film warping in 6x9s

I am very aware that in 6x9 cameras the warping of the film can throw
out focussing. I'll be taking some 6x9 shots soon with a rollfilm
camera. Is there an optimum time I should leave after I have wound
onto the next frame to get a minimum warping? And if somebody can
recommend this optimum length of time to leave the film to recover
from coming off the spool and moving into place, then is there a
feeling for the amount of warping still remaining in decimal fractions
of a millimeter?

"RolandRB" wrote in message
om...
I am very aware that in 6x9 cameras the warping of the film can throw
out focussing. I'll be taking some 6x9 shots soon with a rollfilm
camera. Is there an optimum time I should leave after I have wound
onto the next frame to get a minimum warping? And if somebody can
recommend this optimum length of time to leave the film to recover
from coming off the spool and moving into place, then is there a
feeling for the amount of warping still remaining in decimal fractions
of a millimeter?

Shoot with a Rapid Omega and you wont have to worry about film warping.
To answer your question, .0001mm

RolandRB wrote:
I am very aware that in 6x9 cameras the warping of the film can throw
out focussing. I'll be taking some 6x9 shots soon with a rollfilm
camera. Is there an optimum time I should leave after I have wound
onto the next frame to get a minimum warping?

I think that problems caused by the film developing a set
are the domain of perfectionists. One big problem with
6x9 folders is that people sometimes open the bellows
too quickly. The partial vacuum produced can cause the
film to bow outwards, this can cause fairly severe focus
problems. Another thing to watch is how well the end of
the backing paper is attached to the takeup spool. I like
to wrap the backing paper a couple times around the spool
and test it under tension before inserting the spool into
the camera. Before I adopted this procedure, I used to
sometimes find that the film and backing paper were not
wound tightly around the takeup spool when I removed it
from the camera. If this happens to you, it is a sure
sign that the film was not under the proper amount of tension
when it moved through the camera, and it probably results
in a lack of film flatness in addition to loosely wound spools.

Peter.
--

a

or see http://medfmt.8k.com/mf/flat.html and
http://medfmt.8k.com/mf/critical.html for more math, examples of ranges of
warpage, and so on from real world tests and so on..


hth bobm
--
************************************************** *********************
* Robert Monaghan POB 752182 Southern Methodist Univ. Dallas Tx 75275 *
********************Standard Disclaimers Apply*************************

RolandRB wrote:

I am very aware that in 6x9 cameras the warping of the film can throw
out focussing. I'll be taking some 6x9 shots soon with a rollfilm
camera. Is there an optimum time I should leave after I have wound
onto the next frame to get a minimum warping?

Depends on the camera. Some don't have this problems, with some it -is- a
problem.

--

Stacey

RolandRB wrote:

I am very aware that in 6x9 cameras the warping of the film can throw
out focussing. I'll be taking some 6x9 shots soon with a rollfilm
camera. Is there an optimum time I should leave after I have wound
onto the next frame to get a minimum warping? And if somebody can
recommend this optimum length of time to leave the film to recover
from coming off the spool and moving into place, then is there a
feeling for the amount of warping still remaining in decimal fractions
of a millimeter?

I have seen two contradictory recommendations:

1. Wait, till the film has relaxed and flattened out.
2. Shoot immediately, before the tension of the film is lost.

Go figure.

-- Lassi

Lassi Hippeläinen wrote in message ...
RolandRB wrote:

I am very aware that in 6x9 cameras the warping of the film can throw
out focussing. I'll be taking some 6x9 shots soon with a rollfilm
camera. Is there an optimum time I should leave after I have wound
onto the next frame to get a minimum warping? And if somebody can
recommend this optimum length of time to leave the film to recover
from coming off the spool and moving into place, then is there a
feeling for the amount of warping still remaining in decimal fractions
of a millimeter?

I have seen two contradictory recommendations:

1. Wait, till the film has relaxed and flattened out.
2. Shoot immediately, before the tension of the film is lost.

Go figure.

Figuring now....

When you wind on the film it has just gone over a roller and been bent
through an angle so I would guess that to take the shot immediately
would not be a good idea. But if you leave it in place for too long
then maybe it will gradually warp. I'm guessing that a time of one to
two minutes after winding on would be best.

"RolandRB" wrote in message
om...

When you wind on the film it has just gone over a roller and been bent
through an angle so I would guess that to take the shot immediately
would not be a good idea. But if you leave it in place for too long
then maybe it will gradually warp. I'm guessing that a time of one to
two minutes after winding on would be best.

I think you will find that for 99.9% of your shooting it won't make any
difference.
Like I said before, if flatness is really an issue than use a Rapid-Omega
and settle for a 6x7 format.

"Mike" wrote in message hlink.net...
"RolandRB" wrote in message
om...

When you wind on the film it has just gone over a roller and been bent
through an angle so I would guess that to take the shot immediately
would not be a good idea. But if you leave it in place for too long
then maybe it will gradually warp. I'm guessing that a time of one to
two minutes after winding on would be best.

I think you will find that for 99.9% of your shooting it won't make any
difference.
Like I said before, if flatness is really an issue than use a Rapid-Omega
and settle for a 6x7 format.

I can't really settle for that when I already have some 6x9s.

This got me wondering. If film bulge is a problem even for the 35mm
format (which I am sure we have all heard about here cough spit)
then why didn't people use the rewind lever to give a bit of extra
tension in that strip of cine film every time they took a shot?
Surely that would have flattened the film a treat?

I always "tighten up" my film when shooting 35mm. 120's a little different as there's tension there from the
beginning. I think though that you'd probably get flatter results with 2x3 sheet film in the right holder than
6x9 roll film.

RolandRB wrote:

"Mike" wrote in message hlink.net...
"RolandRB" wrote in message
om...

When you wind on the film it has just gone over a roller and been bent
through an angle so I would guess that to take the shot immediately
would not be a good idea. But if you leave it in place for too long
then maybe it will gradually warp. I'm guessing that a time of one to
two minutes after winding on would be best.

I think you will find that for 99.9% of your shooting it won't make any
difference.
Like I said before, if flatness is really an issue than use a Rapid-Omega
and settle for a 6x7 format.

I can't really settle for that when I already have some 6x9s.

This got me wondering. If film bulge is a problem even for the 35mm
format (which I am sure we have all heard about here cough spit)
then why didn't people use the rewind lever to give a bit of extra
tension in that strip of cine film every time they took a shot?
Surely that would have flattened the film a treat?