Kodak Step Tablet #2

<p>Is there a way to expose the kodak step tablet #2 on a negative or a print without the use of a sensitometer? Is there a way to get a standardized exposure on it without one?</p>

<p>For stouffer step tablets, is there a chart that I can photograph directly with a dslr?</p>

<p>Thanks for your help.</p>

<p>If you have a darkroom, you could "contact print" the step wedge onto film with a hot shoe flash. Rig up a fixture to hold things in place, so it's repeatable if you want to come back and do more. Use a bit of diffusion material over the flash to make sure it's not projecting an uneven pattern. Since you won't have any idea how much power to use, make one or two initial exposures. After it's developed, you can tell what adjustment you need by looking at the result.</p>

<p>To photograph it, you could rig up a light table, then photograph the wedge taped to it. Mask off the outside area to minimize lens flare (this is a big deal), and take the whole thing into a dark room to photograph it. Even masked off, the darker patches will be affected by flare - you can estimate how much by masking off the brighter part of the step wedge and rephotographing.</p>

<p>Anything in particular that you're trying to learn?</p>

<p>Don't know if it will help, but there is a pdf of an article by Phil Davis on Sensiometry and the Kodak #2 from <em>Darkroom and Creative Camera Techniques</em>, March/April, 1988 at http://btzs.org/Articles/Sensitometry%20Part%202.pdf</p>

<p>Bill - Thanks for the reply. I would like to get an accurate understanding of the latitude of certain mediums. I've been shooting 4x5 and would like to do a characteristic curve of some different films. I've also been shooting fp100b on my 4x5 camera and the latitude of that is much smaller. I'd like to be able to shoot something with a lot of steps (i.e. a step tablet or similar) so I can accurately gauge the film's latitude. I also shoot video on cinema cameras for work and I would like to have a similar tablet to photograph to have as a latitude reference.</p>

<p>JDM, thanks for the link, I will check that out as well.</p>

<p>Hi, I doubt if you'll find a negative film that can fit within the range of that step wedge. (I'm thinking it's 21 steps, with steps of 0.15 density units, giving a total range of 3.0 density, equivalent to 10 f-stops or 1,000:1.)</p>

<p>The easiest way to handle this is to make two exposures, using a good amount of neutral density filtering for one of them. If it's not obvious how this works, think of it like this: the step wedge by itself covers a range of approximately 0 to 3.0 density units. If you now sandwich this with a piece of 3.0 neutral density filter, the step wedge combined with ND covers a range of 3.0 to 6.0 density. This is equivalent to a range of 20 f-stops, or 1,000,000:1. You don't want to get a gap between the two exposures, where a certain bit of film density is missing, so you would prefer to have the ND filter a bit less than 3.0. (You can match up the two curves by essentially sliding the log-exposure axis side to side until the film density matches.)</p>

<p>The million to one luminance recording range may sound far fetched, so here's a link to a graph I posted some time back. It was done by some Kodak people who wondered if T-max films could handle this range (and it did).<br>

<a href="/film-and-processing-forum/00YN4U">http://www.photo.net/film-and-processing-forum/00YN4U</a></p>

<p>When you use a camera to actually photograph the step wedge, the lens image won't be able to come anywhere near this range because of lens flare. (All of the darker steps will be swamped out by a veil of "fogging" light.) So if you want to compare a contact-printed step wedge vs a photographed step wedge, be aware of this issue. Good luck with the testing.</p>

<p>By the way, since you mentioned using a 4x5 camera, some people have done testing by attaching the step wedge inside the film holder, against the film. Since this is a contact print, albeit inside the camera, it is not affecte by lens flare. So this is a legitimate way to make a sensi wedge, EXCEPT for the issue of light fall-off as you get more and more off-center. So if you do it like this, you would ideally make a mathematical correction to the exposure axis. The longer the focal length of the lens, the less significant this is, so if you plan to ignore the correction, a long lens is preferable.</p>

<p>Does stouffer have a photographable step tablet?</p>

<p>Hi, I'm sure that Stouffer has reflective targets that can be directly photographed. These will be more limited in range compared to a transmission target, as well as be subject to shiny reflections (you should light them similar to copying a painting).</p>

<p>What I had suggested earlier was to actually photograph the transmission wedge that you already have. But you would need to light it from behind, such as putting it in front of a light box.</p>

<p>Either way will work, just keep in mind that lens flare will distort the darker readings, so you should take this into account.</p>