[rollei_list] Re: 220 vs 120 film flatness
- From: "Austin Franklin" <austin.franklin@xxxxxxxxxxx>
- To: <rollei_list@xxxxxxxxxxxxx>
- Date: Fri, 30 Apr 2010 15:52:57 -0400
Hi Carlos,
There may be no difference for the TLR, but I do not believe that is
universally true for all cameras that support 120 & 220. I believe it's a
registration issue and depends on the film gate, and the pressure plate
mechanism. It seems to me that the 220 setting makes up for the paper
backing, therefore reducing the film gate depth the thickness of the paper.
It would be interesting to note which cameras do have a different film
back/pressure plate setting for 120 vs 220, and which cameras don't.
The Rollei TLR is the only camera that I know of that doesn't. The Plaubel
Makina 670, if I remember right, did have a different pressure plate
setting, as does the Fuji GS645. Rollei 600x & Hasselblad both have
different backs. I'll check the Contax 645.
Regards,
Austin
> -----Original Message-----
> From: rollei_list-bounce@xxxxxxxxxxxxx
> [mailto:rollei_list-bounce@xxxxxxxxxxxxx]On Behalf Of CarlosMFreaza
> Sent: Friday, April 30, 2010 3:15 PM
> To: rollei_list@xxxxxxxxxxxxx
> Subject: [rollei_list] Re: 220 vs 120 film flatness
>
>
> Interesting data Emmanuel. When 220 film appeared in 1965, Rollei R&D
> tried the new film in the TLR, they concluded that 220 film not only
> could work without TLR cameras film guidance modifications, it also
> eliminated any film flatness issue. It was not necessary a special
> position for the film pressure plate.
> There is a perceptible difference when you use 220 film regarding 120,
> with 220 the film transport mechanism works so light that you doubt if
> the camera has film inside, it seems to "float" as you wrote.
> I did not notice a minimal sharpness difference between 220 and 120 films.
>
> All the best
> Carlos
>
> 2010/4/30 Emmanuel Bigler <Emmanuel.Bigler@xxxxxxxx>:
> > CarlosMFreaza a écrit :
> >>
> >> Carl Zeiss did a research about the film flatness using 220
> and 120 film:
> >>
> >> http://tinyurl.com/35kmksu
> >>
> >>
> >>
> http://www.zeiss.de/C12567A8003B58B9/ContentsWWWIntern/134AEE504E8
> 9CD50C12569620039712C
> >>
> >
> > Carlos ! And you could survive for 10 years without using 220 rollfilm,
> > since apparently you missed this article by Zeiss dated year
> 2000 ? ;-);-)
> >
> > The problem apparently came with some fast lenses, in the style of f/2
> > designed for the Contax 645 camera.
> > With our beloved Rollei TLR stopped down to their best aperture, f/8 or
> > f/11, you can sleep quietly : the allowed depth-of-focus is
> plus or minus 8
> > to 11 times yout favourite circle of least confusion ; I know
> that you use
> > something like 25 microns to compute your depth-of-field
> tables, in order to
> > get images in 6x6 that are top-class, it means that you can
> allow flatness
> > defects of about plus or minus 200 to 300 microns.
> >
> > If the flatness problem was really an issue, Chris Perez could
> never find
> > on-film resolutions close to 100 cy/mm with a good old 120 rollfilm on
> > either a Rollei TLR or an Hasselblad with a 120 film back...
> > http://www.hevanet.com/cperez/test/fourcameras.html
> >
> > It means that the actual sharpness available with a well-tued
> Rollei TLR at
> > f/8 is above 90 cy/mm, i.e. you could even choose a circle of least
> > confusion of about 10 microns for you depth-of-field tables !
> >
> > Moreover as far as the Rollei TLR is concerned, correct me if
> I'm wrong but
> > I think that there is no special position of the film pressure
> plate for 220
> > rollfilm ; it means that without its backing paper, 220 film is
> "floating"
> > between the plate and the film gate, with a spacing designed
> for 120 (film +
> > paper) thinckness... except for Rolleis with the glass pressure
> plate. (this
> > is anotther story..)
> >
> > all the best !
> > --
> > Emmanuel
> >
> >
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