Photographing a Transmission Target for Ralph Lambrecht's Zone System Test
I would like to try Ralph's testing procedure, described in the 2nd edition of Way Beyond Monochrome, pages 217-224. I am not sure what is the best/sensible/easy way to photograph a Stouffer transmission target for this test. I will be using my 4x5 camera, in what is likely to be a 1:1 scale, or close to it.
Ralf suggests using a slide duplicator (I don't have one), or placing the target on a light table. However he also suggests using the type of light that one normally uses for their photography. Most of my photography is landscape, so I suppose I should use daylight and not the CFL light of my light table. I guess I would need to construct a temporary light table from some milky plexi, and perhaps a reflective white sheet behind it, hoping for a cloudy day (well, in Ireland this one is pretty much guaranteed, it seems, except for today). The target would be placed on this plexi, and then I would have to shield the contraption, somehow, from any reflected light, so that it was functioning as a transmission tablet.
Is that a correct way to approach it? Could I simplify somehow? Is this what others have done, who have attempted his testing procedure? I'd be grateful for any suggestions.
Why wouldn't one photograph a reflection target? Based on what you're describing, and another current thread my view is people make this stuff too complicated and the testing conditions, theoretical values etc become too far removed from actual field conditions for the attempted level of "precision" to translate to actual photography. Things like flare get in the way. Not to mention these tests do not typically yield a full H&D curve that plots out to high densities.
Last edited by Michael R 1974; 06-19-2012 at 12:27 PM. Click to view previous post history.
So here's what I do.
- Insert the film into the 4x5 holder.
- Insert the step tablet over top.
- Turn on your light table.
- Take a meter reading off the light table.
- Add 4 stops. Set the shutter/aperture.
- Focus your camera to infinity.
- Add a filter or filter adapter ring to the lens, and ** gently ** lay the camera lens down onto the light table. (yep that's what I do.)
- Take the photograph.
I contact the film as in Nick's suggestion but I photograph a white matboard in the shade, lens set to inifinity, the film exposed to +4 or +5. I don't suggest letting sunlight strike the target.
why noy just tape it to a window?
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whoever wants to contzcr me directly, don't forget, i can also be reached on skype,under 'ralph lambrecht' or the email addreass below.
Thanks for suggesting this, Ralph, and for responding to my question, I appreciate it.
Originally Posted by RalphLambrecht
Wouldn't it be necessary to eliminate the reflections from the surface of the tablet when taped to a window (or to a milky plexi)? Similar to Michael's question, I am not quite sure why the procedure suggests the use of a transmission target, as opposed to a reflection one. I suspect it is easier to make transmission work accurately than dealing with different types of reflections, but I would love to know your thinking about this a little more. In any case, taping a tablet to a window would still leave an element of reflected light in play, unless the tablet-to-lens path was somehow shielded. I realise that those reflections would be a good few stops less than the transmissions, but wouldn't they matter?
I think I understand why it is necessary to have the entire optical system in use, lens, bellows etc, so as to account for the flare, shutter behaviour, aperture etc, while performing the test. I wonder if having the tablet sandwiched to the film, as Nick and Chuck mentioned, would make a significant difference to the results.
Ralph, you are very generous suggesting that I contact you by email or Skype. If you don't mind, I would like to take you up on this offer, especially when I have run the tests, perhaps in the next two weeks. I am about to order a densitometer today—I've never had one in the years I've been printing... Time to get that experience under my belt. "Way Beyond Monochrome" is an amazing compendium of knowledge, supported by logic, and it has awoken my desire to rethink and to question many of my habits. There is nothing else approaching the scope and the detail of your and Chris's book on the market, nowadays.
Rafal - a note of caution if I may.
A densitometer is a useful tool, but make sure you don't become overly reliant on it when you test your materials. It should go hand in hand with actual printing tests. It is easy to get caught up in densitometer results, only to find in actual photography you're not getting what you wanted - or what you thought you wanted. I've seen this happen to people when they acquire a densitometer and start systematically determining their films speeds, development times for N, N-, N+ etc all based on theory and generally accepted target ranges (example - find a development time that gives a zone VIII net density of 1.2). Then they start making actual negatives and printing them, and find they are not getting the results they expected or wanted.
Don't misunderstand me - I own a densitometer and I'm glad I have it. But, make sure you combine densitometry testing with "field" testing. Test your densitometry results by applying them to photographs, and make prints. Target density values can be good guidelines, but they are far from absolute. One person's N might be another person's N-1, etc.
Thank you, Michael, for the wise advice. I approach the testing, and the purchase of a densitometer, with a purpose. I've been printing for over 30 years, but with a more serious regularity, and in LF, only for just over 10. Over this last period, I noticed that I would like to get more shadow detail than I was getting, in high contrast scenarios, and that I would like to have more control over the appearance of highlights without having to traverse paper grades from 2 to 4.
I am also on a quest to wean myself off split-grade printing, which has worked well for me—I have managed to get 24 pieces into a successful exhibition thanks to that technique—but which is now a crutch I want to let go, so as to simplify my dodging and burning, partly a function of the benefits but also complexity of Ilford 500H head. I have also missed the metronome for far too long...
Though I usually print at 2.5, I have, I think, too many grade 3, 3.5, 1.5, and an odd few even grade 4 prints. Mind it, the subjects I photograph, and the way I want them printed, tend to have their contrast ranges a bit all over the place, and I am still learning how to control it. All these years I have been using box speeds and the Massive Dev Chart timings, plus 40% for N+1, and perhaps -30% for N-1. Last year, after I attended John Sexton's wonderful workshop, I have started to cut the speed of films I used. The dev times had to be cut too, but now there was less data as to how to do it—Dev Chart provides too many answers for these cases. Still, this has made my negatives much easier to print!
What I would like to do now, is to formalise the times and speeds, hence the adventure into densitometerland. I hope this gives some context to my question. Besides, all of you guys seem to have enjoyed that adventure... Off to run some evenness of development tests now...
A reflection target can only send a limited range of illumination back to the camera - something like 3% to 95% reflection. A transmission scale can send a much wider range of light because you are shooting the light through logarithmically small dark patches that can be a hundredth of a percent or less. With reflection, you get a few percent of the bright light in your darkest patch.
Testing using a reflection target is possible, but you tackle the problem with a different approach. You take several shots per test series shooting something like a gray card, altering the amount of light hitting the film - one step at a time - by varying the shutter speed and f/stop. It's a lot more work for full film curve testing, but good for speed point tests.
Sekonic makes a reflection target design with an 18% gray patch closely surrounding with patches reflecting plus and minus 1/6, 2/6, 3/6 stop. You might be able to find speed point faster with this target than you would with a standard gray card.