RE:70mm

["Willem-Jan Markerink" <w.j.markerink@xxxxx>]

On 12 Jan 97 at 1:58, Jim Henderson wrote:

> >>This is still at the official 4.5m (15ft) length the 70mm cartridges
> >>were designed for? My Mamiya literature indicates 54 exposures (Bob
> >>Shell's book for instance), without stating physical length. I know
> >>that aerial film can be much thinner and hence longer, but that
> >>still could cause problems with the film counter (how far does that
> >>one go btw?) or development.
> The Mamiya back has a counter up to 55 exposures--sorry about the slip of the
> digit...  There are TWO reels available, however, one holds 55 exposures the
> other must be the shorter one to which you refer.

Do you mean two different sized spools inside the 70mm cartridge?
 
> >>Does it comply to 35mm HIE within one stop, or is it different?
> >>Wratten #25 for me (35mm) boils down to 50 ASA, #87C eats two stops 
> >>more.  
> 
> Well, "comply" is a subjective word.  Many people who list their film speeds on
> the list vary considerably, and I think much has to do with meter, water, and
> developer.  TMAX-RS is designed to produce maximum film speed.   My personal
> experience is that HIE in ANY format size processed in TMAX-RS diluted 1:9,
> processed at 70F results in an effective speed of 200 using either the Pentax
> spotmeter, Minolta autoflash spotmeter, or my internal Canon F-1 meter--used
> without the filter over the meter.  If you meter through the filter, you will
> have to calibrate it as you describe in your FAQ.  BTW, DK-50 will also give the
> same effective film speed.

I more or less assumed you also shoot 35mm HIE from time to time, and 
develop it in the same TMAX-RS solution....that is not the case 
perhaps? No direct comparison 35mm vs 70mm?

Btw, have mentioned this TMAX(-RS) option to a friend a few times, but 
he feels that any gain in speed is detrimental for the performance 
of HIE (both contrast and sharpness). Is convenience the only gain 
when going to TMAX, at the loss of other qualities?

> >>Btw, even though in new condition: I can't get the (film back) counter 
> >>running....
> 
> William, you must first load film onto a takeup reel.  The counter is activated
> once film is being taken up into the second cartridge

I know it must be something like that, but I couldn't find any kind 
of sensor telling the camera the difference between film and no-film.
In hindsight it must work off the camera too, since the back is 
Graflock compatible, to be used on any kind of view camera.

(PS: if anyone has a Mamiya G-adaptor laying around; I am interested
in one for a friend with a Mamiya Universal Press camera. With this
adaptor he could use my back on his camera, and the small register
(film-flange distance) of the Universal could make
interesting experiments possible with other lenses.

> >>Btw, did you ever try the vacuum system to see whether it makes any 
> >>difference in performance? 
> 
> The vacuum system, which includes an air bulb and thin hose to connect to the
> back allows the user to create a vacuum between the film plate and film.  This
> is necessary when no film is advanced for a while.  The next time it is wound,
> the film has a "kink" in it where it made the 180 turn around the side of the
> back.  I usually just advance the film two frames and forget it  Believe me,
> the film is kept quite snug against the back!

Assuming you bought the RB 70mm back new (?): was this air bulb and 
hose included in the kit, as it says in the brochure?
I guess the previous owner of my back threw it away, it wasn't 
included....:-((
 
> >>PS: are you aware that Beattie makes a 70mm long roll/bulk back, either with
> or 
> >>without data imprint? (choice of motordrive as well I believe)
> >>When I asked B+H about Mamiya 70mm backs some year ago, Henry Posern
> >>sent me Beatty literature; he even mentioned to be sure that all 
> >>parts would be included in case of me buying used stuff. 
> >>Even though a mistake, I would never have known about Beatty backs
> >>otherwise....:-))
> 
> Do you have any information or references for the Beattie back??  send it to me
> if not too much trouble.  Thankx

<grin>
I even found the brochures where I *thought* I left them....pleasant 
surprise....wished that happened more often....:-))
A brief summary for others (I sent Jim scans of the brochure (0.5MB), if 
anyone is interested let me know, or contact Beattie for a set):
There are 5 different long roll film magazines for this "Converter 
67" system:
- D-67, full format 70mm film, 6x7cm or 2 3/8" x 2 11/16"
- D-56, split 70mm, 6x4.35cm or 2.375" x 1.70"  
- C-55, 35mm borderless (non-perforated), 3.2x4.35cm or 1.26" x 1.70"
- C-48, 35mm, 24x36mm or 0.95" x 1.42" 
- F-80, 46mm, 4.35x5.7cm or 1.70" x 2.25"

All the above are available as electric backs, and only the normal
35mm back is not available in a manual version.
If I read their pricelist correctly, then an all manual constellation 
without data imprint is close to the smaller OEM Mamiya 70mm back.

All magazines accept 100' (30m) of film, on 70mm resulting in 415 
full frames, or 650 split ones. They also have the RB/RZ feature of 
rotating between landscape and portrait mode.

Beattie Systems Inc.
P.O. Box 3142
Cleveland TN 37320
Voice: 1 800 251 6333 or (+1) 615 479 8566
Fax: (+1) 615 476 7171



--
Bye,

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      The desire to understand 
is sometimes far less intelligent than
     the inability to understand


<w.j.markerink@xxxxx>
[note: 'a-one' & 'en-el'!]

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Topic No. 11