these reflections so I assume it's quite a minor issue.


Wouldn't film do the same thing? It's shiny plasticy stuff after all.


Not as shiny.

BTW, you wouldn't necessarily see the reflections, they can manifest
as a general lack of contrast.

--
Ben Rosengart (212) 741-4400 x215
Sometimes it only makes sense to focus our attention on those
questions that are equal parts trivial and intriguing.
--Josh Micah Marshall
  #13  
Old May 30th 05, 07:57 PM
Ben Rosengart
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On Mon, 30 May 2005 17:07:35 GMT, Mr. Mark wrote:
I heard there is a coating on the rear element to prevent reflections
off the sensor for digital lenses though I've not seen any example of
these reflections so I assume it's quite a minor issue.


Wouldn't film do the same thing? It's shiny plasticy stuff after all.


Not as shiny.

BTW, you wouldn't necessarily see the reflections, they can manifest
as a general lack of contrast.

--
Ben Rosengart (212) 741-4400 x215
Sometimes it only makes sense to focus our attention on those
questions that are equal parts trivial and intriguing.
--Josh Micah Marshall
  #14  
Old May 30th 05, 08:19 PM
DoN. Nichols
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In article ,
Alan Browne wrote:
Martin Francis wrote:

Further, the film companies have differing emulsion build up designs,
including Fuji "4th layer" in some negative films. I never heard of
needing special lenses for that...



Or special lenses for black and white...


Good point.


I seem to remember a special three-layer B&W film from perhaps
the late 1960s or early 1970s. I have never used it, but I read the
reviews of it with great interest.

Each layer was a different ISO, and by selective color
filtration in the enlarger, you could select the layer which had what
you wanted.

IIRC, the review showed a shot of a clear glass light bulb, in
operation, and from one layer, you could get the image of the glass
envelope (with the filament vastly over-exposed), while from another,
you could get an image which showed detail of the glowing filament.

But, granted, this is an extreme example, and as far as I know,
the film had a very short life in the market -- just too special
purpose. :-)

Enjoy,
DoN.

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  #15  
Old May 30th 05, 08:24 PM
DoN. Nichols
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In article ,
Mr. Mark wrote:
I heard there is a coating on the rear element to prevent reflections
off the sensor for digital lenses though I've not seen any example of
these reflections so I assume it's quite a minor issue.


Wouldn't film do the same thing? It's shiny plasticy stuff after all.


The film itself is (that is the plastic backing material), but
the emulsion which faces the lens is typically a matte gray prior to
development. Thus it is not capable of specular (mirror-like)
reflections.

There is also typically a darker coating on the back of the film
to reduce reflections from particularly bright highlights which can
punch through the emulsion and reach the back. This is dissolved in the
processing of the film.

Enjoy,
DoN.

--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---
  #16  
Old May 30th 05, 09:49 PM
Alan Browne
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DoN. Nichols wrote:



I seem to remember a special three-layer B&W film from perhaps
the late 1960s or early 1970s. I have never used it, but I read the
reviews of it with great interest.

Each layer was a different ISO, and by selective color
filtration in the enlarger, you could select the layer which had what
you wanted.

IIRC, the review showed a shot of a clear glass light bulb, in
operation, and from one layer, you could get the image of the glass
envelope (with the filament vastly over-exposed), while from another,
you could get an image which showed detail of the glowing filament.

But, granted, this is an extreme example, and as far as I know,
the film had a very short life in the market -- just too special
purpose. :-)


I love trivia like that. People tried to achieve new things in smart
ways. Like you say, a little too special for a market that demands fast
access to the film and reasonable turnaround. That film seems to have
required too much post processing to be any fun to use.

Cheers,
Alan.


--
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  #17  
Old May 31st 05, 03:46 AM
RichA
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On Mon, 30 May 2005 16:49:50 -0400, Alan Browne
wrote:

DoN. Nichols wrote:



I seem to remember a special three-layer B&W film from perhaps
the late 1960s or early 1970s. I have never used it, but I read the
reviews of it with great interest.

Each layer was a different ISO, and by selective color
filtration in the enlarger, you could select the layer which had what
you wanted.

IIRC, the review showed a shot of a clear glass light bulb, in
operation, and from one layer, you could get the image of the glass
envelope (with the filament vastly over-exposed), while from another,
you could get an image which showed detail of the glowing filament.

But, granted, this is an extreme example, and as far as I know,
the film had a very short life in the market -- just too special
purpose. :-)


I love trivia like that. People tried to achieve new things in smart
ways. Like you say, a little too special for a market that demands fast
access to the film and reasonable turnaround. That film seems to have
required too much post processing to be any fun to use.

Cheers,
Alan.


Ilford XP1 = garbage. It had supressed grain but was so finicky when
it came to contrast it wasn't worth using.
-Rich
  #18  
Old May 31st 05, 03:40 PM
Mr. Mark
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"Ben Rosengart" wrote in message

BTW, you wouldn't necessarily see the reflections, they can manifest
as a general lack of contrast.


I hadn't considered that. Thanks.


--
Mark

Photos, Ideas & Opinions
http://www.marklauter.com


  #19  
Old May 31st 05, 03:45 PM
Cheesehead
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From my personal evaluation of film lenses on digital ...
.... it seems to be a generational thing. Some particular coatings that
have a desired effect on film have a negative effect with digital.
My Pentax SMC 30/2.8 is outstanding for both film and digital, as are
the newer Pentax-F 50/1.7 and Pentax-FA 50/1.4. But the "A" series
lenses (Pentax-A 50/1.7, 35/2, and 100/2.8 [non-macro]) are only
average lenses. There's some color fringing toward the edges unless I
correct the white balance.
So the answer is yes and no. Some film lenses don't perform well with
digital. But some do. It's not necessarily because they were film
lenses. There is a correlation, but it is not a causal relationship.

Conversely, digital lenses should always perform well with film,
especially with traditional b&w with its single-layer emulsion. In the
Pentax world, the new Pentax-DA 40/2.8 is a tempting new offering,
well-suited for both fomats. (But I'm not quite ready to shell out
$399 for it.) Yes, it's another pancake. And a pretty one at that.

Collin
KC8TKA

  #20  
Old May 31st 05, 03:48 PM
Ben Rosengart
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On 31 May 2005 07:45:45 -0700, Cheesehead wrote:

Conversely, digital lenses should always perform well with film,


Well, watch out for "digital" lenses that project a smaller image circle.
You'll get *severe* vignetting on a film camera.

--
Ben Rosengart (212) 741-4400 x215
Sometimes it only makes sense to focus our attention on those
questions that are equal parts trivial and intriguing.
--Josh Micah Marshall
 




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