I have a densitometer on the way and

[Sandman]

cannot find an explanation anywhere regarding how to make a test exposure on sheet film with a Stouffer wedge. I don't have an enlarger to use. The descriptions for paper exposure seem very simple but I've no idea how to expose film with what probably needs to be a very short exposure time. Is it possible to do so by mounting the wedge and film in a film holder and using my 8x10 camera to control the light? Also, is is preferable to buy the 4x5" step wedge rather than the narrower strip wedges? I have a 5x7 back for my Deardorff which would seem to hold the film and step wedge pretty well. I would appreciate some guidance from someone who has more experience than I in this regards. Many thanks!

[Ian Leake]

I did this just yesterday with Efke/Adox 25. I used Phil Davis' Beyond The Zone System methodology. It's well worth buying, reading and understanding this book if you want to test film. Here's what I did in summary:

Preparing the step wedge:
1) I used a 5x4 step wedge and mounted it in a 10x8 sheet of paper

Preparing the enlarger:
1) Mounted a shutter with no lens in my enlarger lens panel
2) Positioned the head so I could take an LV 7 reading of the white base board across the area where the step wedge would sit
3) Fixed a guide to the base board so I could place the film and mounted step wedge in alignment under the enlarger

Exposing the film:
1) Switched on the enlarger light and let it settle for a few seconds
2) Fired the shutter at 1/10
3) Switched off the enlarger light
4) Repeat to get multiple sheets of exposed film

Having developed the film yesterday in Rodinal I'm going through the curves analysis today.

I hope this helps.

Ian.

[dancqu]

I seem to recall reading of a method which made a
series of test exposures by pulling the slide a bit more
each exposure. I use a gray board outside and
expose a 120 roll for at least five zones. Dan

[gainer]

Mounting the wedge on a piece of paper and putting it in a film holder is good if you can load the paper between the lens and the film. You must, of course, cut a hole in the paper the size of the wedge. You need a uniform brightness to photograph. IIRC, the 0.7 density of the wedge is about Zone V. If you set your lens and shutter according to an incident light reading, you should get usable results. It might be worthwhile to expose a piece of printing paper without the wedge and develop it to see if your light distribution is uniform. The longer the focal length of your lens, the more likely it is to be uniform. I say printing paper because it is cheaper, and is of high contrast which will emphasize uneven illumination.

[gainer]

You might also refer to The Book of Pyro by Gordon Hutchings. He has good plans for a Zone Board for doing most of the tests you will want to do without using a step wedge and without worrying about evenness of illumination.

[sanking]

Apart from a number of other issues which have been addressed by others a major consideration in the size of the step wedge you buy is the size of the measuring aperture of your densitiometer. One of my densitometers, an X-Rite 810, has a very large measuring aperture (1/4") , which makes use of the smaller Stouffer step wedges hard to read with precision. On the other hand, my Gretag D-200-11 has a measuring aperture which makes reading the small wedge useful.

Sandy

cannot find an explanation anywhere regarding how to make a test exposure on sheet film with a Stouffer wedge. I don't have an enlarger to use. The descriptions for paper exposure seem very simple but I've no idea how to expose film with what probably needs to be a very short exposure time. Is it possible to do so by mounting the wedge and film in a film holder and using my 8x10 camera to control the light? Also, is is preferable to buy the 4x5" step wedge rather than the narrower strip wedges? I have a 5x7 back for my Deardorff which would seem to hold the film and step wedge pretty well. I would appreciate some guidance from someone who has more experience than I in this regards. Many thanks!

[Donald Miller]

cannot find an explanation anywhere regarding how to make a test exposure on sheet film with a Stouffer wedge. I don't have an enlarger to use. The descriptions for paper exposure seem very simple but I've no idea how to expose film with what probably needs to be a very short exposure time. Is it possible to do so by mounting the wedge and film in a film holder and using my 8x10 camera to control the light? Also, is is preferable to buy the 4x5" step wedge rather than the narrower strip wedges? I have a 5x7 back for my Deardorff which would seem to hold the film and step wedge pretty well. I would appreciate some guidance from someone who has more experience than I in this regards. Many thanks!

Considering that you have a densitometer on the way, I will address your questions as you raised them.

If I were attempting to expose sheet film to test without an enlarger, I would tape the step wedge to a piece of unexposed film. Then I would expose the film to a uniformly lit surface with the lens at infinity to focus. (It makes no difference if the surface is in focus so long as the lens is at infinity focus to alleviate bellows extension considerations).

I would expose the film/step wedge to a value of EV 4-7 at 1/2 the box speed of the film. Keep exposures above 1/2 second to avoid reciprocity considerations. Process the film at the developer recommendations for the developer that you are using. This should give you your EI and and DR of the film at the exposure and developer/development time that you have chosen.

If the darkslide of the film holder does not bypass the stepwedge, then you can load the film holder sans darkslide in your darkroom.

I use the smaller step wedge.

[Donald Miller]

Apart from a number of other issues which have been addressed by others a major consideration in the size of the step wedge you buy is the size of the measuring aperture of your densitiometer. One of my densitometers, an X-Rite 810, has a very large measuring aperture (1/4") , which makes use of the smaller Stouffer step wedges hard to read with precision. On the other hand, my Gretag D-200-11 has a measuring aperture which makes reading the small wedge useful.

Sandy

Sandy,

My 810 has a much smaller orifice. I mention this so that if anyone has one of these instruments they can obtain different orifices from Xrite.

[fhovie]

One thing to consider is the entire system of creating a negative - which includes the camera you are using. I like to use my camera shutters and work a roll of film up from less than zone 0 to zone 11 by changing exposure on a wall that is out of focus. Now I have my sutter speed factored into the process as well. Using this method with various cameras, I discovered which ones had slow shutters. For sheet film, I would try pulling the slide back in increments and accomplish the same thing. This is likely not the most scientific way to do it but, like sighting in a rifle, leaves you with a calibrated system.

[sanking]

Donald,

I mistated the size of the measuring area of my 810. It is actualy 4mm, not 1/4".

But point me to the X-Rite site that indicates other mesuring apertures are available for this instrument. My manual contains no information about alternative measuring apertures.


Sandy

Sandy,

My 810 has a much smaller orifice. I mention this so that if anyone has one of these instruments they can obtain different orifices from Xrite.