Sheet film not square

[JohnF]

I am using 5x4 sheet film in a Wista 45DX.
Occasional frames are not being exposed ‘squarely’ in that the exposed film is slightly oblique to the edges of the film.
I have yet to see whether it happens with only one particular film holder but can I ask as to what might lead this to happen?
I am thinking that I may have loaded the film poorly but the film holder has rails that should keep the film in the right position. Or perhaps I didn’t insert the film holder in the camera correctly but I always try to check it is properly seated.
What do you think?
Thanks

[Serge S]

I get that with Foma film, usually not an issue with Ilford or Kodak.
Also - sometimes it may shift in the film holder.
You can tap the holder to settle/right the film I think...

[ic-racer]

The film should be rectangular. You can check the two diagonals which should measure the exact same distance.

Contact the film manufacturer and see what they say if you send the defective film back to them.

[Fred L]

There's some play in the rails so uneven edges can happen. I try to tap my holders to seat the film better before loading into the back. But what ^ poster said above about measuring to see if film is squared.

[BrianShaw]

what ^ poster said above about play and tapping...

[Doremus Scudder]

If the image area is not aligned with the film rectangle (i.e., the image is skewed on the film and the rebate is not even), then you have likely mis-loaded your film. If one edge of the film is not under the retaining rail on one side, that is what happens. Work on your loading technique.

I always pull up gently on both sides of the film after loading a holder to make sure it is securely seated under both rails.

Best,

Doremus

[JohnF]

Thanks for the replies. I think Doremus is right - I need to take more care with loading. I always feel for the lugs on the rails and ensure that the film is passing correctly beneath them but will check more stringently that the sheet feels ‘set’ correctly before locking it in.

[Drew Wiley]

It is impossible for ordinary film holders to seat film completely right. There has to be some wiggle room in there. Only with something like a pin-registered vacuum back or special holder, along with an especially designed extra-rigid camera, or a graphics process camera, can this issue be consistently and totally avoided. Otherwise, one must correct for it during printing or digital editing.

But on a more conventional level, the issue is more noxious in the case of either uncharacteristically thin sheet film, or even thick films which tend to have more ragged or sharper edges and corners resisting completely smooth insertion (like I've encountered with Foma sheet film myself). Just requires a little more conscious care and double checking when inserting these in the first place.

[BrianShaw]

Thanks for the replies. I think Doremus is right - I need to take more care with loading. I always feel for the lugs on the rails and ensure that the film is passing correctly beneath them but will check more stringently that the sheet feels ‘set’ correctly before locking it in.

If you really want validation, post a picture of the negative in question.

[Vaughn]

I recommend to tap the holder on one's palm before inserting into the camera. The larger the format the more this becomes important (IMO -- although perhaps less of a problem with panoramic formats -- 8x20, etc). Of course, if one has sky in the image and IF there is dust in the holder, that tap sends it down to the sky!

But several times in the last 40 years I have made long exposures where the film starts out crooked in the holder, and falls into its proper place mid-way thru the exposure. One corner usually is still pretty sharp, though...

All my exposures are long under the redwoods, so tapping has become automatic.

I would also consider that the crooked film could have been loaded squarely -- the film in film holders is free to move around and get crooked while being transported (especially if stored flat) -- and moves in the holder when the holder is turned in one's hands. Tapping the holder is cheap insurance...but keep your holders clean!