[rollei_list] Re: looks like ... Agfa Scala

----- Original Message ----- 
From: "Mark Rabiner" <mark@xxxxxxxxxxxxxxxx>
To: <rollei_list@xxxxxxxxxxxxx>
Sent: Tuesday, May 31, 2005 6:14 AM
Subject: [rollei_list] Re: looks like ... Agfa Scala


> Agfa black and white films especially the 100 has for many 
> of my
> photographer friends for decades a long reputation for 
> being about the
> smoothest "straight line" films you can get. Up there with 
> Verichrome pan.
> The famous cult recently departed black and white film 
> which at one point
> was they only film they made in certain sizes.
>
> Now those characteristic curve charts don't seem to 
> reflect (and I hate to
> make an "S" out of myself). So my friends all these years 
> perhaps were wrong
> in some way.
> But all I know is printing Agfa film, especially the 100 
> sure makes you
> believe this false "straight line" impression, if it is 
> false, we have on
> the technical description at least in what is going on.
>    for some reason  or another.
>
> It's smooth and creamy film.
>
> Never liked film "chunky style".
>
> Mark Rabiner
> Photography
> Portland Oregon
> http://rabinergroup.com/

  If you are refering to the curves in the Agfa datasheet I 
think I know why they look S shaped. If you examine the 
graphs you will find they cover a log exposure range of 4 
beginning with the toe, this is nearly double the range 
shown by Kodak on its graph. As a result Agfa's graphs show 
the beginning of the shoulder, which is beyond the range of 
the Kodak graphs. All films have an S curve if you look at 
the entire curve. Agfapan 100 is a medium-toe film with a 
reasonably long and fairly straight characteristic. Its hard 
to read the curve exactly and its a smoothed average. It 
appears to my eye that the curve may have a slight belly 
upwards. This would result in rendering mid-grays slightly 
brighter than a straight line film for given shadow and 
highlight values. Agfapan 400 appears to have a slightly 
straighter and longer mid section but also the whole curve 
is moved to the right because the log exposure calibration 
is the same for both graphs. This has teh effect of moving 
part of the shoulder off the graph. The published film 
curves from any manufacturer give no more than a general 
idea of the film's performance, actual photographs will tell 
you more. From my experience with APX-100 the curve looks 
about right. The film has excellent mid tone rendering.
   I have refered to a cross section of Agfa B&W films here. 
Its not on this data sheet, which is the one currently on 
the web site. I will have to look over older data to try to 
find it. This sheet has a cross section of Agfa color film.

---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx 

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