Problem with slight film rotation

[Leonard Evens]

I've noticed when scanning that despite my best efforts to level the camera, including double checking on the gg, I find after development that my images are rotated slightly on the film. The amount is small, between 1/2 and 1 deg, but it is annoying because it results in a slight reduction in the size of the usable image. Checking everything, I've think I've located the problem. There is a slight amount of play in the position of the film in the holder and similarly play in the position of the holder in the camera. I can try to standardize the former when loading and the latter when putting the holder in the camera. But the film could still shift in the holder during transit. I'm using Fidelity Elite film holders.

Does anyone have any tips about avoiding this?

[Stan. Laurenson-Batten]

Leonard. This is a real teaser. I am using the same film holders. I use colour, velvia and Delta B&W. I have never had any of the problems you have encountered. I use a Sinar P1 and find that the location is quite positive. I have heard that film thickness can vary between types and manufacturers, but from my collection of negatives and positives they are all the same size. Are you using maverick film stock?

[Ralph Barker]

Beat it into submission, Leonard. ;-)

In other words, give the holder a tap against your other hand to settle the film to the botton of the holder just before you insert it into the camera. That should solve the rotation problem.

[Leonard Evens]

Thanks all for the advice.

I'm using Portra VC 160 and HP5+ primarily.

I did know about tapping the holder, but I think I hadn't been doing it right. When I remembered I just gave it a light nudge against my hand, which apparently didn't suffice. I just did an experiment and found that a sharp rap on a solid surface on the short edge opposite the slides or on the long bottom edge seems to align it on that edge. I think I will do both to standardize where the film is.

[Peter Witkop]

Are you using the levels on the tripod or the camera to level it? The buble levels on my tripod don't match the buble levels on my cambo, neither of witch exactly agree with a level held up to the ground glass, lined up with the grid lines. Something else to check anyway, hope that helps.

Peter

[Leonard Evens]

Peter,

Neither my camera, a Toho (not Toyo) FC-45X, nor my tripod has levels. I use a simple torpedo level on the rear standard, and I also check the result using the grid lines on the gg. I've also checked that the grid lines are square with the sides of the standard. If the film is properly in place, it should line up pretty well with the grid lines. If the vertical lines in the subject don't converge and line up with the grid lines, the only explanation for a rotated image is that the film is rotated a bit from its proper position in the holder or the holder is rotated slightly in the camera or both.

[Bill_1856]

I doubt that the problem is in the film/holders. How are you determining that the image is level when you compose the picture?

[Leonard Evens]

How do I determine that the image is level?

First I check that the rear standard is plumb by putting a torpedo level vertically on one of its flat surfaces and adjusting the tripod. I have previously checked that the gg surface is parallel to the flat surface I use.

That still leaves the possibility that the rear standard is rotated with respect to a vertical line. I use the torpedo level on the top of the standard and also in another location to check that the rear standard is horizontally level. Again I've previously checked that the gg is consistent with the reference surfaces I use.

I then check this all against the grid lines on the gg. If the rear standard is not plumb, vertical lines in the subject will converge or diverge and that will be obvious when comparing them to the grid lines. Similarly, if the rear standard is not horizontally level, that will also be obvious by comparing the grid lines to the vertical lines in the subject. I've also checked independently that the grid lines on the gg are in fact level when the back is level.

In fact, I could do it all by using the grid lines on the gg, since those are what count, and when I am in a hurry, sometimes I do just that. What I see on the gg should be what I get in the negative, provided the film is not rotated with respect to the gg. But it doesn't hurt to build some redundancy into one's procedures.

I should add that I am very fussy about such matters and I think I have a good eye for it.

Is there anything else I should be doing?

[Bill_1856]

Jesus, Leonard, no wonder you're frustrated -- it would certainly drive me crazy! Have you checked your torpedo level? And are you sure that the grid lines are perfectly parallel to the CFH seating surface of the back? One degree doesn't sound like much, but I almost get vertigo when I see a print that's off that far, so you have my total empathy.

[Andrew O'Neill]

I don't trust rapping my film holders instead I put a very small, thin piece of double-sided tape in the centre of the holder (I use 8x10 film). After sliding a sheet of film in, I give it a couple of blasts of canned air. This holds the film onto the tape. To remove the film from the holder just wiggle it and it'll gradually come out. Tape also prevents the centre of the film from bending outward when camera is pointing downward.

[Armin Seeholzer]

Hi Leonard

I had also so frustrated little shifts in the beginning days and I found it was the Arca F-Line has to much play (1 - 1 1/2mm) with different holders so I started to push the holders always fully to the right side when inserted and it started to improve imidiatly.

Good light!

[Graeme Hird]

I'm with Bill - how frustrating ......

You could use 5x7 format, or you could get slightly wider lenses, or you could take half a step back to regain that lost image coverage.

With around 125mm of film width, losing half a millimetre of each end on those rare occasions where my horizon is a degree out doesn't bother me too much, if I even notice. Maybe my point of view is slightly wider.

As Armin says, good light!

[Al W]

Leonard,

I believe you're dealing with tolerance build up in mechanical alignment of parts. When this happens no mater how much you look at and check individual parts they will always look great, but put them together and they don't work.

I have a couple simple tests for you to try:

(1) Take a piece of paper or cardboard that is about half the width of a film holder and slide it in behind the ground glass. Make sure its pressed firmly against the bottom film holder alignment rail. Open your lens and shine a light in the front of the camera. If the problem is your camera the shadow cast on the ground glass will show the problem. If everything is straight and aligned you've eliminated the bottom film holder guide as the problem. Then make sure the film holder is seating against this surface properly and not being shifted away from it by something else involved.

(2) You can likewise load a sheet of film that has a line drawn through the center into an open holder. Stand the film holder vertically on edge on a flat surface to see if the line down the center of the film in parallel to the flat surface. Tap the film holder different ways to see how much the film moves around and what you need to do to correct it.

Hope it helps