Re: 70mm

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

On 10 Jan 97 at 0:27, Jim Henderson wrote:

> I have been using 70mm Kodak Infrared Aerographic Film 2424 since 1987 in a
> Mamiya RB 67 70mm back using Kodak 70mm metal cassettes.

Jim, as a member from the first hour: how could you keep this quiet for 
so long?....8-))
 
> The film is available in 70mm x 150 ft (45.7 m)  with 35mm perforation (Sp 494)
> as Cat. No. 169 0841 from any Professional Kodak Dealer (have them look in the
> Aerial film section of their ordering book).  No information is available from
> Kodak's Web site on this film.

Might indeed be HIE & 70mm (aka Aerographic IR) that was painfully 
lacking on the Kodak site. Aerochrome IR does get a nice exposure, 
even with these two new emulsions. I asked them about it, never got 
an answer. Even mentioned this list, yet never saw any Kodak rep show 
up as a member.

 
> I have been loading HIE directly into the Kodak metal cassettes in TOTAL
> darkness (turn off all fluorescent lights at least 2-minutes prior to loading)
> directly off the metal spool onto which it is wound.  I have not found that you
> need any bulk loader.  I fashioned a dowl rod into a tapered end which fits
> snuggly into the plastic end of the takeup spool inside the 70mm cassette.  I
> placed a finishing nail 90-degrees to the axis of the dowl rod so I could
> "crank" film onto the takeup spool inside the cassette.  Turning the crank
> approximately 60 turns places about 65 exposures inside the cassette.

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.

 
> I rate the film speed at ISO 200 (daylight) with a Wratten 25 (red) filter over
> the camera lens using off-camera metering (without the red filter over the
> meter).  Using an 87C filter lowers the ISO by a factor of 2.5

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.  
 
> I process the film in TMAX-RS developer diluted straight from the concentrate.

Does TMAX-RS result in a higher EI in average?
Is this with a automatic development machine, or manual?

> I mix parts A & B together into the original container.  Dilute the concentrate
> 1:9 using deionized water to minimize pinholes.  Develop for 8-minutes at 70F
> for a cold-light head enlarger with variable contrast paper.  I use a 70mm
> Kinderman reel and tank.

Found two of them for a fraction of the (insulting) new price, 
including a SS contraption to load the exposed film from cartridge to 
reel. I once measured that it accepts the same 4.5m film 
length....does that comply with your 65 shots?
Can it easily be loaded without this contraption?
 
> The major problems surrounding use of this format are those of incorrectly
> closing the 70mm cassette, which allows fogging to occcur in camera.  The other
> area of concern is the felt light trap on the film back.  Replace every 3 years
> if you use the back heavily, as I do.  If you purchase a used back, inspect the
> felt lining for signs of deterioration.  It will cost about US$125 to replace
> the felt, but this is insignificant since the new backs are up around US$1.050.

Darn, I did find such an 70mm RB back for 1/3rd fo that, and it even 
looks as if it has never been used, but the felt it pretty much shot 
(the official "70mm" label sits still faded on the back, as if it has 
been in a shop window all its life).
Btw, even though in new condition: I can't get the counter 
running....I will receive some 70mm cartridges and exposed film to 
practice with in a month or so, but before that: should the counter 
work with no film inside, and no camera body attached? Should it lock the 
film transport handle after transporting one frame? (it can't detect 
shutter release without body attached of course, but pressing any 
kind of sensors ment for that (I think; upper right hand corner while 
looking at the back) do diddly squat). Or is this 70mm back from 
before the RB pro-S foolproof transport and double-exposure 
preventing design?
Btw, did you ever try the vacuum system to see whether it makes any 
difference in performance? Don't think HIE/Aerographic is on the thin 
end of the film thickness scale, but I hate not using such nice 
features....;-))

> I have imaged everything from archaeological artifacts to body portraits and
> have found the option of having 65 exposures available without changing backs or
> reloading film out in the field very nice, indeed!

This was one of my considerations too.
4x5" is too far stretched on my personal convenience scale, but the 
70mm single cartridge capacity sounds even better than 35mm, it might 
even make up for the added clumsiness of MF gear. 

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....:-)) 

--
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. 21