reciprocity failure adjustments: Bond 2003 factors good for 2007 400Tmax?

[Peter Collins]

Folks, I stopped down to f45 for depth of field on a close subject on a flat-light, overcast day, and after adding exposure for the bellows extension, found myself looking at 4 minutes (when overcast) or 80 seconds when sunny.

Then I recalled that my table for reciprocity failure adjustments from Howard Bond is vintage 2003, but the 'new' 400Tmax data sheets are late 2007, and was first sold in early 2008.

So, I ask, should I use Howard's data?

Thanks for the help!!

[Peter Collins]

What???? No comments?

[Jim Noel]

Folks, I stopped down to f45 for depth of field on a close subject on a flat-light, overcast day, and after adding exposure for the bellows extension, found myself looking at 4 minutes (when overcast) or 80 seconds when sunny.

Then I recalled that my table for reciprocity failure adjustments from Howard Bond is vintage 2003, but the 'new' 400Tmax data sheets are late 2007, and was first sold in early 2008.

So, I ask, should I use Howard's data?

Thanks for the help!!

THe way you chose to expose the negative doesn't quite make sense to me for the situation -but to answer your question, although either chart should get you a reasonable exposure, i always go with the manufacturer because they have much more accurate measuring tools and techniques.

[Jerry Bodine]

Peter,
If you've not already seen Patrick Gainer's article on reciprocity corrections, in which he bases his calculations on Howard Bond's 2003 data (including TMax400), the article is here. Bond's work shows that all the films he tested plotted as straight lines on log-log paper, so that you only need one exposure correction data point to come up with an equation for any given film. Evidently, the answer is not affected by variables such as developer, agitation, dev concentration/temp, density measurements, etc., also evidenced by the lack of such variables in Kodak's film data sheet (http://www.kodak.com/global/en/profe...4043/f4043.pdf) which provides two such data points to work with. It should be fairly quick/easy/inexpensive to do some tests of your own to achieve some starting points.

[Andrew O'Neill]

My data for TMY works just fine with TMY-2.

[bill fell]

I use Howard's reciprocity chart for TMax 100 from approx the same era ('03) and have no problems with new film.

[Peter Collins]

Thanks, folks! Your insights have helped immensely.